revista portuguesa de ciências do desporto

Transcription

Auxological and Epidemiological Aspects of Young Athletes
Psycho-Social Aspects in Pediatric Exercise Science
Clinical/Medical Aspects in Pediatric Exercise Science
Physiological and Endocrinological Aspects in Pediatric Exercise Science
Physical Activity, School Environment and Motor Performance
Publicação semestral — Vol. 3, Nº 2 — Setembro 2003, Suplemento — ISSN 1645–0523 — Dep. Legal 161033/01
Setembro
Vol. 3, 2003,
Nº 2 Suplemento
A RPCD tem o apoio da FCT
Programa Operacional
Ciência, Tecnologia, Inovação
do Quadro Comunitário
de Apoio III
Esta edição teve o
apoio da Fundação
Calouste Gulbenkian
revista portuguesa de
ciências do desporto
Volume 3 · Nº 2
Setembro 2003
Suplemento
revista
19.9.03
0:49
Página 1
revista
19.9.03
0:49
Página 1
Revista Portuguesa de Ciências do Desporto
Publicação semestral da Faculdade de Ciências do
Desporto e de Educação Física da Universidade do Porto
Vol. 3, Nº 2, Setembro 2003 – Suplemento, ISSN 1645-0523. Dep. Legal 161033/01
Director
Jorge O. Bento
[jbento@fcdef.up.pt]
Editor
António T. Marques
[amarques@fcdef.up.pt]
Corpo editorial
Amândio Graça [agraca@fcdef.up.pt]
Ana Maria Duarte [aduarte@fcdef.up.pt]
Eunice Lebre [elebre@fcdef.up.pt]
João Paulo Vilas-Boas [jpvb@fcdef.up.pt]
Jorge Mota [jmota@fcdef.up.pt]
José Alberto Duarte [jarduarte@fcdef.up.pt]
José Alberto Moura e Castro [mcastro@fcdef.up.pt]
José Maia [jmaia@fcdef.up.pt]
José Pedro Sarmento [psarmento@fcdef.up.pt]
Júlio Garganta [jgargant@fcdef.up.pt]
Ovídio Costa [ovidiocosta@mail.telepac.pt]
Rui Garcia [rgarcia@fcdef.up.pt]
Design gráfico e paginação
Armando Vilas Boas [avboas@fcdef.up.pt]
Capa
Armando Vilas Boas [www.avbdesign.com]
Impressão e acabamento
Multitema [www.multitema.pt]
Assinatura Anual
Portugal e Europa: 25€, Brasil e PALOP: 30€ (USD 30),
outros países: 35€ (USD 35)
Preço deste número
Portugal e Europa: 15€, Brasil e PALOP: 20€ (USD 20),
outros países: 25€ (USD 25)
Tiragem
500 exemplares
Copyright
A reprodução de artigos, gráficos ou fotografias só é permitida
com autorização escrita do Director.
Endereço para correspondência
Faculdade de Ciências do Desporto e de Educação Física
da Universidade do Porto
Rua Dr. Plácido Costa, 91 · 4200.450 Porto · Portugal
Tel: +351–225074700
Fax: +351–225500689
www.fcdef.up.pt
expediente@fcdef.up.pt
A RPCD está indexada no SPORTDiscus.
Consultores
Adroaldo Gaya (Universidade Federal Rio Grande Sul)
Alberto Amadio (Universidade São Paulo)
Alfredo Faria Júnior (Universidade Estado Rio Janeiro)
Almir Liberato Silva (Universidade do Amazonas)
Anthony Sargeant (Universidade Manchester)
Antônio Carlos Guimarães (Universidade Fed. Rio Grande Sul)
António da Paula Brito (Universidade Técnica Lisboa)
António Prista (Universidade Pedagógica Moçambique)
Apolônio do Carmo (Universidade Federal Uberlândia)
Carlos Carvalho (Instituto Superior da Maia)
Carlos Neto (Universidade Técnica Lisboa)
Cláudio Gil Araújo (Universidade Federal Rio Janeiro)
Dartagnan P. Guedes (Universidade Estadual Londrina)
Duarte Freitas (Universidade da Madeira)
Eckhard Meinberg (Universidade Desporto Colónia)
Eduardo Archetti (Universidade de Oslo)
Eduardo Kokubun (Universidade Estadual Paulista, Rio Claro)
Francisco Camiña Fernandez (INEF Galiza)
Francisco Carreiro da Costa (Universidade Técnica Lisboa)
Francisco Martins Silva (Universidade Federal Paraíba)
Gaston Beunen (Universidade Católica Lovaina)
Glória Balagué (Universidade Chicago)
Go Tani (Universidade São Paulo)
Gustavo Pires (Universidade Técnica Lisboa)
Hans-Joachim Appell (Universidade Desporto Colónia)
Helena Santa Clara (Universidade Técnica Lisboa)
Hermínio Barreto (Universidade Técnica Lisboa)
Hugo Lovisolo (Universidade Gama Filho)
Ian Franks (Universidade de British Columbia)
Jan Cabri (Universidade Técnica de Lisboa)
Jean Francis Gréhaigne (Universidade de Besançon)
Jens Bangsbo (Universidade de Copenhaga)
João Abrantes (Universidade Técnica Lisboa)
José Borges Gouveia (Universidade de Aveiro)
José Gomes Pereira (Universidade Técnica Lisboa)
José Manuel Constantino (Universidade Lusófona)
Juarez Nascimento (Universidade Federal Santa Catarina)
Jürgen Weineck (Universidade Erlangen)
Lamartine Pereira da Costa (Universidade Gama Filho)
Luís Sardinha (Universidade Técnica Lisboa)
Manoel Costa (Universidade de Pernambuco)
Manuel Patrício (Universidade de Évora)
Markus Nahas (Universidade Federal Santa Catarina)
Margarida Matos (Universidade Técnica Lisboa)
Maria José Mosquera González (INEF Galiza)
Michael Sagiv (Instituto Wingate, Israel)
Paulo Farinatti (Universidade do Estado do Rio de Janeiro)
Paulo Machado (Universidade Minho)
Pilar Sánchez (Universidade Múrcia)
Robert Brustad (Universidade Northern Colorado)
Robert Malina (Universidade Estado Michigan)
Sidónio Serpa (Universidade Técnica Lisboa)
Valdir Barbanti (Universidade São Paulo)
Víctor Matsudo (CELAFISCS)
Víctor da Fonseca (Universidade Técnica Lisboa)
Víctor Lopes (Instituto Politécnico Bragança)
Wojtek Chodzko-Zajko (Universidade Illinois Urbana-Champaign)
revista
19.9.03
0:49
Página 2
Revista Portuguesa de
Ciências do Desporto
11
Invited Speakers
Vol. 3, Nº 2, Setembro 2003 – Suplemento
ISSN 1645-0523
Dep. Legal 161033/01
31
AUXOLOGICAL AND EPIDEMIOLOGICAL
ASPECTS OF YOUNG ATHLETES
45
PSYCHO-SOCIAL ASPECTS
IN PEDIATRIC EXERCISE SCIENCE
51
CLINICAL/MEDICAL ASPECTS
73
PHYSIOLOGICAL AND ENDOCRINOLOGICAL
ASPECTS IN PEDIATRIC EXERCISE SCIENCE
121
PHYSICAL ACTIVITY, SCHOOL ENVIRONMENT
AND MOTOR PERFORMANCE
173
Author Index
Programa Operacional Ciência,
Tecnologia, Inovação do Quadro
Comunitário de Apoio III.
apoio da Fundação
Calouste
Gulbenkian
revista
19.9.03
0:49
Página 3
Saudação
Jorge Bento
O presente número da RPCD tem um carácter especial, por se assumir como uma espécie de livro de
actas do 22nd PEDIATRIC WORK PHYSIOLOGY MEETING, realizado na FCDEF-UP entre 15 e 18 de
Setembro do corrente ano. Mais ainda, a particularidade deste número decorre também do facto dos trabalhos publicados estarem escritos em inglês. Este
último aspecto poderá porventura provocar num leitor mais propenso a reacções ligeiras uma sensação
de contradição ou paradoxo. Mas não é caso para
isso, por várias e profundas razões.
Esta revista, ao dizer-se portuguesa, referencia um
idioma e por via dele o espaço em que o português
serve de instrumento de comunicação. Ou seja, mais
do que afirmar a língua portuguesa, a revista pretende congregar, estimular, promover e divulgar a comunidade académica, científica e sócio-profissional que
pensa, reflecte e fundamenta em português os problemas do desporto em sentido lato. Ela é pois movida
por um espírito de inclusão e abertura e não de exclusão e clausura. Não se confina às grandezas da nação
ou região; o seu horizonte é o da internacionalização.
A RPCD limitaria gravemente as possibilidades de
cumprimento da sua missão, se virasse as costas e
cerrasse as portas aos especialistas eminentes que se
expressam noutros idiomas. Se assim procedesse,
trairia o seu desígnio que é precisamente o de colocar a comunidade lusófona em sintonia e em diálogo
com o pensamento e o conhecimento mais avançados na nossa área científica e profissional no panorama internacional. É nesse cenário global que nos
queremos situar com um sentimento de pertença
cada vez mais reforçado. O nosso auto-conceito e a
nossa auto-estima não se forjam no isolamento, que
é sempre fonte de apoucamento e de ignorância;
pelo contrário, as suas raízes e motivos vinculam-se
ao desejo de ter voz e assento no coro polifónico
universal.
Há alguns séculos atrás os portugueses estiveram na
linha da frente na aventura da mundialização, da
miscegenação e da tentativa de criação de um
mundo pautado pela conjugação harmoniosa da unidade e da diversidade. Hoje, mais do que noutros
tempos, importa seguir por essa rota e navegar em
direcção a esse destino por todos os mares da razão,
do afecto e do entendimento. É por isso que saudamos vivamente os participantes no 22nd PEDIATRIC
WORK PHYSIOLOGY MEETING e os autores dos textos que figuram neste número da RPCD. Sejam
todos bem-vindos ao Porto e a esta revista. Voltem
sempre, para seu e nosso bem!
revista
19.9.03
0:49
Página 4
revista
19.9.03
0:49
Página 5
22nd
Pediatric Work
Physiology Meeting
Porto, Portugal
September 15–18, 2003
Portuguese Journal of Sport Sciences
Volume 3, Number 2
September 2003, Supplement
revista
19.9.03
0:49
Página 6
revista
19.9.03
0:49
Página 7
CONGRESS PRESIDENT
José Maia
Dear friends and colleagues,
INTERNATIONAL SCIENTIFIC COMMITTEE
Han Kemper (Europe)
Risto Telama (Europe)
Gaston Beunen (Europe)
Robert Malina (USA)
Lars Bo Anderson (Europe)
Jorge Mota (Europe)
Alvaro Aguiar (Europe)
José Alberto Duarte (Europe)
Thomas Rowland (USA)
Stuart Bidlle (Europe)
Ilse De Bourdeaudhuij (Europe)
Oded Bar-Or (Canada)
Cameron Blimkie (Canada)
It is a great honour to our Faculty of Sport Sciences
and Physical Education to host the 22nd Pediatric
Work Physiology meeting.
Our Faculty is a young one, and hosting this congress with some of the most renowned scientists in
the field will surely leave its marks of some accomplishment of our part. Of course the knowledge of
the state of art in many areas that all of you will
share shall be seminal in the development of news
ideas and insights towards the future.
We are indebt towards all of you for the trust in our
capacity and readiness for the organization of such
an event in such a short time.
Please feel yourselves at home, profit as much as
you can from this extraordinary meeting and enjoy
Porto, a cultural heritage of mankind.
LOCAL SCIENTIFIC COMMITTEE
Jorge Olímpio Bento
António Teixeira Marques
Jorge Mota
António Manuel Fonseca
José Manuel Soares
João Paulo Vilas-Boas
Carla Rego
José Maia
revista
19.9.03
0:49
Página 8
revista
19.9.03
0:49
Página 9
INVITED SPEAKERS
revista
19.9.03
0:49
Página 10
revista
19.9.03
0:49
Página 11
Invited speakers
PHYSICAL GROWTH, MATURATION AND PERFORMANCE:
BACK TO THE FUTURE
Beunen Gaston
Department of Sport and Movement Sciences, Faculty of Physical
Education and Physiotherapy, K.U.Leuven, Leuven, Belgium
In order to advance our knowledge in auxology, as it relates to
performance and physical activity, we need to look back on
what is presently already documented and which scientific procedures have been used to accumulate this knowledge.
Undoubtedly my account will be biased by my knowledge and
interests in this area and it is certainly not be regarded as an
historical meta-analysis of the field.
My walk through the gardens of our field from an auxological
perspective will cover the following topics :
— the design of growth studies and questions that can be
answered
— growth patterns and impact of physical activity
— stages of motor development: towards a theory of motor
development
— pediatric biomechanics a field of study
— norms for physical fitness and activity
The design of growth studies
Over the last century our predecessors have used four research
designs to answer auxiological questions i.e. (1) cross sectional
designs to provide reference data on the present states of
growth and maturation of representative samples, (2) longitudinal designs to investigate growth patterns, growth velocity,
and tracking, (3) time-lag designs to document secular changes
over time, and (4) most recently multiple or mixed longitudinal studies. These mixed longitudinal studies were first proposed by Schaie (1965) a developmental psychologist, as the
most efficient design to study developmental changes. The
design permits, under certain assumptions, to differentiate
between growth, cohort and time of measurement effects.
Although I believe that the design is indeed appropriate to
answer a number of questions, it is not adequate for a number
of questions that are still of major interest for future research.
Our knowledge is indeed very limited with regard to the adolescent changes in a variety of performance characteristics in
boys and especially in girls (Malina & Bouchard 1991, Beunen
& Malina 1996). We barely know if there is a growth spurt in
a number of fundamental fitness abilities or physiological functions. Furthermore there is a complete lack of knowledge
about adolescent changes in a variety of motor skills, and longitudinal studies, covering long enough periods, of elite athletes are also lacking (Malina 1994). Finally there is also a
large gap in our knowledge about the mechanisms (metabolic),
biochemic, physiologic, molecular, biomechanic, endocrinologic) that underly patterns in somatic growth, maturation and
performance characteristics.
Growth patterns and impact of physical activity
Frank Shuttleworth (1937) was the first to recognize that in
order to identify correctly changes in the growth or maturation
process, individual growth data have to be synchronized on
biological milestones. This has been successfully applied to
somatic dimensions in a number of European and North
American longitudinal studies (Tanner 1981, Malina &
Bouchard 1991), and to a limited number of performance characteristics (Beunen & Malina 1988). This also has led to the
development of a number of mathematical functions to adequately describe the growth process. We now have an accurate
description of the growth velocity in postnatal stature and the
characterization of the adolescent growth spurt has been carefully documented (Tanner, Whitehouse & Takaishi 1966).
Recently it has been demonstrated that over short periods of
time, growth in length is characterized by a salutatory growth
pattern (Laugh et al. 1992), or by repeated small continuous
growth accelerations or little growth spurts (Hermanussen et
al. 1988). Regardless of the fact that this process of short term
growth is salutatory or continuous with small sports, the question remains unanswered if this occurs in different body parts,
tissues and/or performance characteristics, and why these
changes in velocity occur. Furthermore, there is a need for
short term experimental growth studies to document the
impact of physical activity on the short term growth process.
Stages of motor development
In the first decades of last century Gesell (1928) and his collaborates contributed greatly to our knowledge with the detailed
description of stages in motor development early in life in a
variety of fundamental motor behaviors.
Furthermore the stages of motor development in a number of
gross motor behaviors of the pre-school child have been accurately described (Gallahue & Ozmun 2002, Keogh & Sugden 1985).
Unfortunately, these descriptions are qualitative and no underlying mechanisms are identified. A notable exception is the
work of Thelen (1991) and her collaborators. They made a significant effort to apply the theory of dynamic systems to
explain infant behavior in motor tasks such as learning to walk.
This theory is probably a good starting point to go beyond the
purely descriptive stage of motor development. Here the input
of recent advances in the neurosciences, motor control and
techniques such as magnetic resonance imaging of brain functions need to be integrated (Knutzen & Martin 2002).
Pediatric biomechanics
In a recent review it was clearly demonstrated that our knowledge about biomechanical parameters of movement behavior,
skills and performance characteristics of children and adolescents is fragmented (Knutzen & Martin 2002).
Tremendous efforts and advances have been made in the biomechanical analysis of a variety of sport skills, and biomechanics have also contributed significantly to the development of
better ortheses, protheses, surgical interventions and safe and
efficient training and rehabilitation programs. Even in the field
of gerontology biomechanists have joined the geriatric teams.
The largely forgotten species are the children and adolescents.
As already indicated in the previous section, we have to go
beyond the descriptive stage in motor development and pediatric biomechanics can help to further our understanding and
to develop theories about motor development throughout the
whole growth process.
Norms for physical fitness and physical activity
Since Sargent proposed the vertical jump as a test of a man
(1921), the concept of physical fitness, its components and the
tests used to quantify these components has evolved considerably (Bouchard & Shephard 1994). In the eighties there has
been a shift towards health- and performance-related fitness.
Revista Portuguesa de Ciências do Desporto, 2003, vol. 3, nº 2 [11–28]
11
revista
19.9.03
0:49
Página 12
Invited speakers
And along the same lines, attempts have been made to define
criterion-referenced norms. Unfortunately, the criteria that
have been used mostly lack validity. Only for aerobic power
some evidence exists about the health associations and the cutoff scores that could be used in adults (Updyke 1992). For all
other so called health-related fitness items virtually no such
evidence is readily available. There is thus a need to reconsider
fitness tests, and probably to reconsider the split in health- and
performance-related fitness items. Furthermore, there is a
need to provide evidence for the associations with health, risk
factors, and construct valid cut-off scores (Updyke 1992).
Along the same lines we learned a lot about the beneficial effects
of physical activity on health and disease. In children and adolescents this is limited to a number of risk factors and the effects
are often limited or at best moderate (Riddoch 1998).
Again, here we need to study what is the optimal physical
activity (mode, frequency, intensity, time) that children and
adolescents need for their physical, mental and psycho-social
health, well-being, optimal, harmonious development, and later
health outcomes.
References
Beunen G, Malina RM (1988) Exerc Sp Sc Rev 16:503-540
Beunen G, Malina RM (1996) in Bar-Or O (ed) The child and adolescent athlete: 3-24
Bouchard C, Shephard RJ (1994) in Bouchard C et al. (eds) Physical
activity, fitness and health
Gallahue DL, Ozmun JC (2002) Understanding motor development
Gesell A (1928) Infancy and human growth
Hermanussen M, Geiger-Benoit K, Burmeister J, Sippell WG (1988)
Ann Hum Biol 15:103-109
Keogh J, Sugden D (1985) Motor skill development
Knutzen KM, Martin LA (2002) Ped Exerc Sc 14:222-247
Lampl M, Veldhuis JD, Johnson ML (1992) Science 258:801-803
Malina RM (1994) Exerc Sp Sc Rev 22 :389-433
Malina RM, Bouchard C (1991) Growth, maturation and physical activity
Riddoch C (1998) in Biddle S, Sallis J, Cavill N (eds) Young and active
Sargent DA (1921) Am Phys Educ Rev 26:188-194
Schaie KW (1965) Psychol Bull 64:92-107
Tanner JM (1981) A history of the study of human growth
Tanner JM, Whitehouse RH, Takaishi M (1966) Arch Dis Childh
41:454-471
Thelen E, Ulrich BD (1991) Mon Soc Res Child Dev 51(1)
Updyke WF (1992) Res Quart Exerc Sp 63:112-119
INCIDENCE AND PLAYER RISK FACTORS FOR INJURY IN YOUTH
FOOTBALL (AMERICAN)
Malina Robert M1, Barron Mary2, Morano Peter3,
Miller Susan J2, Cumming Sean P4, Kontos Anthony P5
1
2
3
4
5
Research Professor, Tarleton State University, Stephenville, TX
Michigan State University, East Lansing, MI
Central Connecticut State University, New Britain, CT
University of Washington, Seattle, WA
University of New Orleans, New Orleans, LA
Introduction
Risk of injury is a given in sport at all levels from youth to professional. The injury-related literature in youth sports focuses
12
largely on descriptions of risk factors related both to the host
(young athlete, internal), and to the sport environment (external), and to a lesser extent on the prevalence and incidence of
injuries. The contribution of risk factors individually or in
combination to injuries in youth sports is neither known with
certainty nor specified in available studies. Some are seemingly obvious, e.g., poor playing conditions and equipment; others
need more systematic specification. Estimates of injury rates
in studies of youth sports are limited commonly by the lack of
suitable exposure data for practices and competitions, in addition to variable definitions of injury.
Information on injuries associated with regular participation in
sport is regularly collected at the high school and collegiate levels in the United States. However, it is at the local level where
numbers of participants in youth sports are greatest. About
five times as many children and youth under the age of 14 participate in organized youth sports as participate in interscholastic sports (Carnegie Corporation, 1997); yet, relatively little is
known of the prevalence and incidence of injuries at the youth
sport level. The presently available data are variable and often
limited to accident reports; records from hospitals, emergency
rooms and sport injury clinics; interviews; and retrospective
questionnaires (Malina, 2001). These studies provide estimates of age-, sex- and sport-associated variation in the occurrence and type of injuries. The specific contexts of injuries are
generally not considered.
The purposes of the study were threefold: (1) to estimate the
incidence of injuries in youth football (American), (2) to assess
the perception of the risk of injury in football by the participants, and (3) to assess the relationship between player-related
risk factors (body size, biological maturity status, perception of
risk of injury) and the occurrence of injury in youth football.
Injuries in American Football among Youth
In an early study, the type and frequency of injuries occurring
during a 12 week season in about 2000 participants in tackle
football 9-15 years were described (Roser and Clawson, 1970).
Coaches reported injuries; the criterion was “…missing practice or a game.” Only 48 injuries were reported (2.3% of the
players); they were more likely to occur in games rather than in
practice. In a more recent study of about 5000 players 8-15
years (Goldberg et al., 1988) a similar protocol was used, i.e.,
coaches reported injuries, but reported injuries were those that
“…required restricted participation for more than 1 week.”
During the season (August to November), 257 injuries were
reported (about 5%). Injuries occurred more often in heavier
players, in participants who had more playing time, and in
quarterbacks and running backs. Age and height were not considered in the analysis. Data for injuries in high school football are more extensive, and estimated rates are higher than for
youth football (Thompson et al., 1987). However, studies vary
in definitions of injury and methods of reporting. A 5 year epidemiologic study involving about 9000 high school football
players in North Carolina considered an injury when it restricted “usual activity for one day beyond the day of the injury,” or
when it required professional treatment (Blyth and Mueller,
1974). With these criteria, the estimated injury rate was lower
than corresponding data based on insurance claims. Rates
increased with age, weight and height, but interrelationships
among these variables were not considered. The distribution of
injuries was approximately equal between games and practices.
In one of the more complete analyses of injuries in several high
revista
19.9.03
0:49
Página 13
Invited speakers
school sports, reportable injuries were more systematically
defined relative cessation of and return participation on the day
of injury or the following day, and fractures, dental injuries,
and mild brain injury (Powell and Barber-Foss, 1999). The
overall case rate for high school football was 8.1/1000 athlete
exposures (AE), but rates were higher for games versus practice, 26.4/1000 and 5.3/1000 AE, respectively.
Variation in maturity status, size and physique are often indicated as risk factors for injury in American football. Skeletal
age did not differ between injured and non-injured junior high
school players 13-16 years of age (Rochelle et al., 1961), and a
composite index of sexual maturity differed only slightly
between injured and non-injured high school players 13-17
years of age (Violette, 1976). Body build and “looseness” of
joints were poor predictors of injury in high school football
players (Godshall, 1975), but an elevated BMI was associated
with greater risk for lower extremity injuries among high
school linemen (Gomez et al., 1998).
Systematic data on the incidence of injuries in American football for youth at the community level, i.e., below the interscholastic level, are limited. Although the available data suggest lower rates than for high school football, suitable exposure
statistics are not reported and variable definitions of an injury
are used. Host- or player-related risk factors are not systematically considered.
Methods
Subjects were 678 boys, 9-14 years of age, who were members
of 33 youth football teams in two central Michigan communities in the 2000 and 2001 seasons (Mid-Michigan PONY
League). Teams were formed by players’ grade in school. Each
community had combined 4th-5th, and 6th and 7th grade teams;
one community had 8th grade teams.
Height and weight were measured at the start of the season;
the BMI (wt/ht2) was calculated. The RISK OF INJURY IN
SPORTS SCALE (RISSc) was completed. The scale included 24
items reflecting six risk factors: uncontrollable, controllable,
overuse, upper body, surface-related, and re-injury (Kontos et
al., no date). Parents reported their heights, which were
adjusted for overestimation (Epstein et al., 1995). Age, height
and weight of the player and midparent height were used to
predict the adult height for the boy (Khamis and Roche, 1994).
The player’s current height was expressed as a percentage of
predicted adult height to provide an estimate of biological
maturity status (Roche et al., 1983; Malina et al., 2003).
Three graduate assistants, who were certified athletic trainers,
measured the players and administered the risk scale. The
trainers were on site to record the number of participants at all
practices and games, i.e., coach-directed sessions which were
opportunities for injury (exposures) and injuries as they
occurred. A reportable injury was defined after Powell and
Barber-Foss (1999, p. 278): “Any injury that causes cessation of
participation in the current game or practice and prevents the
player’s return to that session, … that causes cessation of a
player’s customary participation on the day following the day
of onset.” All fractures, dental injuries, and any mild brain
injury were also classified as reportable injuries. The trainers
also provided on field care for injuries. Information about the
type, location (body part) and severity of injuries, position or
activity of the injured player, and context were recorded.
Case rates based on athlete exposures (AE), total number of
injuries per 1000 AE, were calculated by grade and for the total
sample. Case rates were calculated for practices and games, and
both combined. Hierarchical log linear modeling was used to
identify variables that were potentially related to injury status.
Logistic regression was used to evaluate the relationship
between player-related risk factors (body size, estimated maturity status, perception of risk) and the risk of injury.
Results
Mean heights of the sample move from the U.S. reference
median at 9 years towards the 75th percentile at 14 years.
Mean weights move from the 75th percentile of the reference at
9 years to just below the 90th percentile at 14 years. As a
result, the BMI, on average, is slightly below the 85th percentile
of the reference from 10 to 14 years of age. Many of the players
would be classified as overweight and/or obese.
Over the two seasons and across grades, there were 24,854
exposures, 20,496 in practices (82.5%) and 4,358 (17.5%) in
games. The injury rate was 10.4/1000 AE, but the rate was
twice as high in games (18.6/1000AE) as in practices
(8.7/1000 AE). Case rates per AE during practices increased
with grade level, whereas corresponding case rates during
games were about twice as great in the 7th and 8th grades compared to the lower grades (Table 1). Case rates for games
among 7th and 8th grade players (26.1 and 27.4/1000 AE) were
virtually identical to estimates for high school players
(26.4/1000 AE) using the same definition of a reportable
injury (Powell and Barber-Foss, 1999). Case rates for pratices,
ever, were higher in 7th and 8th grade players (10.7 and 13.6)
than in high school players (5.1).
Table 1. Estimated injury rates (case rates per 1000 AE) within grade.
About two-thirds of the injuries was classified as minor in
severity, so that case rates per AE for injuries of moderate
(18%) and major (13%) severity were very low (Table 2).
Table 2. Estimated injury rates (case rates per 1000 AE)
by severity within grade.
The youth football players exhibited moderate levels of perceived risk. Scores on five of the six risk factors were significantly higher among 4th-5th grade players, but did not differ
between 6th and 7th-8th grade players. This suggests that the
perception of risk of injury decreases with age and perhaps
experience. The sixth, concern for re-injury, was significantly
higher among 7th-8th grade players, followed by 6th and then
13
revista
19.9.03
0:49
Página 14
Invited speakers
4th-5th grade players, suggesting that concern for re-injury
increases with age and experience in football.
Results of logistic regressions within grade indicated no consistent pattern of associations between age, indicators of body size
and maturity status and risk of injury. When scores on the
RISSc were included in the logistic regressions with age, body
size and maturity status within grade, there were no consistent
associations with risk of injury. However, when the total sample was treated as a single group, high concern for re-injury and
grade emerged as predictive of injury. This suggests that older,
presumably more experienced players who scored high on the
perception of risk related to re-injury were more at risk for
injury. And, players in 7th and 8th grades combined are more
likely to be injured than those in the 4th through 6th grades
combined. This probably reflects the fact that games in the two
older grades more closely follow high school rules (e.g., inclusion of special teams), whereas rules for kick-offs and punts are
modified for the lower grades (e.g., no run backs).
Conclusions
Injuries occurred twice as often in games as in practices. Case
rates (per 1000 AE) for games and practices were lower among
4th-5th and 6th grade players than among 7th and 8th grade players. Body size and estimated biological maturity status were
not significant risk factors for injury in youth football. Among
perception of risk factors, concern for re-injury increased with
grade and was significantly related to risk of injury.
Athletes classified as advanced, average or late in biological
maturity status on the basis of percentage of predicted adult
height showed the same pattern of variation in body size compared to studies which used more traditional and invasive estimates of maturity status (skeletal age and secondary sex characteristics). This emphasizes the potential utility of percentage of
predicted adult height as a non-invasive indicator of biological
maturity status for use in studies of injuries in youth sports.
American football is a sport in which large body size is an
advantage, and many boys are selected for a position by their
body size. By about 12-15 years, boys assigned to line positions (interior linemen and linebackers) are generally taller and
especially heavier than boys who are receivers, running backs
and quarterbacks, and it is not uncommon for position specialization to start at these ages.
Acknowledgement
This research was funded by the National Athletic Trainers’
Association Foundation, grant # 300R001.
References
Blyth CS, Mueller FO (1974) Football Injury Survey. Part I: When
and where players get hurt. Phys SportsMed 2:45-52 (Sept).
Carnegie Corporation (1997) The Role of Sports in Youth
Development. New York: Carnegie Corporation, pp 1-157.
Epstein LH, Valoski AM, Kalarchian MA, McCurley J (1995) Do children lose and maintain weight easier than adults: A comparison of
child and parent weight changes from six months to ten years. Obes
Res 3:411-417.
Godshall RW (1975) The predictability of athletic injuries: An eightyear study. J Sports Med 3:50-54.
Goldberg B, Rosenthal PP, Robertson LS, Nicholas JA (1988) Injuries
in youth football. Pediatrics 81:255-261.
Gomez JE, Ross SK, Calmbach WL, Kimmel RB, Schmidt DR,
Dhanda R (1998) Body fatness and increased injury rates in high
14
school football lineman. Clin J Sports Med 8:115-120.
Khamis HJ, Roche AF (1994) Predicting adult stature without using
skeletal age: The Khamis-Roche Method. Pediatrics 94:504-507; erratum 95:457 (1995).
Kontos AP, Feltz DL, Malina RM (no date) The development of the
Risk of Injury in Sports Scale (RISSc). Submitted for publication.
Malina RM (2001) Injuries in organized sports for children and adolescents. In Children and Injuries, JL Frost (ed). Tucson, AZ: Lawyers
and Judges Publishing Company, pp 199-248.
Malina RM, Bouchard C, Bar-Or O (2003) Growth, Maturation, and
Physical Activity, 2nd edition. Champaign, IL: Human Kinetics.
Powell JW, Barber-Foss KD (1999) Injury patterns in selected high
school sports: A review of the 1995-1997 seasons. J Athletic Train
34:277-284.
Roche AF, Tyleshevski F, Rogers E (1983) Non-invasive measurements
of physical maturity in children. Res Q Exerc Sport 54:364-371.
Rochelle RH, Kelliher MS, Thornton R (1961) Relationship of maturation age to incidence of injury in tackle football. Res Q 32:78-82.
Roser LA, Clawson DK (1970) Football injuries in the very young
athlete. Clin Orthop 69:219-223.
Thompson N, Halpern B, Curl WC, Andrews JR, Hunter SC, McLeod
WD (1987) High school football injuries: Evaluation. Am J Sports
Med 15:S97-S104.
Violette RW (1976) An epidemiologic investigation of junior high
school football injury and its relationship to certain physical and maturational characteristics of the players. Doctoral dissertation, University
of North Carolina, Chapel Hill.
THE RELATIONSHIP BETWEEN PHYSICAL FITNESS AND
CLUSTERED RISK, AND TRACKING OF CLUSTERED RISK
FROM ADOLESCENCE TO YOUNG ADULTHOOD
Bo Andersen Lars
Institute for Exercise and Sport Sciences, Norre Alle 51, DK-2200,
University of Copenhagen, Denmark. lbandersen@ifi.ku.dk
Introduction
Hard endpoints of atherosclerotic CVD is not prevalent in
young people, but as atherosclerosis develops gradually over
the years, it may be effective to prevent high levels in CVD risk
factors already in children. The rationale behind this thinking
is that risk factors track, i.e. subjects keep rank order within a
risk factor. Most CVD risk factors show moderate tracking
(1,2). A tracking coefficient is a measure of variability between
two time points. Variation in a risk factor value is caused by
assessment error, short time fluctuations, and more permanent
changes in mean risk factor levels. Only the latter is interesting
in the prediction of atherosclerotic development. Many of the
risk factors show great variability caused by assessment problems and day-to-day variation, i.e. blood pressure and cholesterol show great short-term fluctuations and physical activity is
usually self reported with great assessment problems. A more
correct tracking coefficient can be obtained by minimising
some of the short-term variation, which can be removed by
repeated measurements, i.e. two to three blood samples over a
week both at baseline and at the follow-up. However, this is
rarely done in epidemiological studies. Also, assessment error
can often be diminished, but it may be expensive in large longitudinal studies. Therefore, it may be more convenient to
revista
19.9.03
0:49
Página 15
Invited speakers
analyse the stability of clustered risk. Many of the risk factors
are related to a common causal factor, the metabolic syndrome.
In an insulin insensitive person, the risk factors related to the
metabolic syndrome will be elevated simultaneously, and this
may to some extend overrule the error variation. We have earlier shown that physical fitness is weakly related to each single
CVD risk factor in cross sectional studies (3), but probably due
to a strong effect of training on insulin sensitivity, a strong
relationship is found between fitness and clustered risk (4).
The main aim of the present study was to calculate tracking of
clustered risk in an eight years longitudinal study from adolescence to young adulthood.
Methods
Two examinations were conducted 8 years apart. First time, 133
males and 172 females were 16-19 years of age. Eight years
later 98 males and 137 females participated. They were each
time ranked into quartiles by sex in four CVD risk factors all
related to the metabolic syndrome. Risk factors were the ratio
between total cholesterol and HDL, triglyceride, systolic BP and
body fat. The upper quartile was defined as being at risk, and if
a subject had two or more risk factors, he/she was defined as a
case (15-20 % of the subjects). Odds ratio (OR) for being a case
at the first examination was calculated between quartiles of fitness, and the same analysis was performed at the second examination. The stability of combined risk factors was calculated as
the OR between cases and non-cases at the first examination to
be a case at the second examination.
Results
Tracking coefficients in single risk factors were between 0.2 and
0.8. At the first examination, OR for having 2 or more risk factors between quartiles of fitness were 3.1, 3.8 and 4.9 for quartiles two to four, respectively. At the second examination, OR
were 0.7, 3.5 and 4.9, respectively. The probability for “a case”
at the first examination to be “a case” at the second was 6.0.
Conclusions
The relationship between an exposure like physical fitness and
CVD risk factors is much stronger when clustering of risk factors are analysed compared to the relationship to single risk
factors. Also, the stability over time in multiple risk factors
analysed together is strong with an OR of 6 for having 2 or
more risk factors 8 years after in those who were at risk at the
first examination. This relationship should be seen in the light
of moderate or weak tracking of single risk factors, and is a
strong evidence for a benefit of early intervention in children
where risk factors cluster.
References
1. Twisk JWR, Kemper HCG, Mechelen Wv, Post GB. (1997).
Tracking of risk factors for coronary heart disease over a 14-year period: a comparison between lifestyle and biologic risk factors with data
from the Amsterdam Growth and Health Study. Am J Epidemiol 145:
888-898
2. Andersen LB, Haraldsdóttir J (1993). Tracking of cardiovascular
disease risk factors including maximal oxygen uptake and physical
activity from late teenage to adulthood. An 8-year follow-up study. J
Int Med 234: 309-315
3. Andersen LB, Henckel P, Saltin B (1989). Risk factors for cardiovascular disease in 16-19-year-old teenagers. J Int Med 225: 157-163
4. Wedderkopp N. (2000). Cardiovascular risk factors in Danish chil-
dren and adolescents. A community based approach with a special reference to physical fitness and obesity. Institute of Sport Science and
Clinical Biomechanics, University og Southern Denmark
SOCIAL PSYCHOLOGY OF PHYSICAL ACTIVITY AND SEDENTARY
BEHAVIOUR IN YOUNG PEOPLE
Biddle Stuart
British Heart Foundation National Centre for Physical Activity & Health;
School of Sport & Exercise Sciences, Loughborough University, UK
There is growing concern over the effects of sedentary lifestyles
on the health of young people. Recent rapid increases in juvenile obesity have received a great deal of attention in the scientific and popular press and have been attributed partly to television viewing, computer games and other sedentary behaviours. These are thought to compete with physical activity.
Project STIL (Sedentary Teenagers and Inactive Lifestyles) at
Loughborough University is investigating ‘what young people
do’ and focuses on active and inactive pursuits chosen in their
leisure time. We address the following issues in young people:
a) what is the current social and psychological climate of physical activity and inactivity for young people in western society?
b) Do key sedentary media-based behaviours displace physical
activity? c) Are key media-based sedentary behaviours obesogenic? d) What are the secular trends for children and youth
for TV viewing? Our results for young people suggest that: a)
TV viewing and video-game playing are largely uncorrelated
with physical activity, suggesting that there is time for both; b)
meta-analytic findings show that body fatness is not related in
any clinically meaningful way with screen media use; c)
although more children and youth have greater access to TVs
than in previous generations, the amount of TV watched per
head has not changed for 40 years. Inactivity is more complex
than we sometimes think. Indeed, measures of ‘couch potatoism’ expressed as media use, may be inappropriate as markers
of inactivity. There is growing concern over the effects of
sedentary lifestyles on the health of young people in western
society. Recent rapid increases in obesity for this age group, as
well as for adults, have received a great deal of attention in the
scientific and popular press. Such trends have partly been
attributed to television viewing, computer games and other
sedentary behaviours thought to be occupying large amounts of
time for young people. These are thought to compete with
physical activity, thus creating an ‘inactive lifestyle’. Indeed,
there is somewhat of a ‘moral panic’ concerning the ‘couch
kids’ culture in modern western society, fuelled by adults –
themselves largely sedentary and overweight of course! –
extolling the evils of couch potato-ism!
At Loughborough University we have established Project STIL (Sedentary Teenagers and Inactive Lifestyles) to investigate ‘what
young people do’. The project1 focuses on active and inactive
pursuits chosen by young people in their leisure time. Through
this research, we hope to better understand the multifaceted correlates and determinants of such lifestyle choices and in particular the nature, extent and correlates of sedentary behaviours.
In this short paper, I will outline some key findings from our
review of the literature. Although we have data from prior
research (Marshall, Biddle, Murdey, Gorely, & Cameron, 2003;
15
revista
19.9.03
0:49
Página 16
Invited speakers
Marshall, Biddle, Sallis, McKenzie, & Conway, 2002), currently
we are collecting large-scale prevalence and smaller-scale longitudinal data, and these are not yet analysed. As part of the initial phase of the project, we have undertaken systematic
reviews of the literature. I will draw on these to answer the following questions:
Do key sedentary media-based behaviours displace physical
activity?
Are key media-based sedentary behaviours obesogenic?
What are the secular trends for children and youth for TV
viewing?
1.Do key sedentary media-based behaviours displace
physical activity?
It is commonly thought that media-based sedentary behaviours, such as TV viewing, video game playing and leisure-time
computer use, compete for time that would otherwise be spent
in physical activity. In other words, one would assume a negative correlation.
We conducted a meta-analysis of 24 studies and 41 independent samples (k) (Biddle, Marshall, Gorely, Cameron, & Murdey,
2003). Effect sizes were calculated for physical activity and TV
viewing (k = 39) and physical activity and video/computer
game use (k = 10). A total of 143,235 young people were
studied. The sample-weighted effect size (Pearson r) between
TV viewing and physical activity was -0.096 (95% CI = -0.080
to -0.112). The sample-weighted fully corrected effect size2
was -0.129. This small correlation was statistically significant
and may provide evidence for a displacement hypothesis – that
is, TV viewing displaces physical activity. However, the effect
is too small to be of much clinical or practical significance.
The sample-weighted effect size between video/computer game
use and physical activity was -0.104 (95% CI = -0.080 to 0.128). The sample-weighted fully corrected effect size was
0.141. This suggests that the relationship is best described as
‘small.’ However, this should be interpreted with caution
because the mean effect size is based on only 10 primary
effects and second-order sampling error may be present.
In summary, it appears that the displacement hypothesis has
limited support and that key media-based sedentary behaviours in young people are not strongly associated with the
amount of physical activity they undertake. This was supported by our own primary data (Marshall et al., 2003; Marshall et
al., 2002). Thus we conclude that there appears to be time for
both these behaviours.
2. Are key media-based sedentary behaviours obesogenic?
In another meta-analysis (Biddle et al., 2003), we located 30
studies with data available on 52 independent samples investigating associations between body fatness and TV viewing
and video/computer use. A total of 44,707 young people
were studied.
The sample-weighted effect size (Pearson r) between TV viewing and body fatness was 0.066 (95% CI = 0.056 to 0.078).
The sample-weighted fully corrected effect size was 0.084.
Thus, the TV viewing habits of young people explain less the
1% of the variance in their body fatness. While this relationship is statistically significant (p<.05), it is likely to be clinically irrelevant. This conclusion is in contrast to many statements in the literature.
The sample-weighted effect size between video/computer game
use and body fatness was 0.070 (95% CI = -0.048 to 0.188).
16
The sample-weighted fully corrected effect size was 0.128. The
95% CI for the sample-weighted effect size suggests that the
relationship in the population is probably zero. However, this
should be interpreted with caution because the mean effect
size is based on only 6 effect sizes.
3. What are the secular trends for children and youth for
TV viewing?
We have located 81 useable studies reporting some level of
incidence, prevalence or developmental data for the sedentary
behaviours of television viewing, video game playing or computer use in youth. From these, data were available on 463
independent samples.
Based on 45 independent samples published since 1997, the
incidence of TV viewing amongst young people is estimated to
be just under 2.5 hours per day. The mean incidence reported
for video game playing is just over 30 minutes.day-1 and for
computer use is about 45 minutes.day-1.
In accordance with the guidelines from the American Academy
of Pediatrics (1986), the boundaries for prevalence estimates
for TV viewing were set at less than 2 hours per day for ‘low
users’ and more than 4 hours per day for ‘high users’. Just
over one quarter of young people (27.67%, SD = 9.11, range 9
– 56%, K = 169) are high users of TV, but around two-thirds
(66.21%, SD = 13.93, range 35.30 – 94, K=13) appear to be
low users. A significant difference between prevalence estimates for males and females was observed, with a higher proportion of males compared to females (30% vs. 25.27%) being
high users of TV (p>.05).
We have been able to estimate secular changes in TV incidence
levels since the introduction of TV. Surprisingly, while the content of media has changed, the absolute volume appears
remarkably stable at around 35-40 hr.wk-1 for 11-17 yr olds.
This might suggest a maximum time that young people can
devote to it. However, these estimates are for the amount of
time young people watch TV and may only account for those
having TVs available. With the increasing use number of TV
sets in houses, including being located in the bedrooms of
teenagers, these estimates may be biased downwards. However,
it has yet to be established that, if it was the case that more
children are watching TV than in previous generations, whether
TV viewing is replacing previously active pursuits.
Conclusion
Inactivity is more complex than we sometimes think. Indeed,
measures of ‘couch potato-ism’, expressed as media use, may
be inappropriate as markers of inactivity in youth. There are
likely to be complex social psychological processes at work that
preclude, at this time, simple conclusions regarding whether
key sedentary behaviours such as TV viewing a) displace physically active pursuits or b) create negative health outcomes such
as overweight and obesity. One might predict that in the
absence of simple associations between these constructs, there
might be clusters, or groups, of young people showing ‘negative’ health profiles, such as high TV viewing, low physical
activity, and high body fat. It might be argued that it is these
types of young people that we need to focus on rather than on
assuming general associations between variables for all children and youth.
Acknowledgement
I acknowledge the contributions to this work of colleagues Dr
revista
19.9.03
0:49
Página 17
Invited speakers
Simon Marshall (now at San Diego State University), Dr Trish
Gorely, Professor Noel Cameron, and Ian Murdey.
References
American Academy of Pediatrics. (1986). Television and the family.
Elk Grove Village III: American Academy of Pediatrics.
Biddle, S. J. H., Marshall, S. J., Gorely, P. J., Cameron, N., & Murdey,
I. (2003). Sedentary behaviors, body fatness and physical activity in
youth: A meta-analysis [abstract]. Medicine and Science in Sport and
Exercise, 35(5, Suppl.), S178.
Marshall, S. J., Biddle, S. J. H., Murdey, I., Gorely, T., & Cameron, N.
(2003). But what are you doing now? Ecological momentary assessment of sedentary behavior among youth [abstract]. Medicine and
Science in Sport and Exercise, 35(5, Suppl.), S180.
Marshall, S. J., Biddle, S. J. H., Sallis, J. F., McKenzie, T. L., &
Conway, T. L. (2002). Clustering of sedentary behaviours and physical
activity among youth: A cross-national study. Pediatric Exercise
Science, 14, 401-417.
1 Funded by the British Heart Foundation, Health Education
Board for Scotland, and Masterfoods.
2 Corrected for sampling and measurement error.
APPLYING THE TRANSTHEORETICAL MODEL FOR CHANGE
IN PHYSICAL ACTIVITY IN YOUNG PEOPLE
De Bourdeaudhuij Ilse
Ghent University, Faculty of Medicine and Health Sciences,
Department of Movement and Sport sciences, Belgium
Research on behavioural determinants of physical activity in
youth originating from a public health perspective is relatively
new. In the past, such physical activity research focused primarily on adults, based on the assumption that adults were the
population especially at risk of ill health from physical inactivity. Children and adolescents were considered to be exercising
enough. However, recently more attention has been given to
the importance of studying physical activity in children and
adolescents, including determinants. The main reasons for this
recent focus are the increase in childhood obesity, the findings
that not all children are active enough, and the steep decline in
physical activity found in adolescence.
A good understanding of the determinants of physical activity
in youth is essential in developing appropriate activity promotion interventions resulting in long-term increases in physical
activity levels in this population. It should be noted, however,
that because of the cross-sectional nature of most studies, the
term ‘determinant’ mostly indicates only a reliable association
or correlation, and the methods used in most studies do not
allow any inference of causality.
The Theories of Reasoned Action and Planned Behaviour were
found to be relevant frameworks for studying determinants of
physical activity in youth. Perceived behavioural control and
attitudes towards physical activity have been found to be correlates of physical activity in youth. However, most studies have
shown associations between these constructs and intentions to
be physically active rather than physical activity itself. Further,
the Social Cognitive Theory, and especially its most studied
concept of self-efficacy, was found to be a strong correlate of
physical activity in children and adolescents. General, as well
as more specific measures of perceived competence in relation
to physical activity are also relevant. Empirical support has
been found for the relationship between self-efficacy and physical activity in youth.
The Transtheoretical Model, initially constructed by Prochaska
and DiClemente (1983) to explain changes made by people
who stop smoking, has also been proposed as useful for understanding the adoption and maintenance of exercise behaviour.
In the Transtheoretical Model it is argued that people progress
through the stages of change during the process of changing
their behaviour. The stages have been labelled precontemplation, contemplation, preparation, action, and maintenance. In
the precontemplation stage, individuals do not intend to
change their behaviour. In the contemplation stage, people
seriously intend to change in the next 6 months. In the preparation stage, individuals intend to take action in the near future
(within a few weeks) or are already changing their behaviour at
an inconsistent level. Action is the stage in which behaviour
changes have occurred recently (within the past 6 months). In
the maintenance stage, people have made changes more than 6
months previously or until the risk no longer exists of relapse
to the old behaviour. The result of the progression through the
stages is the stable adoption of new healthy behaviour. The
Transtheoretical Model is more a model giving guidelines for
intervention than it is a model for studying behavioural determinants per se. A major contribution of the Transtheoretical
Model, however, is its matching of determinants of health
behaviour with the readiness of the individual to change, or in
other words, its taking into account of stage differences.
In recent years many theorists and researchers have shown the
mismatch between the action-oriented physical activity programmes offered and the condition of the very sedentary population (mostly in precontemplation). Consequently, the
Transtheoretical Model has become influential in adult physical
activity. Many researchers have found evidence supporting the
use of the Transtheoretical Model for the understanding of
adoption and maintenance of exercise in adults. Two central
determinants useful in the application of the Transtheoretical
Model to physical activity are self-efficacy and the decision-balance between perceived benefits and barriers (pros and cons).
Marshall and Biddle (2001) showed in a recent meta-analysis
of 71 studies that there are sufficient data to confirm that stage
membership is associated with different levels of physical activity, self-efficacy, pros and cons, and processes of change.
Until now the utility of the Transtheoretical Model applied to
youth physical activity has not been studied extensively. Some
problems may be expected such as the higher levels of physical
activity in youth resulting in less people in the precontemplation and contemplation stages. In addition, the processes of
change may be different for adults and young people.
Moreover, it is not clear whether the decision-making model is
relevant for children. This concept might stress cognitive considerations and rational choices too much, not taking environmental factors sufficiently into account. Children are also
engaged in some compulsory physical activity in physical education, making it difficult to fit in to the concepts of the
Transtheoretical Model. However, because of the promising
results using the Transtheoretical Model in adult populations,
the investigation of its application to physical activity in children and adolescents, and how the model might be adapted for
youth, should be encouraged.
17
revista
19.9.03
0:49
Página 18
Invited speakers
Nigg & Courneya (1998) examined the applicability of the
entire Trantheoretical Model for adolescent exercise behaviour.
A sample of 819 students was recruited through grades 9 to 12
(mean age was 15.0 years). They found that the distribution of
the sample across the stages was 2.1% in precontemplation,
4.2% in contemplation, 28.% in preparation, 15.7% in action
and 49.3% in maintenance. They found preliminary evidence
for the applicability of the Transtheoretical Model to adolescents, with significant differences of the construct across
stages. However, low rates of adolescents in the precontemplation and contemplation stages were found. As they only had a
61% response rate, it is possible that nonexercisers did not
want to fill out a questionnaire about exercise. The premier
goal of Nigg & Courneya (1998) was not to supply accurate
estimates of the population prevalence in each stage. However,
they suggest that in the future more representative sampling
should be employed.
Hausenblas et al. (2002), Walton et al. (1999), and Cardinal et
al. (1998) focused on the applicability of the Transtheoretical
Model in younger children, resp. Middle school children, fifthand sixth-graders and first- through fifth-graders. Distribution
across stages was very different with over 87% in action and
maintenance in the youngest age group (Cardinal et al., 1998),
60% in the fifth- and sixth-graders (Walton et al., 1999) and
about 88% in the young adolescents (Hausenblas et al. 2002).
However, most samples were relatively small and none of them
were representative for the population. All authors argue for
studies in large, more representative samples before the validity and generalizability of the Thanstheoretical model in young
people can be accepted.
At the Ghent University, a study was executed to examine the
validation and usefulness of the Transtheoretical Model, and
more specific of the Stages of Change in a sample of adolescents (De Bourdeaudhuij et al., submitted). A random sample
of secondary schools was drawn in Flanders, the Dutch speaking part of Belgium.
A large sample of adolescents (n=6117) participated in the
study, all following secondary education. Their mean age was
14.8 (±1.9) and 61.1% were females. All students completed a
computerised questionnaire including physical activity and psycho-social determinants. The questionnaire was validated in a
previous study with CSA accelerometers (Philippaerts et al.,
2003). The instrument showed good test-retest reliability and
adequate validity.
Distribution of the sample across the stages was: precontemplation, n=684 (11.5%); contemplation, n=948 (16.0%);
preparation, n=818 (13.8%); action, n=492 (8.3%); and maintenance, n=2989 (50.4%). Results showed sex (p<0.001) and
age (p<0.001) differences across stages, with girls and older
adolescents being more prevalent in earlier stages. Multivariate
analysis of variance and univariate follow-up tests, controlled
for sex and age, showed that stages of change were distinguished by hours of sport participation per week in leisure
time, by hours of sport participation at school outside physical
education, and by hours of transportation per week. Analyses
of variance further showed that psychosocial variables consistently varied as function of stage classification: those in earlier
stages reported less positive attitudes, less social support, less
self-efficacy, less benefits and more barriers related to physical
activity (all mean scores gradually increased with higher stages,
for all p<0.001).
The results of this study provide support for the usefulness of
18
the stages of change algorithm related to physical activity in
adolescents. Intervention strategies focussing at the promotion
of physical activity in adolescents can be based on stages of
change and use the relevant constructs in each stage.
References
Cardinal BJ, Engels HJ, ZhuW (1998). Application of the
Transtheoretical Model of behaviour change to preadolescents’ physical
activity and exercise behaviour. Pediatric Exercise Science, 10, 69-80.
De Bourdeaudhuij I, Crombez G, Philippaerts R, Matton L, Wijndaele
K, Lefevre J. Stages of change for physical activity in a representative
adolescent sample. Submitted for publication.
Hausenblas HA, Nigg CR, Symons Downs D, Fleming DS,
Connaughton DP. (2002). Perceptions of exercise stages, barriers selfefficacy, and decisional balance for middle-level school students. Journal
of Early Adolescence, 22, 436-454.
Marshall SJ, Biddle SJH (2001). The Transtheoretical Model of
Behavior Change: A Meta-Analysis of applications to physical activity
and exercise. Annals of Behavioral Medicine, 23, 229-246.
Nigg CR, Courneya KS (1998). Transtheoretical Model: Examining adolescent exercise behaviour. Journal of Adolescent Health, 22, 214-224.
Philippaerts R, Matton L, Wijndaele K, De Bourdeaudhuij I, Taks M,
Lefevre J (2003). Reliability and validity of a computer-assisted physical activity questionnaire for 12- to 18-year old boys and girls: a preliminary study. Paper presented at the 8th Annual Congress of the
European College of Sport Science, Salzburg, Austria, 9-12July.
Prochaska, J., & DiClemente, C. (1983). Stages and processes of selfchange of smoking : toward an integrative model of change. Journal of
Consulting and Clinical Psychology, 51, 390-395.
Walton J, Hoerr S, Heine L, Frost S, Roisen D, Berkimer, M(1999).
Physical activity and stages of change in fifth and sixth graders.
Journal of School Health, 69, 285-289.
EFFECTS OF BODY FAT ON CARDIOVASCULAR FITNESS IN YOUTH
Rowland Thomas
Department of Pediatrics, Baystate Medical Center, Springfield, MA, USA.
Degree of body fat content has often been associated with
one’s level of cardiovascular fitness. In particular, excessive adiposity is expected to profoundly depress aerobic capacity. High
body fat content lowers weight-relative maximal aerobic power
(VO2max per kg) and diminishes functional fitness, such as
the ability to perform in distance running events. In the first
situation, VO2max per kg is lessened largely because body fat
inflates the denominator (i.e., body mass), while in the latter,
excess fat acts as an additional load which must be transported
during weight-bearing physical activities. In addition, both of
these factors may be further decreased by the sedentary
lifestyle often adopted by overweight persons.
Certain cardiovascular anatomic features are typically observed
in obese children and adults. These individuals have a greater
left ventricular size and mass as well as expanded plasma volume, and these characteristics translate into a greater resting
cardiac output and stroke volume compared to nonobese individuals. Such findings have been attributed to adaptations to
the high metabolic demands of the obese state. Persons with
moderate obesity usually tolerate this high output state well,
but those with long-standing morbid obesity eventually display
revista
19.9.03
0:49
Página 19
Invited speakers
systolic and diastolic dysfunction and congestive heart failure.
This is compounded by both pulmonary and systemic hypertension that are common in these individuals.
The effects of obesity on cardiac functional reserve itself are
not clear. Some information, both in adults and children, indicates that absolute maximal oxygen uptake is higher in overweight persons, indicating that depressed aerobic fitness is not
a reflection of any decline in cardiac capacity. In fact, these data
would suggest that if cardiovascular fitness is defined as the
maximal ability of the heart to generate cardiac output, the
obese subject actually possesses greater cardiac functional
reserve than the nonobese. There is evidence to suggest, too,
that this increase in cardiac output is a reflection of increase in
lean body mass, typical of the obese individual, rather than his
or her greater body fat content.
This information is of practical importance to those designing
therapeutic exercise programs for obese youth. If true cardiovascular fitness of the obese person is not reduced, such programs can focus on low-level, acceptable activities that raise
caloric expenditure rather than using more intense interventions that would be needed to augment cardiac function.
We recently compared cardiac responses to a progressive cycle
exercise test in 13 moderately obese adolescent girls (mean age
13.6+1.5 years) to those of non-obese teenagers. Body mass
index of the obese subjects ranged from 30 to 43 kg/m2. Peak
oxygen uptake, both absolute and relative to height3.0, was significantly greater in the obese compared to the control subjects. This difference was explained by a higher peak cardiac
output and stroke volume in the obese when values were
expressed in absolute terms or in respect to height3.0. No significant differences were observed when cardiac variables were
adjusted for body surface area. The pattern of rise in stroke volume and peak aortic velocity, markers of myocardial performance, were identical in the two groups. Resting echocardiograms showed that mean left ventricular end-diastolic dimension was significantly greater in the obese, but shortening fraction values were similar to those of the nonobese.
These data confirm previous information in adults that low aerobic fitness in moderately obese adolescents (as indicated by
depressed peak VO2 per kg body mass and limited endurance
performance), does not reflect decreased cardiac functional
capacity. In fact, the obese individual responds to greater body
fat and lean mass content by an increase in cardiac functional
capacity, characterized anatomically by a larger left ventricular
size. The mechanism for this response is unknown.
At the other end of the body composition spectrum are those
youth with anorexia nervosa, who are characterized by an
often-times dramatic decrease in body fat and lean mass.
Adolescents with anorexia typically demonstrate bradycardia,
low blood pressure, small heart size, and diminished resting
cardiac output. Endurance fitness is usually depressed, with a
low VO2max, heart rate, and blood pressure responses to a
standard exercise test. These features have been considered
secondary to a decrease in sympathetic tone.
Certain other cardiac characteristics have been observed in
some patients with anorexia that are of greater concern.
Prolonged QT interval, dysrhythmias, and ischemic-like ST
changes on the electrocardiogram have been described. Since
sudden death can be a complication of anorexia, the cardiac
features of these patients have received particular attention.
Little information is available, however, regarding their cardiac
responses to exercise. There is reason, however, to suspect that
cardiac reserve might be limited: normal myocardial performance is contingent upon adequate sympathetic nervous stimulation, circulating catecholamines, and energy substrate, as well
as normal mass and functional integrity of myocardial tissue.
Using the same protocol as in the study of the obese subjects
described above, we evaluated cardiac responses to a progressive
cycle exercise bout in eight girls (mean age 16.3+2.7 years) who
satisfied standard diagnostic criteria for anorexia nervosa of moderate severity. Resting and maximal heart rates were reduced in
the patients compared to healthy controls, and VO2max was subsequently lower. Maximal stroke index was greater in the patients
than the controls. Pattern of stroke volume response, peak aortic
velocity, and mean acceleration of flow were similar in the two
groups when adjusted for heart rate.
This study confirmed findings of diminished heart rate and aerobic fitness previously described in patients with anorexia nervosa. However, there was no evidence of abnormal myocardial
performance during maximal exercise testing. The cardiac
responses to exercise which were unique to the anorexia
patients appeared to be related entirely to a dampened
response of heart rate to exercise. This chronotropic response
could be related to lower sympathetic tone, but, if so, this
autonomic alteration did not influence other circulatory
responses to exercise.
The combined data regarding the responses of young individuals
with body fat content ranging from moderate obesity to moderately severe anorexia nervosa suggest that body fat itself does
not negatively influence cardiac functional capacity. Future studies in youth with more serious levels of obesity and anorexia will
be important in determining if cardiovascular fitness is adversely
impacted when these conditions become more extreme.
ASTHMA AND EXERCISE
Vaz Maria LG
Faculty of Medicine, University of Porto, Portugal
In the last years, asthma has become the most prevalent chronic disease among children and adolescents, affecting up to 10%
of them.
Exercise has long been known as a common and potent trigger
of asthma attacks.
Exercise induced asthma (EIA) affects 70 – 80% of all asthmatics
and its prevalence among school children is about 19 to 23%.
In 40 % of children with demonstrable EIA no clinical diagnosis has been made, showing how unprepared we all still are –
doctors, nurses, teachers and parents. The fact that breathlessness, wheezing or cough, the clinical picture of EIA appear
almost 10 minutes after stopping the effort and not during
exercise, may explain the magnitude of under diagnosed EIA.
Anyway, it is well controlled in 50 to 65% of the patients, and
many competition athletes have this form of disease.
It’s defined as a transient reduction of lung function that
occurs after vigorous exercise, with a fall of FEV1 and the previous levels are reached after 20 to 60 minutes of rest.
The rationally of EIA is not fully understood, and there is still
some arguing going on, but it seems that loss of heat and
water by the respiratory tract play the most important role.
The recognition of EIA is very, very important because full par-
19
revista
19.9.03
0:49
Página 20
Invited speakers
ticipation in sporting activities is a goal in the management of
childhood asthma. With medication before exercise (usually a
short acting Beta 2 – agonist), a warming period and a progressive increase in it’s duration, the asthmatic patient will probably be able to practice any kind of sports.
It must be considered a crucial part of treatment, not only
improving lung function with time, but also self-esteem and
making real the possibility of being “part of the group”.
Also specified exercises, directed to the respiratory rehabilitation, and teaching the children how to breath during an asthma
attack are part of the treatment, as important as the prescription of the medication.
So there is a dual relationship between asthma and exercise,
being exercise a way of improving lung function but also still
the most common trigger of asthma attacks.
in particular, psychosocial barriers. The literature is less clear
as to whether juvenile obesity is accompanied by reduced daily
energy expenditure. Some of this inconsistency reflects the
way energy expenditure is calculated.
While enhanced physical activity has little or no effect on adiposity of non-obese children and youth, it is an important element in the treatment and, possibly, in the prevention of juvenile obesity. Some of the benefits affect body composition.
Others include increased insulin sensitivity, reduction in arterial blood pressure, improved plasma lipid profile and in selfesteem, as well as increased physical fitness.
THE JUVENILE OBESITY EPIDEMIC: IS PHYSICAL ACTIVITY
RELEVANT?
Kemper Han CG, Koppes LLJ
Bar-Or Oded
Children’s Exercise & Nutrition Centre, McMaster University,
Hamilton, Ontario, Canada
The last two decades have seen a major surge in the prevalence
of childhood and adolescence (“juvenile”) obesity. With the
spread of this condition in numerous countries, the World
Health Organization has termed it a Global Epidemic.
Concurrently, there has been an increase in the incidence and
prevalence of insulin resistance and even in overt type 2
(“adult onset”) diabetes mellitus in obese adolescents and children. One also sees a surge in, among others, dyslipidemia
and polycystic ovarian syndrome.
While such a rise in the prevalence of juvenile obesity reflects a
progressively increasing positive energy balance, the causes for
this are not entirely clear. In some societies, particularly those
that used to suffer from undernutrition, this surge reflects an
increase in energy intake, secondary to improved accessibility
to nourishing food. Children who undergo improved energyprotein nourishment show, at least initially, an increase in body
mass, with little or no increase in body stature. As a result,
their Body Mass Index increases and some are categorized as
“overweight” or “obese”. There are few epidemiologic data to
tell whether children and youth in technologically developed
countries have undergone a secular increase their energy consumption in the last two decades. One study, based on a US
nationwide sample, suggests that several age groups had a
reduction in the percentage of fat in their diet.
Another plausible reason is an increase in sedentary pursuits
and a decrease in active pursuits among children and youth.
While more epidemiologic evidence is needed to substantiate
this theory, young people in many countries spend much of
their leisure time on sedentary “activities” such as the Internet,
computer games, video and TV. There is compelling evidence
for a strong association between the risk of being obese and
the amount of time spent on watching TV, among US adolescents. Likewise, the likelihood for remission from obesity over
time is inversely related to the amount of TV watching.
As a group, obese children and adolescents are less active than
their non-obese peers. This may be explained by physical and,
20
THE AEROBIC FITNESS AND PHYSICAL ACTIVITY PARADOX:
ARE WE FIT BECAUSE WE ARE ACTIVE, OR ARE WE ACTIVE
BECAUSE WE ARE FIT?
VU University Medical Center, Institute for Research in Extramural
Medicine, Vrije Universiteit, Amsterdam, The Netherlands
Introduction
Multiple randomized controlled trials have demonstrated that
in males and in females, in children and adults the physical fitness can be improved by effective physical activity programs.
All these training studies however, are relatively short in duration (from 6 weeks to 12 months) and most of the time in
populations of healthy volunteers. These results can therefore
be confounded by self-selection. Moreover the short-term
effects of these training programs are not indicative for lifetime
changes of physical activity patterns on physical fitness.
Lifetime intervention studies, even if these are performed over
several years, are not feasible and also not ethical in human
populations.
Positive relationships between physical activity and physical fitness in children as well as in adults are often demonstrated by
significant correlations in cross sectional studies. However in
these studies the correlations do not indicate the direction of the
relationship: a high correlation between activity and fitness can
be explained in both ways: the population under study is more
physically fit because they are more active or the other way
around: the population is more active because they are more fit.
One way to come out of this dilemma is to do a prospective
observatory study in a population and to compare fitness and
in subpopulations of subjects who showed during the observation period respectively relatively low and high physical activity
patterns.
Methods
In the Amsterdam Growth and Health Longitudinal Study
(AGAHLS) ca 300 boys and 300 girls at age 13 years, were followed over a period of almost 25 years till age 36 years
(Kemper, ed., 1985; Kemper, ed., 1995) with a maximum.
revista
19.9.03
0:49
Página 21
Invited speakers
Figure 2: Standardized regression coefficients and p-values
obtained by GEE regarding the longitudinal relationship
between physical activity and maximal aerobic power
Figure 1: General design of the AGAHLS, with time of
measurement (horizontal axis) and mean calendar age
(vertical axis) of the study cohort.
Physical activity and aerobic fitness were measured repeatedly
at least three times and maximally nine times. Physical activity
was measured by a cross-check interview (Montoye et al, 1996)
estimating weighted metabolic energy expenditure (MET
score) during the three previous months, and aerobic fitness
(Kemper et al, 1976) by a maximal treadmill test (running at
8km/hour with increasing slope) while measuring directly and
continuously the maximal oxygen uptake from expired air
(VO2max).
To get an indication of a possible long-term effect of these patterns of activity on aerobic fitness a different longitudinal
analyses were carried out, correcting for possible confounders
such as other lifestyle (dietary intake, alcohol and smoking
behaviour) and biological variables (biological age, percentage
body fat, serum cholesterol and blood pressure).
The statistical analysis used was generalized estimating equations (GEE) (Zeger et al, 1986), in which the longitudinal relationship was analysed including all available physical activity
and aerobic fitness data with adjustment for both time dependent (biologic and lifestyle variables) and time independent
covariates (gender).
Because the aerobic fitness at the start of the study could have
biased the effect on physical activity, in one GEE analysis was also
adjusted for differences in initial aerobic fitness at age 13 years.
In a second GEE analysis an autoregressive model was used, in
which the longitudinal relation of present physical activity on the
VO2max value of the next measurement was calculated.
Results
From the results it can be concluded that over the 25 years
period of follow-up the development of aerobic fitness between
13 and 36 years of age is independently and positively related
to daily physical activity in both sexes (p<.01). This relationship was significant in the crude model as well as in the models adjusted for lifestyle and adjusted for biological parameters.
However, the functional implications of the highly statistical
significant relationships seem to be small: a 10% difference in
MET-score was positively related to a 0.3% difference in
VO2max.
In contrast, the results of the autoregressive model in which
was controlled for present VO2max, reveal no significant relations between physical activity and aerobic fitness over the
period of follow-up in both sexes over the 13-36 years age period: a difference in physical activity of 10% appeared to be positively related to a non-significant difference in VO2max of only
0.04% (95%CI: -0.06 to 0.13).
Figure 3: Representation of the autoregression model of present physical
activity (PA) on future aerobic power (VO2max) with correction for
present VO2max. Numbers represent the mean calendar age of the population at the nine points of measurements.
Conclusion
The longitudinal data from AGAHLS do not fully support the
hypothesis that physical activity effects aerobic fitness.
This may indicate that that genetic factors are more important
for aerobic fitness than environmental factors such as daily
physical activity (Joyner, 2001).
References
Kemper HCG, Binkhorst RA, Verschuur R, Visser ACA (1976).
Reliability of the Ergoanalyser. J Cardiovasc Technology; 4:27-230.
Kemper HCG, editor (1985). Growth, Health and Fitness of
Teenagers, longitudinal research in international perspective. Medicine
and Sport Science vol 20 Karger, Basel. ISBN 3-8055-4042-6.
Kemper HCG, editor (1995). The Amsterdam Growth Study, a longitudinal analysis of health, fitness, and lifestyle. HK Sport Science
Monograph Series Volume 6. Human Kinetics, Champaign, IL. ISBN
0-87322-507-4.
Montoye HJ, Kemper HCG, Saris WHM, Washburn RA (1996).
Measuring physical activity and energy expenditure. Human Kinetics,
Champaign, IL: 183-184. ISBN 0-87322-500-7.
Joyner MJ (2001). ACE genetics and VO2max Exercise and Sport
Sciences Reviews, vol 29, 2: 47-48.
Zeger SL, Liang K-Y. Longitudinal data analysis for discrete and continuous outcomes. Biometrics1986; 42:121-130.
21
revista
19.9.03
0:49
Página 22
Invited speakers
Acknowledgements
The authors like to thank the participants who served in the
study for almost 25 years and the members of the AGAHLS
research team for their effort to collect the data, cleaning the
longitudinal data base and prepare them for data analyses.
MUSCLE-BONE MUTUALISM, MECHANICAL LOADING AND
THE MECHANOSTAT THEORY: A PEDIATRIC PERSPECTIVE
Blimkie CJR1, Högler W2
1 Department of Kinesiology, McMaster University, Hamilton,
Ontario, Canada
2 Institute of Endocrinology and Diabetes, The Children’s Hospital at
Westmead, Sydney, Australia
Introduction
The mechanostat theory is an evolving paradigm that describes
the putative interplay between mechanical loading and skeletal
adaptation in animals and humans (3). The paradigm incorporates a biological model of feedback control consisting of
mechanical strain sensors, bone cell transduction mechanisms
and mechanical loading or strain thresholds. The function of
this feedback mechanism, by mobilizing bone modeling,
remodeling and growth, is to normalize activity-related increases in bone strains, to within their homeostatic range. In this
model, mechanical loading effects on bone, although predominant, may also be modulated by genetic, nutritional, and hormonal influences. Mechanical loading in this context refers to
bone strains engendered either directly or indirectly from muscle contractile forces during physical activity or exercise. The
purpose of this review is to examine the role of muscle forces,
independent of other loading characteristics of physical activity,
in inducing skeletal adaptations in children and adolescents.
The review focuses on certain operational features of the
mechanostat model, that are perhaps more peculiar or relevant
to the young growing, than to the fully developed adult skeleton. The implications of the peculiar pediatric features of this
model will be discussed in relation to research study design
considerations that are required to advance our understanding
of the muscle-bone interaction (mutualism) within the context
of this model.
The Mechanostat — A Brief Review
The mechanostat theory stipulates that the magnitude of the
skeletal adaptive response will vary according to the “change”
in mechanical strain history in relation to three intrinsic bone
strain (ε) thresholds: the minimum effective strains for remodeling (MESr), modeling (MESm) and microdamage (MESp).
Strain is synonymous with a change in bone length from its
unloaded state e.g. 1000 uε = 0.1 % change in bone length. In
children, mostly because of the influence of increasing body
mass, even normal daily activities will induce mechanical
strains in bone that approach or exceed the MESm. Strains
within the MESr-MESm range (adapted window or comfort
zone), may therefore increase modeling (and perhaps even
growth) in children, depending on modulating factors like
growth rate, nutrition and hormone status. The skeleton
adapts to the increased strain levels with net increases in bone
mineral accrual and concomitant changes in bone structure
22
(geometry, size and shape). The high level of modeling activity
during childhood favors loading related changes in bone structural properties. Compared to adults, normal healthy children
operate further to the right within the adapted window (comfort zone), or somewhere within the mild overload window,
depending on background modulating factors like activity level
and growth rate. Muscle force engendered in physical activity,
exercise and sport is considered a major modulator of bone
strain and resulting osteotropic adaptive responses to loading
in children.
Muscle-Bone Mutualism
Intuitively, given their shared functional role in movement, one
might anticipate close coordination in the growth and development of both skeletal muscle and bone: the muscle-bone unit
(4). Skeletal development in the very early stages of pre-natal
growth, however, appears driven by intrinsic regional growth
and genetic factors, initially presumably independent of direct
mechanical strain associated with muscle activity. Once the
muscle-bone unit is anatomically established, muscle forces
begin to induce strain in bones even in-utero, as evidenced by
underdeveloped and even fractured bones in certain neuromuscular or bone mineral disorders. The magnitude of muscle
induced mechanical strain is potentiated in the transition from
pre-natal to post-natal life, due to the influences of gravity and
physical activity-associated muscle force requirements acting
against an increasing body mass. Besides the obligatory coordinated increases in muscle lengths with increasing bone lengths,
post-natal development of the morphological features of the
muscle-bone unit is not as tightly coordinated as might be
expected (5). The proportion of muscle mass increases, whereas that of bone decreases with growth, along with regional
variation and sexual dimorphism in the distribution of the proportions of muscle and bone.
Due to poor mechanical advantage (force arm < resistance arm
in most muscle-bone units), however, especially in weight
bearing bones, muscle forces acting on the skeleton in humans
are generally quite large, usually exceeding by far the peak
ground reaction impact forces associated with extreme loading
conditions such as tumbling in gymnastics (3). Theoretically
then, activity associated contractile forces of muscles acting on
bones may be considered an important determinant of bone
strain and skeletal adaptation within the context of the
mechanostat theory in growing children. Besides the expected
close coordination of bone and muscle length changes, development of other morphological characteristics, for example,
muscle and bone cross-sectional areas, may be less closely correlated. These characteristics may be more dependent on external factors such as ground reaction forces, activity histories,
magnitude, rate and type of loading strains, and their interaction with intrinsic systemic and tissue specific endocrine factors. Muscle force and bone strength (under certain loading
conditions) are related to their respective cross-sectional areas,
which are in turn related to body size. Hence, some association
might be expected between gross morphological and functional
measures of muscle size with structural factors influencing
bone strength in children during growth.
Muscle Force, Bone Strain and the Mechanostat
Theoretically, the mechanostat sensor is unaware of, and incapable of differentiating the source of the load, responding only
to local or regional changes in detectable strain levels. The
revista
19.9.03
0:49
Página 23
Invited speakers
osteotrophic effector response, however, is sensitive to the
parameters of the loading stimulus which influence strain,
including the magnitude, rate, frequency and latency of the
applied loads. In humans, bone strain derives from three predominant sources: ground (during weight bearing activity) and
joint reaction forces, that vary proportionately as a function of the
mass of the body or body part moved and its acceleration in
gravity and muscle forces acting on bone. Muscle forces also vary
in proportion to the mass being moved (inertia and any externally applied loads), but are also dependent on the mechanical
advantage of the muscle-bone unit (7). Muscle forces engender
bone strain both locally at tendon insertion points, as well as
along the lengths of bone, causing mostly bending moments.
The absolute and relative contributions of these sources of
strain to bone will vary by activity type, intensity, and training
history, age, sex and maturity-related influences on body size
(mass mostly). Experimentally, it is difficult to isolate the
exclusive contribution of muscle forces to bone development,
since muscle mass comprises a variable but substantial proportion of body mass during growth, thus also contributing to
strain engendering ground and joint reaction forces.
Furthermore, absolute growth of both muscle and bone co-vary
with changing body mass during childhood, precluding easy
differentiation of the unique influence of muscle size and force.
Lastly, there are several muscle-bone unit phenomena such as
regional myoelectric and circulatory influences that may,
because of their shared anatomical and functional relationships, influence skeletal development independent of the influence of muscle contractile forces. While it is difficult to differentiate and quantify the independent contributions of these
putative modulators of strain, variation in muscle forces acting
on bone apparently explain upwards of 50% of the post-natal
variability in development of bone strength and mass in
humans (4).
Strain Engendering Bone Loading Conditions
Normal activity in humans results in skeletal loading under
conditions of mostly bending and compression, with a lesser
degree of torsion. Because of the curvature of most weightbearing bones and the biarticular nature of many of the muscle
arrangements, physical activity apparently imposes mostly
bending loads on the skeleton, accounting for more than 80%
of the total bone strain load. The nature of the predominant
loading condition during activity is important, because it predicts whole as well as regional bone strain distribution patterns
and ultimately the amount and type of expected osteotrophic
adaptive response. The loading condition in turn determines
the location and functional effectiveness of regional skeletal
adaptive responses. For example, bending loads impose high
tension and compression strains respectively, on the convex
and concave portions of long hollow bones, predicting larger
adaptations on these surfaces than on the inner surfaces of the
bone where strains along the neutral axis are lowest. Further,
the osteotrophic adaptive response to activity induced strain is
multi-varied, including possible alterations in the bone’s material or structural properties, which separately or in combination attempt to bring the regional strain distribution level back
to within its normal range. These adaptations ultimately
increase bone strength under the imposed loading condition.
Mechanically, the strength of bone is dependent on its material
and structural (geometric and biomechanical) properties, their
relative importance varying under differing loading conditions
(2,6). Under bending loads, bone strength is largely dependent
on its material (including its mineral content), geometric (size
and material distribution) and biomechanical properties (crosssectional moment of inertia-CSMI). Under axial compression,
bone strength is largely dependent upon its material properties
and its cross-sectional area for dispersion of load bearing.
Torsional bone strength by comparison is dependent largely upon
its polar moment of inertia (PMI), material composition and
radius. The influence of muscle forces on the various properties of bone, therefore, will depend on the magnitude and type
of loading condition-specific strains imposed both globally and
regionally by the activity. The specificity of these interactions
suggests that no single in vivo osteotrophic measure will adequately or accurately reflect the skeletons’ adaptive response to
loading under the myriad conditions that characterize human
movement. Furthermore, knowledge of the nature of the predominant loading condition sub-served by the muscle-bone
unit, and the specific mechanical correlates influencing bone
strength under these conditions will facilitate selection of the
most physiologically relevant bone outcomes. It follows, therefore, that non-invasive studies investigating the importance of
muscle force as a modulator of skeletal adaptation to exercise
in children must include an array of measures including both
the material and structural properties of bone to ensure accurate interpretation (8).
Muscle Force and Bone Measures
Investigations of musculo-skeletal development in children
have typically assessed muscle force as muscle group specific
isometric, isotonic or isokinetic strength or torque measured
by dynamometry. With the advent of non-invasive imaging
techniques (e.g. dual energy x-ray absorptiometry-DXA,
peripheral quantitative computer tomography-pQCT or magnetic resonance imaging-MRI), lean tissue mass (LTM) and
muscle size (CSA and volume) determined using these
approaches have sometimes served as perhaps more reliable
surrogates of muscle strength. The use of these surrogates recognizes the close physiological relationship between muscle
size and its force producing capacity.
Until recently, the majority of studies investigating the musclebone unit in children have related muscle force or size measures to bone mineral content (BMC) or areal bone mineral
density (aBMD), both measures of the material properties of
bone, and to bone area (BA), a measure of bone geometry,
determined by DXA. With DXA, BMC, aBMD and BA are all
body size dependent, making it difficult to differentiate the
independent influence of muscle strength and size, which
themselves are size dependent. Furthermore, aBMD does not
represent the volumetric density of the various bone compartments (bone organ, cortical or medullary compartments) and
BA reflects the distribution of bone only in the anterior-posterior plane, not reflecting its true circumferential distribution.
Recent advances with DXA technology (Hip Strength Analysis
software) have permitted estimates of regional geometry (CSA)
and biomechanical properties (cross-sectional moment of inertia-CSMI and section modulus) of bone based on assumptions
of a cylindrical model of bone shape. In addition, MRI and
pQCT permit determination of bone compartmental volumetric
BMD (g/cm3), geometry (e.g. circumferential CSA of the entire
bone region or its cortical shell and medullary cavity), bone
biomechanical properties (e.g. CSMI or PMI), integrated measures of bone material and biomechanical properties (e.g. bone
23
revista
19.9.03
0:49
Página 24
Invited speakers
strength index-BSI) as well as region or site specific measures
of muscle CSA or volume. The emergence of these newer and
more accurate, reliable and safer non-invasive muscle and bone
assessment technologies will clarify and enhance our understanding of the interaction between muscle forces and skeletal
adaptation both in healthy children and in children with chronic disease or disability.
Muscle Force — is it a major determinant of skeletal
adaptation in children?
The muscle-bone unit has not been extensively investigated in
pediatric populations. The influence of muscle force and size
has been examined using a variety of analytical procedures
including simple correlation, multiple regression and principle
components analysis for both population and cross-sectional
comparative studies of groups differing in sport or exercise
training background. The relationship appears to be highly
complex, varying by anatomical site, age, sex, maturity, sport
specialization and bone outcome measure. For bone mineral
outcomes (BMC and aBMD), associations in children are generally weak to moderately strong in population studies and
vary between significant and non-significant within specific age
and sport groups. In these studies, strength sometimes
accounts for a significant but nevertheless relatively small proportion of the variability in BMC or aBMD across collapsed
groups, even when there are no significant inter-group differences for strength measures or differences in bone mass among
strength quartiles. Further, although still controversial, there is
some suggestion of a maturity related sexual dimorphism
favoring females in the development of the muscle-bone relationship around puberty, with higher total body BMC per LTM
(just to be consistent) in post-pubertal girls compared to prepubertal males and females and post-pubertal males. This latter maturity related relationship between LTM, a proxy for
muscle size and force, and BMC may, however, be artifactual,
simply reflecting sampling bias. Low to moderate site-specific
correlations have also been reported between forearm muscle
force and volumetric measures of total radial BMD, but not
volumetric trabecular or cortical bone BMD determined by
pQCT. Of the limited number of prospective studies involving
high intensity resistance or strength training, the association
between strength gains and changes in BMC or aBMD are weak
at best, and on a proportional basis, strength gains usually far
exceed gains in bone mass.
Even less is known about the relationship between muscle
forces and bone structural properties in children and adolescents. Again, most of the work in this area has focused on
comparisons among athletes representing different sports and
loading conditions. Generally, muscle strength of the legs
(quadriceps and hamstrings) has been reported to account for
significant proportions of the explained variation in some, but
not all bone areas determined by DXA, despite non-significant
differences in leg strength among adolescent sport groups. In
these comparative studies, leg strength was more strongly correlated with and accounted for the largest proportion of the
explained variation in total body BA, than more region specific
BA at the trochanter, proximal femur and tibia, with generally
weaker relationships among females. Grip strength has also
been reported to be weakly to moderately correlated with several measures of DXA determined distal and ultradistal radial
bone diameters, cortical thickness and biomechanical indices of
bone strength in peri-pubertal girls. Based on pQCT assess-
24
ment, slightly more favorable, moderate to strong site-specific
correlations have also been reported between forearm strength
(grip), geometric measures of total and cortical bone areas and
a biomechanical measure of bone strength index in mostly prepubertal boys and girls. In elite adolescent female athletes neither absolute, nor lean mass normalized leg strength (knee
extension and flexion strength or their ratio) were significantly
correlated with, or differentiated among MRI determined midfemur measures of bone geometry and biomechanical indices of
bending strength among swimmers, cyclists, runners and
triathletes.
Summary
Clearly, the theorized strong positive association between muscle size and strength and skeletal adaptation has not been consistently demonstrated in the pediatric bone and exercise
research to date. In the context of the mechanostat theory, the
influence of activity-associated muscle forces on bone must be
considered against the background of normal developmental
variation in the muscle size, strength and bone relationships.
Given the age, sex and maturity dependent variations in these
developmental relationships, it may be wishful thinking to
expect a simple monotonic relationship to describe the musclebone interaction, especially given the multi-faceted nature of
the skeletal adaptive response to exercise in children. Our
inability to confirm a strong muscle–bone relationship stems in
part from not appreciating the sophisticated interaction
between the nature of the loading conditions induced by muscle forces, the mechanical properties of bone responsive to the
condition-specific strain patterns, and consequently the best
outcome measure to assess the adaptive response.
Furthermore, for young athletes involved in specialized training, the skeletal adaptive response may also be influenced by
activity type (the relative strength requirements of different
sports), by the timing of the measurements of strength and
muscle mass compared to the measurements of bone (e.g. recognizing the lag time between bone and muscle strength adaptations) and by the nature of the predominant non-muscular
ground and joint reaction forces inherent in the training activity. Establishment of the dominance of muscle force in this relationship also requires proof of a strong association between
increased muscle size and strength and bone mass or size,
independent of body size influences: this has not been satisfied
in most of the pediatric studies to date. Establishment of cause
and effect requires proof of a temporal dissociation between
changes in muscle size or strength and changes in bone in
response to either increased or decreased loading (1). Clearly,
these are areas requiring further investigation and clarification.
Practical Applications
Unraveling the unique contribution of muscle forces to skeletal
adaptation is not merely a theoretical and intellectual exercise.
Understanding the operational characteristics of the musclebone relationship may improve exercise prescription for optimization of bone strength in normal healthy children and adolescents. Further, adapted exercise approaches focusing on
muscle strengthening activities may prove more effective for
rehabilitation of weakened or fractured bones that characterize
many chronic pediatric diseases and their pharmaceutical treatment strategies. Additionally, appreciation of the normal muscle force-bone relationship may enhance clinical differentiation
of “physiologic” osteopenia in pediatric disease (defined as low
revista
19.9.03
0:49
Página 25
Invited speakers
bone mass proportionate to inactivity-associated reductions in
muscle size and force) from osteoporosis, a deficit in bone
mineralization that reflects abnormal bone metabolism.
Improved diagnostic accuracy may result in improved and more
effective treatment strategies and enhanced recovery of bone
health status.
References
1. Burr, D.B. (1997). Muscle strength, bone mass, and age-related
bone loss.), J. Bone Miner. Res. 12:1547-11551
2. Forwood, M.R. (2001). Mechanical effects on the skeleton: are
there clinical implications? Osteoporos Int., 12: 77-83
3. Frost, H.M. (2000). Muscle, Bone and the Utah Paradigm: A 1999
overview. Med. Sci. Sports Exerc. 32 (5):911-917
4. Frost, H.M, and E. Schonau (2000).The “Muscle-Bone Unit” In
Children and Adolescents: A 2000
Overview. J. Ped. Endocrinol. Metab. 13: 571-590
5. Henning, S.W. (1994). Development of functional interactions
between skeletal and muscular systems. In: Vol.
9: Differentiation and Morphogenesis of Bone. B.K. Hall Ed., CRC
Press, Boca Raton
6. Martin, R.B. (1991). Determinants of the mechanical properties of
bones. J. Biomechanics 24 (Suppl. 1): 79-88
7. Turner, C.H. and D.B. Burr (1993). Basic Biomechanical
Measurements of Bone: A Tutorial. Bone, 14: 595-608
8. Van Der Meulen M.C.H., K.J. Jespen and B. Mikic (2001).
Understanding bone strength: size isn’t everything.
Bone, 29 (2): 101-104
SCHOOL AGE PHYSICAL ACTIVITY AS A PREDICTOR OF PHYSICAL
ACTIVITY IN ADULTHOOD 21 YEARS LATER
activity index was significant but low in all cohorts, in males
higher (0.29 - 0.39) than among females (0.16 - 0.27).
Multiple step wise regression analysis showed a little higher
predictability, R varying from 0.31 to 0.44 among males and
from 0.17 to 0.32 in females. According to r and beta coefficients the best predictors among individual variables were participation in sport club training sessions, participation in sport
competitions, vigorous physical activity and the grade of physical education. The effect of stability of physical activity at school
age on adult physical activity was studied categorising the subjects to those who had stayed in most active third of physical
activity index from 1980 to 83, and to those who had stayed in
most inactive third during same interval. Odds ratios showing
the probability to belong to the most active third as compared
to most inactive group 2001 were 4.3 (1.8 - 9.7) and 2.9 (1.3 6.4) among 9 -12-years-old boys and girls, and 7.1 (2.6 - 19.0)
and 5.6 (2.2 - 14.1) in 15 - 18-years-old boys and girls. When
persistent activity/inactivity from 1980 to 86 were compared
the probability was higher, OR varying from 5.9 to 10.8. In
addition it was found that activity tracks better than inactivity.
Physical activity at school age (9 - 18 years) predicts physical
activity at adult age 21 years later. The linear correlation
although significant is low, higher among males than females.
Long-term persistence of physical activity and persistent participation in competitive sport at young age increases the probability to be physically active in adulthood. The results emphasise
the importance of promoting physical activity at school age.
AGE AND GENDER DIFFERENCES IN PATTERNS AND TYPES
OF PHYSICAL ACTIVITY IN YOUTH
Mota Jorge
Telama Risto, Yang Xiaolin
Department of Physical Education, University of Jyvaskyla,
Jyvaskyla, Finland
Enhancing life-long physical activity has long been an important goal of physical education curricula and sport policy in
many countries. However, rather little is known how physical
activity in childhood predicts active lifestyle in adulthood.
Even less is known how the type and nature of youth physical
activity and sport participation are connected with physical
activity in adulthood. The aim of this paper is to investigate
how well type of physical activity and long term participation
in physical activity and sport participation at school age predict
physical activity in adulthood.
In 1980 2309 9-, 12-, 15- and 18-year-old boys and girls were
randomly sampled to be the subjects of this study (Young
Finns Study). The measurements were replicated in 1983,
1986, 1989, 1992, and 2001. In 2001 the subjects were respectively 30-, 33-, 36-, and 39-year-old (Åkerblom et al. 1985,
1999). Physical activity and participation in sports in 1980
were measured by means of a short self-report questionnaire.
Questions concerned the frequency and intensity of leisuretime physical activity, participation in both organized sports
and recreational sports. By summing up after re-coding these
variables the index of physical activity was calculated. (Telama
et al., 1985; 1997).
Rank order correlation for the 21 years tracking of physical
Research Centre in Physical Activity, Health and Leisure, Faculty of
Sport Sciences and Physical Education, University of Porto, Portugal
Introduction
Extensive evidence has documented the health benefits of regular physical activity (PA). Several studies have shown that
many of the known risk factors for chronic diseases are also
present in youth (Teixeira et al. 2001) and it has been suggested that inactivity during youth is linked to several health-related risks in adulthood (Twisk et al. 1997) On the other hand,
lifetime physical activity and the establishment of healthy patterns of lifestyle, in childhood tend to generate active adults
(Malina, 1996). General guidelines are widely used to describe
health-related PA benefits in youth addressing the important
role played by the moderate-to-vigorous physical activity
(MVPA) (Cavill et al. 2001). Moreover, during the last years a
debate concerning the health benefits and the characteristics of
the activity such as MVPA versus light activities, and intermittent versus continuous activity - address the need to assess not
only a general measure of activity but also the characteristics
and dimensions of the activities (e.g. intensity and duration)
(Sallis and Saelens, 2000). Because, usually policies and programs strategies are based on prevalence estimates for meeting
these guidelines, it is crucial that prevalence estimates be accurate (Sarkin et al, 2000). As researchers begin to explore the
PA dose-response relationship with health parameters, it is
increasingly important to provide a more precise estimate of
25
revista
19.9.03
0:49
Página 26
Invited speakers
both the quantity and the quality of PA. Therefore, would be
useful to provide a more complex and accurate understanding
of how children differ in their activity patterns (Janz et al.
1995). The mechanisms beyond those facts are confusing,
because participation in physical activity appears to be influenced by a large number of factors, including environmental,
social and psychological variables. Age and sex are the two
most studied biological covariates of participation in physical
activity in youth. In fact age-related changes depend on physical activity type and characteristics (Telama, et al. 1994), and
research findings support the idea that physical environments
are closely associated with physical activity (Owen et al.,
2000). However, the question whether patterns of PA, during
specific periods of time, are or are not representative of the
entire day’s PA patterns is still unanswered (Trost et al. 2000).
One way to approach this issue may be to focus the assessment
of PA on key times or places that allow youth to be active. This
is a timely topic and an answer can guide the development of
measurement protocols in field-based studies that are needed
to investigate high priority issues related to youth PA.
Furthermore, the influence of participation in structured or
unstructured programs has not been well quantified during
adolescence. In fact, few studies have examined the differences
among groups with different PA participation levels (from
sedentary to high level of physical activity). Thus structured vs.
unstructured activities choices is a research interesting area
because such contributions are extremely important to develop
effective physical activity interventions in youth.
p=0.001) than among boys (χ2 = 7.762, p=0.05). Our findings
also showed that there are changes in the nature of physical
activity choices across adolescence. The tendency reported for
the frequency rate of adolescents not participating in structured activities seems to confirm those ideas. We reported a
significant decrease in the tendency for non-oriented sports
participation with increasing age. However, no differences in
the tendency of the formal sports participation were found.
Purpose
According to the age and sex:
1 — Identify patterns of MVPA in youth
2 — Identify places of MVPA participation during school period
3 — Determine whether there are specific periods of the day
that could be representative of MVPA participation
4 — Determine the associations with choice of structured and
unstructured physical activity programs outside school
References
Cavill N et al (2001). Ped Exerc Sci. 13:12-25.
Janz KF et al (1995). Med Sci Sports Exerc 27(9):1326-1332.
Malina RM (1996). Res Quart Exerc Sports 67(3 suppl.):S48-S57.
Owen, N et al (2000). Exerc. Sport Sci. Rev., 28(4): 153-158.
Sallis JF, Saelens BE. (2000). Res Quart Exerc Sports 71(2 suppl):
S1-S14.
Sarkin JA et al (1997). J Teach Phys Educ 17:99-106.
Teixeira PJ et al (2001). Obes Res 9(8):432-442.
Telama, R et al (1994). Scandinav. J. Med. Sci. Sports 4(1): 65-74.
Trost S et al (2000). Med Sci Sports Exerc 32(2):426-431.
Twisk JWR et al (1997). Am J Epidem 145:888-898.
Results
Data from our research showed that PA was consistently higher in boys than in girls.. The findings also support the idea that
from a public health perspective children appear to meet the
minimum PA recommendations for health. Regarding the
engagement in MVPA it was not possible to found any clear
pattern of PA. Girls, showed higher percent of time engaged in
MVPA during the morning and early afternoon periods (sum of
two periods 51.0%), while boys’ percent of time engaged in
MVPA is higher at late afternoon and evening periods (sum of
two periods 53.8%). A principal components analysis showed
four distinct components that accounted for 67% of the variance, indicating that within each time component, students’
participation in MVPA remained consistent yet distinct from
other times during the day. The results showed an important
period of MVPA participation, corresponding to the school
hours (component 1) and another important key period, corresponding to lunchtime and outside-school activities (component 2). Morning time before school period (component 4) and
period before bedtime (component 3) appear as distinct periods of daily time. Our data pointed out that, in adolescents,
participation that there is an increase in structured physical
activity participation as the physical activity level increases.
The differences were greater among girls (χ2 = 20.663,
26
Conclusion
From a public health point of view, our data suggested that
lunchtime and after-school periods (afternoon) might be an
appropriate target for PA intervention programs. It was interesting to observe that lunchtime has been associated with outside school activities, which suggest lunchtime as an important
period of engagement in MVPA, likely spontaneously.
Girls tend to be more active during school periods, while boys
are more active after school.
Only 33% of adolescents participated in structured physical
activities out side school.
As age group increases, sports activities become a relatively
more important component of total weekly activity both in
male and female subjects.
The policy implications are that we cannot expect formal programs to provide sufficient activity of most young people.
Therefore it can also be suggested the recommendations to link
schools and students to community PA programs and to develop effective systems allowing this relationship.
THE RESPONSE TO EXERCISE: FROM GREGOR MENDEL TO
ODED BAR-OR
Bouchard Claude
Human Genomics Laboratory; Pennington Biomedical Research Center,
Baton Rouge, LA, USA
This paper summarizes the content of a lecture presented at the
22nd Pediatric Work Physiology Meeting to honor Professor
Oded Bar-Or on the occasion of his retirement from the faculty
at McMaster University, Ontario, Canada. Gregor Mendel
(1822-1884) published a landmark paper in 1866 based on
crosses between plants. He defined a set of rules that eventually became known as the three Mendel Laws of Genetics. These
principles did not influence the science and practice of medicine for a long time. However, they were proven later to be
fundamental laws of biology and genetics with wide ranging
revista
19.9.03
0:49
Página 27
Invited speakers
implications for contemporary modern biology and human
genetics. More recently, in the last 20 years or so, we have discovered that these laws of genetics also have implications for
the response to exercise and for fitness-related phenotypes.
This is where the contributions of Professor Oded Bar-Or
become highly relevant. Oded was one of a handful of physicians and exercise scientists who focused on children and adolescents, beginning in the 1960s. His training in medicine,
pediatrics and physiology allowed him to ask questions and
pursue research problems that had not been much addressed
before him in pediatric exercise physiology. Some of these
research questions, particularly those pertaining to exercise
physiology and thermal physiology, are quite relevant to the
paradigms of contemporary molecular biology and genetics. It
is a pleasure for me to dedicate this lecture to Professor Bar-Or.
Importance of exercise in children
Regular exercise is known to have beneficial effects on health.
Based on a large number of studies, the evidence is quite
strong that regular exercise is associated with a more favorable
risk profile for common chronic diseases, reduced morbidity,
and lower death rates. A vivid illustration of this phenomenon
is provided by a report of the Centers for Disease Control and
Prevention (CDC) in the USA, estimating that about 300,000
premature deaths per year can be attributed to a sedentary
lifestyle and poor nutritional habits. Moreover, regular exercise
in the form of exercise training increases physical performance.
For instance, endurance training sustained for months and
years can dramatically improve endurance performance in children and adults. Health-related fitness and performance-related
fitness traits have in common the fact that they are complex
multifactorial phenotypes whose heterogeneity in any population of children and adolescents depends upon lifestyle, environmental and social conditions, as well as genetic differences.
Physical inactivity and obesity are known to be quite prevalent
not only in adults but also in children and adolescents of
industrialized countries. When both coexist in a child, pernicious effects are predicted. Excess storage of fat in the form of
triglycerides is known to lead to fat deposition in non-adipose
tissues and organs, a phenomenon known as ectopic fat deposition. Fat infiltration in skeletal muscle, pancreas, and heart
has deleterious consequences on metabolism that have been
defined as being “lipotoxic” (1). A sedentary life style is likely
to increase the severity of the lipotoxic effects of ectopic fat
deposition in children and adolescents. Indeed, exercise is one
of the most efficient modalities known to increase lipid oxidation and thereby reduce the burden of positive energy balance
and excess lipids available for storage.
Even though there is as of yet no direct proof that ectopic fat
deposition has deleterious effects in children and adolescents,
it is likely to be the case. The growing prevalence of type 2
diabetes mellitus in obese adolescents is compatible with the
hypothesis that excessive fat infiltration in non-adipose tissue
reduces insulin action in skeletal muscle and curtail the ability
of the pancreas to meet the demands for insulin in these
youths. Whether there is a genetic predisposition for ectopic
fat deposition is unknown at this time.
Here we are reviewing some of the evidence for a role of
human genetic variation on health and performance traits that
are influenced by regular exercise with an emphasis on children
and adolescents. Three main questions are considered: Are
genetic differences contributing to variation among sedentary
people? Are genetic differences involved in accounting for the
heterogeneity in the response to regular exercise? What do we
know about specific genes, DNA sequence variants and candidate chromosomal regions?
Genes and health-related fitness in sedentary youths
What is the evidence that genetic variation plays a role in
blood pressure, blood lipids and lipoproteins, glucose and
insulin metabolism, adipose tissue and skeletal muscle morphological and metabolic properties, brain and peripheral regulation of food intake and metabolic rates, stroke volume and
cardiac output, VO2 max, and many other health and performance related traits among sedentary people? A large number of
family and twin studies have considered the issue of the presence or the absence of familial and genetic effects. By and
large, these studies have concluded that a significant familial
aggregation is observed for any of the health and performance
traits of interest here. When a genetic hypothesis for the intergeneration transmission could be tested, it typically yielded significant genetic heritabilities ranging from about 20% (e.g.
resting blood pressure, fasting insulin) to about 50 to 60%
(HDL-cholesterol, lean body mass, % Type I fibers in muscle)
for phenotypes adjusted for age, sex and often other concomitants (2). Interestingly, there is some evidence to the effect
that the level of physical activity is also partly inherited. For
instance, twin studies have revealed significant genetic component to the level of habitual physical activity or sedentarism.
Familial studies have indicated significant familial aggregation
for participation in physical activity or for sedentary behavior.
Recently, we were able to complete a genome-wide scan for
physical activity and inactivity phenotypes using the Quebec
Family Study cohort (3). Three highly suggestive linkages were
uncovered with physical inactivity as a phenotype, on chromosomes 2, 7 and 20. The most convincing result was for a QTL
on chromosome 2. A positional cloning effort is currently
underway with the goal of identifying the gene and mutation
responsible for this sedentary behavior QTL. In another series
of studies, we have been able to show that a genetic marker in
exon 6 of the dopamine receptor 2 (DRD2) was associated
with physical activity level in the women of Quebec Family
Study and HERITAGE Family Study cohorts (4).
Individual differences in response to regular exercise
One important question pertains to the heterogeneity in the
responsiveness to regular exercise. We now have solid evidence
that there are considerable individual differences in the capacity to adapt to an exercise-training program. For instance, after
exposure to a laboratory-based standardized program lasting 20
weeks, in which compliance was not an issue for more than
700 participants ranging in age from 17 to 65 years, we
observed that a good number of subjects did not register an
increase in VO2 max, stroke volume, HDL-cholesterol, and
other health and performance-related traits while others registered very significant gains (5). Age, sex, baseline level and
ethnic background accounted for 10% or less of the variation in
response for cardiorespiratory endurance. The main determinant of the individual differences in trainability was the familial background. Indeed, familial aggregation accounted for
about 50% of the variance in the training response, thus
strongly suggesting that genetic factors played a key role in the
ability to benefit from a physically active lifestyle or the capacity to attain very high levels of endurance performance. All
27
revista
19.9.03
0:49
Página 28
Invited speakers
health-related fitness phenotypes investigated thus far in the
HERITAGE Family Study exhibit the same pattern: individual
differences in response to regular exercise but significant familial aggregation of the response pattern.
About the genes involved
The third question has to do with the identification of the
genes and mutations responsible for these apparent genetic
effects. The task is extraordinary complex. The genetic dissection of multifactorial traits requires a variety of strategies
based on in vitro technologies, animal models and human studies. Breeding experiments selecting for endurance performance
in rats have generated high and low lines in which cardiac
properties were strong determinants of performance. Gene
expression studies with cardiac and skeletal muscles are yielding candidate genes that will be subjected to detailed sequence
analysis. Crossbreeding experiments with inbred strains can
also be used to identify chromosomal regions (known as quantitative trait loci or QTLs) harboring genes contributing to the
phenotype of interest. Candidate genes and genome-wide scans
together with expression studies in skeletal muscle or adipose
tissue are the most common strategies currently used with
human subjects. Comparisons of allelic differences between
cases (e.g. people exercising regularly or elite athletes) and
controls (e.g. sedentary individuals or subjects known to be
low responders) can also provide useful information. Genomic
scans performed with hundreds of DNA markers on the HERITAGE Family Study cohort have generated several QTLs for
the response to regular exercise of VO2 max, stroke volume,
exercise blood pressure, body composition, insulin sensitivity,
and other phenotypes. Positional cloning of some of these
QTLs and candidate gene explorations has produced evidence
for a role of DNA sequence variation in muscle creatine kinase,
nitric oxide synthase 3, titin and other genes. The human gene
map for the phenotypes of interest is updated every year by our
laboratory in Medicine & Science in Sports & Exercise (6).
We may be able one day to identify at the DNA level those
who are likely to benefit more from a physically active lifestyle
in terms of health outcomes or to be highly trainable in terms
of cardiorespiratory endurance and other types of physical
attributes. If shown to be true, such advances would have
practical applications for education, youth sports, pediatrics
and preventive medicine.
References
1. Unger, H. and L. Orci (2001). Diseases of liporegulation: new perspective on obesity and related disorders. FASEB J. 15:312-321
2. Bouchard C, R.M. Malina, L. Pérusse (Ed) (1997). Genetics of
Fitness and Physical Performance. Champaign, IL: Human Kinetics
Publishers
3. Simonen, R. L., T. Rankinen, L. Perusse, et al. (2003). Genomewide linkage scan for physical activity levels in the Quebec Family
Study. Med. Sci. Sports Exerc. (in press)
4. Simonen R. L., T. Rankinen, L. Perusse, et al. (2003). A dopamine
D2 receptor gene polymorphism and physical activity in two family
studies. Physiol. Behav. 78: 751-757,
5. Bouchard, C. and T. Rankinen (2001). Individual differences in
response to regular physical activity. Med. Sci. Sports Exerc. 33:6,
(Suppl) S446-51
6. Rankinen T., L. Perusse, R. Rauramaa, et al. (2002). The human
gene map for performance and health-related fitness phenotypes: the
2001 update. Med. Sci. Sports Exerc., 34, No. 8: 1219-1233
28
revista
19.9.03
0:49
Página 29
AUXOLOGICAL AND EPIDEMIOLOGICAL
ASPECTS OF YOUNG ATHLETES
revista
19.9.03
0:49
Página 30
revista
19.9.03
0:49
Página 31
SOMATIC GROWTH IN MAPUTO SCHOOL POPULATION:
TRENDS AND BIO-SOCIAL MEANINGS
Yung Tony, Brown Richard, Green David, Burgess Darren,
Peat Jennifer, Frost Stephen, Searl John
Prista António1, Maia José AR2, Saranga Sílvio1,
Marques António2, Lopes Victor3, Beunen Gaston4
Children’s Hospital, Westmead and Australian Catholic University,
Australia
1 Faculty of Physical Education and Sport Sciences, Universidade
Pedagógica de Maputo, Mozambique
2 Faculty of Sport Sciences and physical Education, University of Porto,
Portugal
3 School of Education, Polytechnic Institute of Bragança, Portugal
4 Department of Sport and Movement Sciences, Faculty of Physical
Education and Physiotherapy, K.U.Leuven, Leuven, Belgium
Keywords: injury, performance, rugby
Keywords: somatic growth, africa, socio economic status
A cross sectional study with a sample of 2271 Mozambican
school aged subjects (1098 boys, and 1173 girls; age 6 to 17)
has been carried out in 1999. The study aimed (1) to contrast
the somatic growth of this population with WHO norms, (2)
to study the influence of socio-economic status, and (3) to verify the influence of dramatic changes in economic conditions
in their growth status, comparing times of war and time of
peace in an African country. Information available concerns
height, weight, skinfolds (triceps and subscapular), and body
mass index (BMI). Subjects were divided in three groups
according to their socio-economic status: low, average, high.
Analysis included descriptive statistics and Ancova (covariate=age). In order to compare times of war and time of peace a
study done in 1992 at the some schools were used as baseline
information (i.e. war time).
Results shows a clear demarcation of percentiles 10, 50 and 90
of height by age and weight by age with those of the WHO,
particularly after age 11 in boys and 12 in girls. Maputo students are always shorter and weight less the norms proposed
by WHO. In boys, BMI is also somewhat lower than WHO
norms, but in girls mean values approach percentile 50.
Privilege boys are significant taller, heavier and fatter than
those from middle and low class. Girls follow similar profile
exept for body fat since middle class girls shown the some values as those from high class. Height, weight, BMI, fat mass,
and lean body mass were always higher in 1999 sample comparing with values from 1992 study.
In conclusion: (1) there is a substantial difference in height
and weight values of Maputo students regarding WHO norms;
(2) it is evident a clear advantage of being of higher socio-economic status; (3) socio-economic, hygienic and sanitary factors
are the responsible agents for the greater values of 1999 sample; (4) differences concerning stature of students with higher
socio-economic status and the WHO norms are almost irrelevant. This last aspect reveals the importance of socio-economic
status in the assessment and evaluation of the growth process,
implying its importance in facilitating the expression of the
genotypes available in the population.
Increasing popularity of Rugby Union among adolescents
resulted in the Australian Rugby Union investigating factors to
describe best practice within talented youth. A multi-disciplinary research project was conducted during the week of the
national championships in 2002.
Players representing the full-back, hooker, lock, half-back, and
5/8 from 12 teams across Australia provided anthropometric,
nutrition and psychosocial profiles, as well as pre and post
game measures of body mass, lactate, repeated sprint speeds
and ratings of leg soreness. Players were further divided into
Division One, in which players were mainly from well-populated and traditional rugby union states and Division Two, in
which the players were from smaller states and representative
squads. Severity ratings of injuries in the two years before the
championships and during the championship week were also
collected. Following tests for normality, the between-Divisions
comparisons were assessed using Fisher’s exact tests and independent sample T tests.
No differences were reported in the majority of variables
including anthropometry, psychosocial measures, relative carbohydrate intake, body weight changes before and after games,
and injury severity during the week. When compared with
Division Two players, Division One players demonstrated
greater changes in lactate during the game (3.0 mM vs 0.9 mM,
P = 0.01), and ratings of leg soreness following the game (P =
0.048). Eighty-two percent of Division One and 43% of
Division Two players reported injuries incurring two or more
weeks of lost games in the two years prior to the tournament
(P= 0.055). Division One players rated higher than Division
Two players on a psychosocial measure of freedom from worry
(P= 0.054).
Results indicate that markers of playing intensity may best discriminate between the divisions and provide benchmarks for
aspiring youth who have a goal of long-term excellence in the
sport of rugby union.
ADAPTATIVE EFFECTS OF DIFFERENT STRENGTH TRAINING PROGRAMS (STRENGTH AND/OR PLYOMETRIC TRAINING):
COMPARATIVE STUDY OF JUNIOR FEMALE VOLLEYBALL PLAYERS
Carvalho Carlos, Cabo Zita, Vieira Luísa, Roriz Paulo,
Carvalho Alberto
Human Movement Laboratory, Higher Education Institute of Maia,
Maia, Portugal
Keywords: strength, plyometric, female junior volleyball
A MULTI-DISCIPLINARY STUDY ASSESSING THE PERFORMANCE
OF JUNIOR (UNDER-16) RUGBY UNION PLAYERS OVER A WEEK
LONG NATIONAL CHAMPIONSHIP
Naughton Geraldine, Burke Stephen, Lee Anthea, Carlson John,
Introduction
Muscular strength in most sports is a determinant factor for
performance. This is especially evident in volleyball. This sport
has gradually come to demand players, who are taller, stronger
31
revista
19.9.03
0:49
Página 32
and more agile in order to satisfy greater physical demands
during a game. Moras (2000) considers strength an important
motor capacity for the performance of volleyball players. The
American Volleyball Coaches Association (1997) states that
strength training (ST) is obligatory in order to optimise a volleyball player’s performance.
Vargas (1982) mentions that the majority of volleyball movements occur on the basis of greater strength velocity.exercises
Examples of this are: quick start, change of direction, sudden
stops, jumps, along with rapid movements of upper body and
limbs whenever a player does blocking, serving and striking.
Blume (1989) also agrees on the importance of explosive strength
and states that rapid attack and defense movements suggest a
solid development when force is involved. Therefore, strength in
its multiple aspects: rapid, explosive and reactive strength is
extremely important in the volleyball (Carvalho, 1998).
Authors such as Weineck (1986) and Saraiva (2000) say that
obtaining high levels of sport performance becomes more and
more difficult when there is inadequate training and development of strength in children and adolescents. Saraiva (2000) also
talks about the importance of strength training in female teams
due to their natural physical “fragility” in comparison to the
opposite sex. Thus, we believe that working with junior athletes,
in particular females, in order be familiar with the effect of a
strength training initialising before any type of sport activity.
In relation to the quality and orientation of ST among young
athletes a balanced and multilateral strength training program
is recommended so that there is greater fitness, better sports
performance and a higher prevention of injuries. On the one
hand, much literature focuses on the importance of plyometric
training in Volleyball because of high levels of rapid strength in
stretch-shortening cycle (SSC).
Pyometric is a method which combines strength and speed; it
is a capacity of the most rapid speed possible (Cossenza,
1995). Plyometric refers to many types of jumps, such as: hopping on one or both feet, vertical, horizontal and combined
jumps, jumping on and over objects, jumping from high to low
levels without bounce.
The main aims of the present study were not only to verify the
adaptative effects of different strength training programs
(strength and/or plyometric training) but also to confirm
which of the two is more adequate in improving different types
of strength and speed.
Methodology
The sample involved 17 female volleyball players at a junior
level with the same competitive abilities. The sample was
divided into two distinct experimental groups: one training
program corresponded to common strength and plyometric
exercises (mixed training) for lower limbs (CMGC team,
n=10); the other program corresponded to plyometric exercises for the lower and upper limbs (AASM team, n=8). The
training lasted ten weeks.
Assessment took place before and after each training program
and involved the following parameters: anthropometric measurements, maximum isometric strength (knee extension 90º)
dynamic strength (pull-over and leg press) power, explosive
and reactive strength (SJ, CMJ, CMJ-bl, CMJ-stk, DJ 40cm and
PMM-15”) and speed (zig-zag and Japanese).
32
Table 1 – Evalution tests of maximum isometric and dynamic strength,
of explosive and reactive strength and of speed
Training Programs
The program of resistance training was applied only to the
CMGC. The load was: 2 series of 12 to 15 repetitions, with an
interval of 120” between series. The load was always increased
when athletes could do more than 15 repetitions easily. The
exercises were: bench press; lat pull-down; leg press; knee flexion; pull-over; knee extension; bicep curls; rowing; calf raises;
abdominals; back extension.
The plyometrics training program for both teams involved,
load: 2 series of 15 repetitions and 30” interval between exercises and 1’30” between series. Exercises: (i) going up and
down a step as quickly as possible; (ii) side to side jumps over
a bench; (iii) double leg speed hop; (iv) knee tuck jump; (v)
depth jump; (vi) jump from a box/step followed by vertical
bounce; (vii) one legged hop; (viii) squat jump.
This plyometric training program was done by AASM. A warm
up of 15’ which included multiple types of jump like: skips, ricochets, hops, bounds, leaps and lunges. Exercises: (all exercises were performed in pairs and with medicines balls) (i) chest
pass; (ii) throwing over head throw; (ii) one handed pass
(alternating); (iii) chest pass with leg extension; (iv) scoop
toss; (v) sit-up throw; (vi) throwing with legs a part and back
to back lateral throw.
Statistical procedures
For all the variables we calculated the mean and deviation pattern. In each group and in two study periods, we carried out
the T-test for repeated measures. The analysis of change within
each type of strength training program was done in the following mode: (i) regression analysis of the values compared with
the initial values; (ii) one-factor analysis of variance to test the
differences in the performance of the groups considered; (iii)
multiple comparison procedure a posteriore carried out with the
Scheffé test when the F-value was significant. The level of significance was maintained at 0.05. The analysis of the data was
done through the use of the statistical program Statview 2.0.
Results and discussion
Isometric and dynamic strength
One can see from Table 2, in relation to the knee extension test
and the pullover and leg press, that the groups registered
improvement. But it was only in the pullover that significant
statistical differences occurred in both groups.
revista
19.9.03
0:49
Página 33
Table 2 – Maximum isometric and dynamic strength in each group
[mean (x), standard deviation (Sd), absolute (Abs) and percent (%)
gains, t and p values, during both moments of assessment.
* Significant statistical differences (p ≤ 0,05)
The AASM team showed significant statistical gains in relation
to the maximum strength. However, neither one of the training
programs showed relevant changes within the group.
Explosive and reactive strength
Table 3 and Figure 1 show results of the vertical jump tests
which assessed explosive and reactive strength (long and
short) of the upper limbs. The results confirmed that the
AASM group had gains in the following tests SJ, CMJ, CMJ-bl,
CMJ-rt and DJ40 but with a decrease in the PMM. However,
there were significant statistical changes in CMJ. The CMGC
team had gains in the CMJ-bl, CMJ-rt and PMM, and less in the
SJ, CMJ e DJ40 all with no statistical significance. This results
are abnormal and difficult to explain.
Table 3 – Explosive and reactive strength in each groups [mean (x),
standart deviation (Sd), absolute (Abs) and percent (%) gains, t and p
values, at both moments of assessment].
Figure 1 – Comparison of the mean values (cm) of explosive and
reactiva strength for the lower limbs (SJ, CMJ, CMJ-bl, CMJ-stk,
DJ40 and PMM), in each group (CMGC vs AASM team)
during both moment of assessment.
When comparing both groups, the CMGC team had lower
results in all the tests before beginning the training programs.
The analysis of variance (ANOVA), the regression of the final
values from the initial ones showed significant differences
between the CMGC and the AASM in the CMJ test, which
indicates that the program that AASM underwent was more
demanding in order to obtain better gains.
Speed
The study which took place was registered in two tests: Zig-zag
and Japanese tests.
When analysing Table 4, one can verify that the AASM team
managed to conclude both tests in less time, contrary to what
happened to the CMGC team. There are differences which have
relevant statistical differences in the Japanese test, these differences do not relate to improved performance but to bad results
obtained by the CMGC.
Table 4 –Speed in each groups [mean (x), standart deviation (Sd),
absolute (Abs) and percent (%) gains, t and p values,
at both moments of assessment].
* Significant statistical differences (p £ 0,05)
Conclusions
This analysis permitted us to come to the following conclusion:
Both training programs had gains in maximum isometric and
dynamic strength but the plyometric training group predominated, because it had significant statistical gains in two tests
and the mixed training group only had gains in the pullover. In
relation to explosive and reactive strength, only the plyometric
training program had gains of a statistical importance and it
was also here that greater gains occurred in speed displacement.
Although, the plyometric program showed greater gains, the
range of improvement was not satisfactory in order to differentiate the two groups. Therefore one can not conclude the accuracy of either training programs.
33
revista
19.9.03
0:49
Página 34
References
American Volleyball Coaches Association (1997). Coaching Volleyball.
In Kinda S. Asher. Chicago. Masters Press,
Blume, G. (1989): Voleibol. Édiciones Martinez Roco, S.A. Barcelona
Carvalho, C. (1998): O desenvolvimento da força nas crianças e jovens
a sua treinabilidade. Treino desportivo. Edição do CEFD. Ano I, 3ª
série, pp 29-36.
Cossenza C. (1995): Musculação. Sprint. Rio de Janeiro.
Moras, G. (2000): La preparación integral en el Voleibol – 1000
Ejercícios y Juegos. Volume I. Colección Deporte – 2ª Edição. Editorial
Paidotribo. Barcelona
Saraiva, L. (2000): Efeitos múltiplos e multilaterais de um plano de
treino de força geral no desenvolvimento das diferentes expressões de
força - um estudo em voleibolistas juvenis do sexo feminino.
Dissertação de Mestrado. FCDEF - UP.
Vargas, R. (1982): La preparación Física en Volleyball. Editorial
Augusto E. Pila Teleña. Madrid.
Weineck, J. (1989): Manual de treinamento esportivo. 2ª edição.
Editora Manole Ltda. Brasil.
of training in Basketball. The training programs were applied in
the end of the regular training sessions, during 8 weeks with a
tri-weekly regularity. The GExp1 carried through 20 minutes of
continuous race; the GExp2 fulfilled a circuit training program
that included 4 techcnical-tactical exercises applied at 4 differentiated moments (each exercise was applied during 2 weeks,
with the following load dynamics: 3 series of 4 minutes each
with 1 minute interval between series). The player’s general
endurance was evaluated in a pre post-test model using as criteria method the distance covered in the Cooper Test
(Kirkendall et al., 1987).
Statistical analysis included Mann-Whitney U test for intergroups comparisons and Wilcoxon test for intra-groups
comparisons.
Results and discussion
Table 1 presents differences from pre to pos test in the two
groups studied.
Table 1. Results of mean comparison between
pre and pos test in Gexp1 and Gexp2.
COMPLEX TRAINING VS. ANALYTICAL TRAINING: EFFECTS ON
GENERAL ENDURANCE OF YOUTH BASKETBALL PLAYERS
Janeira Manuel1, Novais Bruno1, Brandão Eurico1,
Sampaio Jaime2
1
2
Faculty of Sports Science, University of Porto, Portugal
University of Trás-os-Montes e Alto Douro, Portugal
Keywords: complex training, general endurance, basketball
Introduction
Teaching Basketball is a slow process that requires a strong
investment from coaches and players.
Methodological orientations for young athletes sport preparation suggest the importance of aerobic exercise (Bompa, 2000;
Basketball Canadá, 1987; Janeira, 2001).
Traditionally, continuous race is the most used method to
endurance development, habitually accomplished in an analytical context.
Recently, some authors have been criticizing this training
process (away from game context) and they have been promoting a different training type designated by Complex Training,
accomplished from tactical exercises and game structures with
multiple repercussions in the different components of the athletes’ physical fitness (Chirosa Rios et al., 1998; Janeira, 2001;
Vaquera, 2001). Complex Training is highly motivator for athletes (requesting exercises always accomplished with ball) and
also contains a strong idea of time economy (Lozano, 2001;
Janeira, 2001).
In spite of arguments promoting Complex Training, is still
unknown its effectiveness in young Basketball players preparation.
The aim of this study was the following: (i) to evaluate the
effect of the Complex Training and the Analytical Training in
general endurance of youth Basketball players.
Methods
The sample comprises 10 athletes all from the same male team
(age=11,80±0,87 years), random splited in 2 groups (GExp1,
GExp2). All players were submitted to the same specific type
34
Main results revealed significant differences between pre and
post-test in the two groups studied (GExp1: +126,61±79,11
meters, p=0,023; GExp2: +105,26±36,99 meters, p=0,003).
However it is clear a similarity between pre and pos test.
(Table 2.) In fact, relative profits between pre and pos test were
the following: GExp1=5,73% and GExp2= 5,48%.
Table 2 presents the absolute and average profits between pre
and pos test in the two groups studied.
Table 2. Average profits (absolute and relative)
between pre to pos test in Gexp1 and GExp2.
Values are average ± standard deviation
(*) Statistical differences between pre and pos test.
The largest profits identified in GExp1 relatively to GExp2 can
be probably attributed to the obvious similarities between continuous race training and the evaluation test used. However,
Complex Training differs just 0,25%. From our point of view
this value is irrelevant and expresses the idea of quality in
technical, tactical and physical conditioning training designed
to implement the aerobic capacity of the youths Basketball
players. In other words, the Complex Training proposed, based
upon exercises usually used in Basketball practices and tactical
structures designed from team’s game model, were able
enough to develop athletes' aerobic capacity levels, at least to
similar values reached through continuous race training.
These results confirm "youth training process should be drawn
in a very strong approach to Basketball from a economic training perspective" (Janeira, 2001; pp. 31). The author also refers
that the advantages of this training method are multiple with
revista
19.9.03
0:49
Página 35
main relevance on: (i) the mobilization of the more used muscular groups, and (ii) the simultaneous development of technique, tactics and physical conditioning in similar conditions to
the competition. On the other hand, this training method
seems to be highly profitable facing the limited available time
for the youth athletes' training process and it is also attractive
and motivator.
In fact, with the Complex Training it seems possible to promote a multiple sport preparation with high-level athletes'
effort and with a strong time economy.
Training programs supplied in GExp2 provided a significant
increase in the distance from the first to the second evaluation
moment. This increment of the aerobic capacity express by the
high distance travelled in the second evaluation was obtained
by a work volume of about twenty minutes, distributed in four
series, with one minute interval between them. This fact
allowed a continuous effort, mobilizing the more requested
muscular groups in Basketball and an execution intensity that
allowed us to identify each athlete's breathing frequency. This
methodological training organization allows us to establish
that the more close the situations proposed are from the game
reality, faster and better will be the motor transfer and the promotion of Complex Training as an effective training process.
In conclusion, the Complex Training showed a similar power to
the Analytical Training in the modification of the general
endurance of youth Basketball players.
References
Basketball Canada (1987). Level 1 Technical. Canada: National
Coaching Association of Canada.
Bompa, T. O. (2000). Total Training for Young Champions
Chirosa Ríos, L. J.; Chirosa Ríos, I.; Puche, P. P. (1998). [On-line]:
www.efdeportes.com/efd11a/bnm.htm
Janeira, M. A. (2001). Treino Desportivo-Especial (4): 30-32.
Kirkendall, D. R.; Gruber, J. J.; Johnson, R. E. (1987). Measurement
and Evaluation for Physical Educators.
Lozano, D. O. (2001). [On-line]: www.efdeportes.com/efd41/infl.htm
Vaquera, A. (2001). Clinic,(55): 29-32.
players competed in the 2002 season. The first and second test
session was conducted at the beginning and final of preparation period to the season (in March and June) and the third
test session at the final of competitive period (November). The
battery of tests included measurements of body mass (kg),
heigth (cm), sum of 2 skinfolds (triceps and subscapula)
(mm), Yo-Yo Intermittent recovery test (m) to assess the ability to recover after intense exercise (Bangsbo, 1996), a 30-m
sprint (s), a Quebec 10s test to assess anaerobic power (W/kg)
and capacity (J/kg) (Simoneau, Lortie, Boulay, Bouchard,
1983). The assessment conditions were similar (surface, hour,
temperature) in all tests. For data analysis we used the procedures to descripitive statistics (mean, standard deviation), the
one-way ANOVA for testing the mean differences between the
age group. A criterion alpha level of p<0.05 was used and
Duncan post hoc comparisons were used to distinguish
between the groups.
The U17 athletes and U19 had significantly greater mean body
mass, in the first test session, and Yo-Yo intermittent recovery
test, in all test sessions, and a significantly lower time 30-m
sprint, in the first and second test sessions, than U15. The U19
athletes had significantly greater mean Yo-Yo intermittente
recovery test, in all test sessions, and a significantly lower time
30-m sprint, in the first and second test sessions, than U17.
The results of this study suggest that the main differences
between age groups during the season is in the ability to recover after intense exercise and speed.
SOMATOTYPE AND PHYSICAL PERFORMANCE
IN YOUNG FEMALE VOLLEYBALL PLAYERS
Garganta Rui, Seabra André, Maia José AR, Pereira Simonete,
Silva Domingos
Faculty of Sports Science and Physical Education,
University of Porto, Portugal
Keywords: somatotype, physical performance, young female, volleyball
PHYSIOLOGICAL AND ANTHROPOMETRIC DIFFERENCES
BETWEEN AGE GROUPS OF YOUNG BRAZILIAN
SOCCER PLAYERS DURING THE SEASON
Silva Neto Leonardo, Nunes Cristiano G, Hespanhol Jefferson E,
Goulart Luis F, Arruda Manuel
UNICAMP, Brasil
Keywords: soccer, exercise, physiology, anthropometry
Success in soccer is dependent upon a variety of factors. These
include the physiological and anthropometic characteristics of
the players, their level of skill and their psychological profile.
The aim of this study was to examine the differences in physiological and anthropometric characteristics between age groups,
obtained in three separated stages during the season (March,
June and November), in young male soccer players.
The subjects were 70 males brazilian soccer players between
the ages of 14 and 18 years.The players group was divided into
age group: U15 (n= 20), U17 (n= 36) and U19 (n= 14). All
The purpose of this study was to evaluate the magnitude and
relevance of the relationship between somatotype and physical
performance of young female volleyball players.
Subjects for this study were 179 young female volleyball players
aged 15.28±1.38 (12.00 to 17.90) years old. Somatotype was
assessed with the Heath-Carter method for determination of
Endomorphy, Mesomorphy and Ectomorphy. Physical performance was evaluated with the following tests: 18 m Run, Shutle
Run (48 m) Static jump (SEM), Counter Movement Jump
(SCM). These tests were done according to Bosco protocol.
Statistical analysis included not only basic stats, but also
canonical correlation (Rc) which uses Chi2 as test statistic for
the significance of Rc, and Stuart-Love canonical redundancy
index (SLri) as a mesure of multivariate variance-covariance
extrated by somatotype of physical performance domain. All
analysis were done in Systat 10.
Somatotype and physical performance variables showed high
reliability estimates (R>0.80). Voleiball players were classified
as mesomorphic-endomorph (4.68 - 3.84 - 2.32).
Only one canonical correlation was found significant and was
low value, Rc=0.40, χ2(12) =33.304, p=0.001; common vari-
35
revista
19.9.03
0:49
Página 36
ance-covariance was Rc2=17.4%. Canonical loadings in each
domain (somatotype and physical performance) showed a high
value for endomorphy (0.95) and negative values for physical
fitness (18 m run =- 0.68; SEM = -0.96; SCM = -0.81).
Conclusions: (1) somatotype as a whole explains little generalized variance-covariance of the physical performance of young
female volleyball players; (2) endomorphy is highly responsible
for this characteristics because it was negatively related to performance in running speed and explosive strength. These
aspects call for a more in depth approach of the relationship
between some somatic variables (not shape variables) and the
motor domain of young volleyball players.
PHYSICAL STRUCTURE AND AEROBIC/ANAEROBIC FITNESS OF
ADOLESCENT HOCKEY PLAYERS AND LINE-SKATE RUNNERS
WITH A SPECIAL REGARD ON SPECIALIZATION AND ELITISM
Coelho e Silva Manuel, Massart Alain, Santos Amândio,
Vaz Vasco, Ferrão Nuno, Amendoeira Patrícia,
Figueiredo António, Sobral Francisco, Malina Robert
University of Coimbra, Portugal
Keywords: physical structure, aerobic/anaerobic fitness , sport selection
The present study summarizes the morphological and physiological information of line-skaters and hockey players taking
into account their level of competition. This information would
be relevant to support decision making on sport specialization
and sport selection during adolescent years.
The sample is composed of 20 line-skaters of the Portuguese
national team and 51 male hockey players (41 local athletes, 10
participants in the 2002 European Championship). Data collection comprised anthropometric information needed to determine body size, fat body mass (Boileau et al., 1985), androgyny
(Tanner et al., 1951) and somatotype (Carter & Heath, 1990),
while fitness were assessed as aerobic capacity (PACER) and
anaerobic peak power (Wingate test).
Comparisons between sports showed that line-skaters and
hockey players have similar body size. However, the formers
are more androgynous (p<.05). Hockey players tend to be
slightly fatter and attain better performance in aerobic test and
poorer results in anaerobic parameters.
Comparisons of hockey players by competitive level show that
athletes selected for national team are heavier (p<.01), leaner
(p<.01) and more androgynous (p<.01). Data regarding physiological profile showed that top players are fitter in both aerobic (p<.01) and anaerobic fitness (p<.01). After controlling for
differences in body size, youth elite hockey players and lineskaters seem to have similar anaerobic profile than older team
sport players reported by Kalinski et al. (2002).
References
Carter J, Heath B (1990). Somatotyping - development and
applications.
Kalinski MI, Norkowski H, Kerner M, Tkaczuk WG (2002). Eur J Sp
Sc. Vol. 2 (3)
Tanner JM, Lond MB, Penna MD (1951). The Lancet. 1: 574-579
MODELING STABILITY OF SOMATOTYPE.
A STUDY IN BOYS AND GIRLS FROM
THE AUTONOMOUS REGION OF MADEIRA (PORTUGAL)
Silva Celso1, Maia José AR2, Freitas Duarte3, Beunen Gaston4,
Lefevre Johan4, Claessens Albrecht4, Marques António2,
Rodrigues António1, Crespo Maria5, Thomis Martine4
1
Centro Hospitalar do Funchal, Funchal, Portugal
Faculty of Sport Sciences and Physical Education, University of
Porto, Porto, Portugal
3 Department of Physical education and Sports, University of Madeira,
Funchal, Portugal
4 Faculty of Physical Education and Physiotherapy, K.U.Leuven,
Leuven, Belgium
5 INE, Portugal
2
Keywords: modeling, stability, somatotype
This study aims at the search of somatotype stability and predictors of interindividual changes (sports participation and
skeletal maturation).
A sample of 99 boys and girls from the Autonomous Region of
Madeira (Portugal) were followed longitudinally for three years
(mean ages of 11.73; 12.70; 13.73). Somatotype was rated
according to the Heath-Carter methodology. Sports index was
evaluated with the Baecke et al. (1982) questionnaire. Skeletal
age was assessed using the Tanner-Whitehouse Mark II system.
Stability of somatotype and predictors of change were modeled
with a quasi-simplex covariance structure within the Mplus
(Muthén and Muthén, 2001) software framework.
Reliability estimates for somatic measurements (R>0.87),
response to questionnaires (R>0.73) and skeletal rating (%
Agreement >81.3%) were all excellent, giving credit to the
quality of the data available.
Somatotype, as a whole, is highly stable β21= 0.84; β32= 0.96)
with very low residual variances (D21= 0.20; D32=0.20).
Tracking is also very high, r1,2=0.93; r2,3=0.94; r1,3=0.88. No
significant influences were found for sports participation nor
for differences in biological maturation.
In conclusion several points deserve attention: (1) the very
high stability of somatotype over a 3 year period during puberty; (2) somatotype as a whole tracks well from 11.73 to 13.73
years, with a high predictability; (3) sports index does not
influence somatotype plasticity during this period probably due
to the fact sports ratings are stable over this period (
Sp1=2.68; Sp2=2.90; Sp3=2.77); (4) although differences
were found in skeletal age at each period (p1=9.60-15.70;
p2=9.87-15.83; p3=10.96-17.35), mean ages are almost equal
(p1=12.58; p2=12.90; p3=14.14); (5) we think that a greater
sample and a panel study with more measurement periods
would probably change these results and would show the plasticity of physique over the entire puberty within the limits of
genotypic influences.
PHYSIQUE AND BODY COMPOSITION PARAMETERS OF
PREADOLESCENTS
Farkas Anna, Zsidegh Miklós, Tatár András, Prókai András,
Mészáros Zsófia, Uvacsek Martina, Vajda Ildikó
36
revista
19.9.03
0:49
Página 37
Faculty of Physical Education and Sport, Semmelweis University,
Budapest, Hungary
Keywords: physique, body composition, preadolescents
Introduction
By our knowledge it is evidence that there are sex characteristic differences between adults, between females and males. But
what is the case in earlier ages? Those differences would
become obvious by the adolescence and after, but they are not
so marked during the preadolescent age period. The most
marked differences in the two sexes are occurred in body
dimensions, such as body height and weight, in the skeletal
system, as the characteristics of bone mass and density, and in
body composition. The increasing tendency of gaining body fat
in females starts at an early stage of puberty, caused by the sex
specific hormone level increase. The male-specific changes, in
this respect, will cause marked increase in muscle mass all
through the puberty period, and lead to absolute and relative
body fat decrease.
All those sex-specific differences can be summarised by the
well-known phenomenon of sexual dimorphism, that is more
characteristic in adulthood, but also have some signals before
the so obvious changes in the maturation process. Some differences in lean body mass and fat mass in young boys and girls
was reported Faulkner et al. (1993) and Nelson et al. (1997).
Those findings pointed out the differences in body composition
parameters even before puberty, with very similar, mostly no
significant differences in the height and weight mean values.
The essence of those non-significant differences seems to turn
from quantitative to qualitative changes, that leads also to the
difference in measurable and so different gender characteristics.
So when speaking about gender differences we have to be more
precise in monitoring bodily parameters, because it seems that
some detectable differences exist in spite of the very similar
body dimensions. Moreover, not to consider only the statistics
to prove changes but even yet the slight differences should be
taken into account.
Methods
The sample embraced altogether 517 Hungarian elementary
schoolchildren, 244 girls and 273 boys, respectively. Their
chronological age was 9 years. All body measurements were
taken by the guidelines of IBP (Weiner and Lourie 1969), namely: body height, weight, shoulder width, chest width, chest
depth, bi-iliochristal diameter, bicondylar width of the humerus
and the femur, chest circumference, upper arm circumference –
relaxed and contracted, forearm circumference, hand circumference, thigh, calf and wrist circumference, and the skinfold thicknesses, namely: biceps, triceps, supscapular, supra-iliac, abdominal, thigh and medial calf skinfolds were taken. Basic body
measurements, such as body height and weight were taken, and
BMI was calculated, though we know that BMI has its validity
mostly in large samples, and in limited extent in children
(Lohman 1992). Conrad’s growth type indices (1963) were
used to characterise the body proportions and the musculoskeletal development of the body. Metric index refers to body
proportions using chest width, chest depth and body height
parameters, assessed by sex-specific equations. Plastic index
characterises the musculo-skeletal developmental level by the
absolute value of the shoulder width, forearm circumference
and hand circumference measurements. The metric and plastic
indices indicate an individual point in a specific co-ordinate system, with different scaling for the genders, following an age
dependent tendency through childhood and adolescent period.
Somatotype components were used to describe endomorphy
(relative fatness), mesomorphy (relative robustness) and ectomorphy (relative linearity) of the youngsters following the suggestions of Carter and Heath (1990).
Body composition parameters were assessed by Drinkwater and
Ross body fractionation technique (1980) estimating body fat,
bone, muscle and residual absolute and percentage values. In
this study the body-weight-relative means are demonstrated.
Body fat content also was assessed by Parizková’s method
(1961) in percent of the body weight.
Means and standard deviations were calculated and also minimum and maximum values are demonstrated in the tables
(Table 1 and 2). Linear correlation coefficients were calculated
showing age-dependent interrelations between the studied
variables in 9-year-old boys and girls (See Table 5 and 6).
Results
The means, standard deviations and minimum and maximum
values of the studied parameters are demonstrated in Table 1
and 2, for the girls and for the boys, respectively.
In body height and weight no significant differences were
found in the means of the girls and boys. The BMI means also
were the same, to statistically. We can see something very
interesting in the trend of changing the BMI with age. Both in
Hungarian and international reports exists a trend that boys’
BMI mean values exceeded that of the girls in the early childhood, than in preadolescent period girls had higher means, and
only in later adolescent years, by 16 or 17 years boys had again
larger BMI (Lohman 1992, Eiben et al 1998). This phenomenon might be explained – in spite of the generally larger body
size of the boys - by the earlier maturation of the girls, the proportionally larger body mass, due to the more expressed
increase in body fat content (See Table 4).
Somewhat higher mean values for the boys can be seen in plastic index, so their musculo-skeletal developmental level were
higher than that of the girls. After the adolescent period it is
obvious that the males are more developed in that respect. On
the other hand, girls are significantly more linear, characterising them by the metric index.
By the Carter and Heath (1990) somatotype components both
girls and boys belonged to the central area somatotype, though
girls had somewhat higher endomorphy, slightly lower mesomorphy and practically the same ectomorphy component mean
values. Bodzsár (2001) reported on the consequently more
marked endomorphy in girls compared to boys. She also stated,
that gender differences in the characteristics of the physique
became more expressed with age. The rate of the three components suggests the higher adulthood muscularity of the males
and higher relative fatness of the females.
The body fat content was consequently higher for the girls,
irrespectively the method assessed by. This difference, if not
even reached the level of significance, focuses on the future
trend of changes in the two sexes.
There was a standard difference between the two fat estimation
method of Parizková (1961) and Drinkwater and Ross (1980)
technique. By our experiences the Drinkwater and Ross
method slightly overestimates the fat content, and it is not so
sensitive for the changes. By increasing the fat content there
is an increasing tendencybetween the difference of the two
37
revista
19.9.03
0:50
Página 38
method’s assessment. By our opinion Parizková’s method gives
more real results and also follow the changes of the body composition easily. But we also use the Drinkwater and Ross technique, to characterise the other body components.
Table 1: Means, standard deviations,
minimum and maximum values of girls (n=244)
38
The relative residual mass was the same in the two genders,
but the bone percentage value was somewhat higher for the
boys, that could be a signal for the consequently higher adolescent and adulthood average bone mass, both in absolute and in
relative meaning.
In Table 3 we can see the mean values of the different nationwide studies (Mészáros and Mohácsi 1983, Eiben et al. 1991,
Eiben et al. 1998), how body measurements and characteristics
had been changed in the last decades. It can be clearly seen
that recent data exceeded that of the previous studies of the
eighties and the nineties, proving the secular growth changes
in the subsequent generations. It is also interesting that the
Budapest data. There was a standard difference between the
two fat estimation method of Parizková (1961) and Drinkwater
and Ross (1980) technique. By our experiences the Drinkwater
and Ross method slightly overestimates the fat content, and it
is not so sensitive for the changes. By increasing the fat content there is an increasing tendency both height and weight
mean values exceeded that of the nationwide results. The phenomenon that children living in (large) cities have larger body
size compared to children living in the country, in little settlements or villages could be seen and was proved in Hungary in
different age groups (Eiben et al 1998, Farkas et al 1989/90).
The background of it could be explained by the relatively more
frequent external impulses, larger amount of information stimulating the growing and developing organism.
Table 2: Means, standard deviations,
minimum and maximum values of boys (n=273)
Table 4: Comparative data on the BMI reference values
Table 3: Comparative data of basic
anthropometric variables – boys and girls
Considering the results of the linear correlations there were
some differences between the genders. First of all, the chronological age proved to be independent in girls, but it was slightly
related to height, metric index and to the ectomorphy somatotype component. Among the closest relationships we have to
mention both in boys and girls between the body weight and
BMI and the plastic index. Both connections seem evidence
since BMI contain the major factor of body weight. On the
other hand, the plastic index could be in close connection with
the body weight, because both are related to body size, as well.
BMI has a negative connection with the ectomorphy component, so those children being more ectomorph, would have
lower BMI value.
revista
19.9.03
0:50
Página 39
Table 5. Results of linear correlation in girls (n=244)
Where: BH- body height, BW – body weight, BMI – body mass index,
MIX and PLX – metric and plastic indices of Conrad’s growth type,
I,II, III – Heath and Carter somatotype components, F% - body fat
content, estimated by Parizková’s method, FD% - body fat content
estimated by Drinkwater and Ross technique, B% - M% - R% - bone,
muscle and residual percentage values of body fractionation method.
Table 6. Results of linear correlation in boys (n=273)
Abbreviation: CA - chronological age, others see above in Table 5.
The connection between the first (endomorphy) component,
the relative fat content and the body fat, assessed by either the
Parizková’s (1961) or the Drinkwater and Ross (1980) technique would be closely related in both sexes. All those children
having higher muscularity or robustness, characterised by the
mesomorphy component would be less ectomorphic, and “vica
versa”. The other close and reversed relationship, that seemed
evidence, occurred between the body fat and the muscle content, estimated by the Drinkwater and Ross (1980) method.
Discussion
In our present report we described the basic anthropometric
characteristics of the 9-year-old preadolescent children. That age
period is the last phase of the growth process, when the representatives of the two genders are yet similar in their body measurements and the characteristics of the physique, though some
kind of differences we could find even at that early age period.
At that time the two genders do not differ significantly in most
of the bodily parameters, but show some kind of “signals” of
the future sex-dependent dimorphism (Nelson et al. 1997,
Faulkner et al. 1993). Most of those non-significant trend of differences are in close connection with the body composition
parameters, such as body fat content, irrespective of the method
of assessment. On the other hand we have to add, that the fat
content estimated by Parizková’s method (1961) had closer
relations with the studied parameters. In this respect, it seems
to us that using this assessment we could gain more real variable. The somatotype components also contained some possible
directions of changes, such as the more characteristic endomorphy in girls. Bodzsár (2001) found a constantly higher endomorphy existing in girls and she also stated that gender differences would become more obvious by the adolescent period and
later. The trend of changes in somatotype components have
gender characteristics, as girls are becoming more endomorphic
and less ectomorphic during puberty.
All above mentioned findings showed, that no real differences
can be seen in basic body dimensions at the studied age, but
from than on, a gradually accelerating effect of growth, development and maturation would lead to the characteristic gender
differences i.e.: an increasing tendency of BMI in girls up to 16
to 17 years of age. After that age boys would exceed that of the
girl/female mean values. We know as evidence, that body fat
content increase would be more expressed in girls, due to the
hormonal changes, and the same reason would lead to muscle
content increase in boys, later. So the difference could be seen
more in the body composition parameters.
By observing the differences in the studied variables in the
consecutive decades we can also state that secular trend
changes are even existing in basic body dimensions. By the
interrelationships in the studied variables we found very similar connections in the two genders that also strengthened our
experience: the similarity in the developmental phase of the 9year-old children. But at the same time we have to remember
that there are some detectable sex differences before the onset
of puberty, even at the age of 9 years or so, when there are not
yet measurable differences in body dimensions (Kelly et al
1992, Forbes 1987, Nelson et al. 1997, Faulkner et al. 1993).
The higher fat content in females starts accumulate in the early
years and would become sex characteristic evidence by the
puberty and later. In this respect we also have to take into consideration that genders have different activity level that also
contribute to the gradual changes and the more expressed differences between boys and girls, or later, females and males.
References
Bodzsár ÉB (2001) Humanbiologia Budapestiensis, Suppl 28
(in Hungarian)
Carter JEL, Heath BH (1990) Somatotyping. Development and
application. Cambridge University Press, Cambridge
Conrad K (1963). Der konstitutionstypus Springer Verlag, Berlin.
Drinkwater DT, Ross WD (1980). Kinanthropometry II. 178-189
University Park Press Baltimore
Eiben OG et al (1991) Humanbiologia Budapestiensis, 21
Eiben OG et al (1998) Humanbiologia Budapestiensis Suppl 24
(in Hungarian)
Faulkner RA et al (1993). Calcifion Tissue Inter 53:7-12
Farkas A et al (1989/90) Anthropológiai Közlemények, 32: 197-200.
Forbes G (1987). Human body composition Growth aging, nutrition
and activity, Springer Verlag New York
Kelly J et al (1992). J Ped Child Health 28:158-161
Lohman TG (1992) Advances in body composition assessment.
Monograph No3Human Kinetics Publ.
Mészáros J, Mohácsi J(1983). The level of maturation and the prediction of adult hight determined by the developmental process of urban
youth. Candidate Thesis. Hungarian Academy of Science, Budapest
(in Hungarian)
Nelson D et al (1997). Bone 20:73-79
39
revista
19.9.03
0:50
Página 40
Parizková J (1961). Metabolism 10:794-807
Weiner JES Lourie JA (Eds)(1969) Human biology. A Guide to Field
Methods IBP Handbook No 9, Blackwell Oxford
BODY FAT CONTENT AND AEROBIC POWER IN 10-YEAR-OLD BOYS
Mohácsi János1, Petrekanits Máté2, Zsidegh Petra1,
Ihász Ferenc1, Mohácsi Ágnes1, Tatár András1, Prókai András1
1 Semmelweis University Budapest, Faculty of Physical Education and
Sport Sciences, Hungary
2 BHSE HUMET Clinic Budapest, Hungary
Keywords: physical performance, body fat content, sedentary lifestyle
Introduction
The hypothesis that the higher level of cardiorespiratory fitness
provides protection against obesity and also the hazards of obesity does not mean that aerobic power of fat and obese children
and adolescents is consistently lower than that of the lean
ones, however, the lower physical performance - assessed by
various running, jumping and throwing test scores - of fat and
obese children seems to be obvious, and can be attributed to
the joint consequences of high body fat content and sedentary
life style (Bouchard 2000, Frenkl et al. 1988, Othman et al.
2002). Regular physical activity is an important factor in the
regulation of body composition. Although training-associated
changes in fatness are reasonably well-documented in children
and youths, information about the effects of regular training on
adipose tissue cellularity and metabolism in children is lacking.
Relative changes in VO2max per unit body mass associated with
training are remarkable, generally a little trainability of maximal aerobic power is characteristic in children under age 10
(Malina and Bouchard 1991). Since Othman and associates
(2000) published significantly greater peak aerobic power in 910-year-old athletic boys than in non-athletes, it is not certain
whether these results are the consequences of a low adaptive
potential of young children to aerobic training or to the inadequacies of the training program. The selection effect cannot be
excluded as well in this respect. The results of Prud’homme
and co-workers (1984) suggest that trainability of maximal oxygen consumption also depends on individual genotype, that is,
adaptive responses to training are determined in part by genes.
Nevertheless, research data confirm the common observation
that overfat children perform poorly on exercise tasks, particularly in weight-bearing activities. Watson (1988) described an
average 46 yd decrement in distance covered in a 12 min
walk/run test for each 1% increase in body fat content in a
group of adolescent boys. Body fat content over a definite level
(25%) may also have a significant influence on the results of
laboratory exercise tests especially in non-athletic children.
The aim of the study was to compare the selected measured
and calculated spiroergometric characteristics evaluated as a
function of relative body fat content.
Methods
A total of 97 volunteer, healthy but non-athletic boys, living in
the capital were tested in the spring of 2002. Their calendar
age ranged between 9.51 and 10.50 years. The boys and their
parents were informed about the aims and every technical
40
details (risks) of the investigation and the written consents
were also collected. Three subgroups were formed by their
weight-related body fat content (F%) estimated by the suggestions of Parízková (1961).
— Subgroup 1: F% < 24.9; n = 35; normal fat group,
— Subgroup 2: F% is between 25.0-29.9; n = 41; fat group,
— Subgroup 3: F% > 30.0; n = 21; obese group.
The members of Subgroup 1 and 2 took part in the curricular
PE classes only, the obese children because of their high body
fat content were edged on adapted physical education.
Body build was characterised by the metric index (Conrad
1963). This indicator is the ratio of chest depth and width
(corrected by the stature) and describes the constitution
between the picnomorphic and leptomorphic extremes. The
more positive the metric index, the more picnomorphic the
physique is. Stages of genital development were described by
the Tanner scores (Tanner 1962). In taking the anthropometric
dimensions the IBP (International Biological Program) suggestions (Weiner and Lourie 1969) were observed. Aerobic power
and ventilatory parameters were measured during graded
exhaustive treadmill exercise, by using a Jaeger m-DATASPIR
analyser. Before the spiroergometric data collection, the children took part in a medical examination including all fields
that are officially required for general sport medical licence.
Beyond the directly measured data the aerobic power and
minute ventilation were related to body mass and lean body
mass, and the oxygen pulse was also calculated. Following individual warm up test exercise started at 4 km x h-1 belt speed
and zero inclination. Belt speed was increased in every 3 minutes by 2 km x h-1. Physical performance was expressed in
Watts. Differences between the subgroup means were analysed
by F-test, following one way ANOVA.
Results
Means, standard deviations and the summary results of one way
ANOVA are summarised in Table 1. The upper third of the table
contains the anthropometric variables, the middle one refers to
the measured physiological performances and the bottom section indicates the relative (calculated) physiological variables.
Differences between the subgroup means of anthropometric
variables were significant consistently at 5% level of random
error, nevertheless, the grater means of body mass and lean
body mass in subgroup 2 and 3 can be attributed to the sampling. Thus the obese children were markedly taller than the
fat and non-fat boys of this comparison, and more and more
picnomorphic (round shaped) morphological constitution refer
to the greater and greater relative body fat content means. The
results of all the three possible comparisons were significant in
case of metric index. The greater than 0.2 metric index unit
difference can be evaluated as extremely high and means
anthropologically various physique.
The obese boys had significantly greater peak minute ventilation and absolute oxygen consumption than the normal fat children, however, both the absolute and relative standard deviations (SD x 0.01mean-1) around the VO2 mean of obese boys
was also greater (10.53% vs. 13.24%). The statistically same
mean physical performances (watts) and the significantly different body mass means indicate the remarkably shorter exercising
time, consequently the lower peak running intensity of the
obese children. The relative measures of peak aerobic power
(VO2/kg, VO2/LBM), minute ventilation (VE/kg, VE/LBM) and
physical performance (Watt/kg) were the greatest consistently
revista
19.9.03
0:50
Página 41
in the group of normal fat boys, and the lowest in the obese
children. An almost linearly decreasing trend with increasing
body fat content can be determined by all the means of relative
indicators of aerobic power and physical performance.
Table 1. Descriptive and comparative statistics for
anthropometric and spiroergometric variables
Abbreviations: SD = standard deviation, BH = height (cm), BM =
body mass (kg), F% = relative body fat content, MIX = metric index
(cm), LBM = lean body mass (kg), HR = heart rate (beat x min-1),
VE = minute ventilation (l x min-1), VO2 = absolute aerobic power
(l x min-1), VO2/kg = aerobic power relative to body mass (ml x kg-1
x min-1), VO2/LBM = aerobic power relative to lean body mass (ml x
kg-1 x min-1), O2P = oxygen pulse (ml x beat-1), VE/kg = minute
ventilation relative to body mass (l x kg-1), VE/LBM = minute
ventilation relative to lean body mass (l x kg-1), P<5% = difference
between the means is significant at 5% level of random error,
NS = non-significant.
Among the relative performance variables only the means of
oxygen pulse (one of the useful estimates of cardiac performance during exercise) did not differ significantly. These oxygen
pulse averages were not significantly lower than the those of
the regularly training soccer players of the same age (Mészáros
et al. 1991) The standard deviations indicating the intra-group
variability were marked in all the three subgroups and all the
relative measurements. The body fat content had not significant effect on standard deviations.
Discussion
In respect of the real anthropometric differences it is suggested
to point out the early observations of Johnston and Malina
(1966). That is, the early maturing children are more or less
taller and they have significantly more subcutaneous fat
between 7 and 17 years. Such effects of the various maturity
levels cannot be excluded naturally (since neither X-ray pictures nor hormone levels were analysed in our investigation),
but the reversed order of ideas can be true either. Namely not
every 10-year-old obese boy is biologically advanced.
Nevertheless no consistent or remarkable differences were
observed between the stages of genital development. Since the
stature means of fat, obese and non-fat individuals are not different in young adulthood the effects of inheritance can also be
neglected in all certainty. Whereas the more positive mean
metric indices of the fat and obese children and adolescents are
returning results without race or ethnic differences (Mészáros
et al. 2001, Mohácsi et al. 2003, Othman et al. 2002) it is difficult to separate between the methodological consequences of
thick skinfolds around the chest and the inherited characteristics (genetically picnic body build) of the physique. The
observed mean difference between the metric indices of normal
fat and obese children was extremely high (0.42 unit) in proportions greater than the difference between the body fat content means. Since the structure of used chest calliper reduces
markedly the distorting effects of skinfolds in taking the chest
diameters, consequently the possibility of real constitutional
differences is greater. Moreover this question also needs further investigation.
Since our subjects were young and healthy (but basically
hypoactive) their absolute cardiorespiratory characteristics did
not differ significantly. Both the 1.8 l x min-1 oxygen uptake in
the normal fat children and 2.1 litre of the obese boys as exercise physiological performances can be evaluated as medium or
good. That is the other side of this problem for what physical
workload and what exercise intensity can they perform on the
medium or good exercise physiological basis.
Studies of fat and moderately obese children have failed to
indicate any evidence of human biological or physiological
impairment during exercise (Maffeis et al. 1994, Rowland
1991). The peak oxygen uptake and minute ventilation
expressed as absolute values (l x min-1) are the same even
greater in obese children compared to non-obese ones.
Nevertheless, the peak physical performance and the oxygen
economy are generally smaller in obese children.
This evidence supports the conclusion that endurance performance and relative aerobic power, relative minute ventilation are
more or less depressed in fat and obese children because of the
inert load created by their gained body fat rather than because
of a lower cardiopulmonary performance.
According to the observation of Rowland (1996) in such young
children the positive effects of regular physical activity or the
negative consequences of hypoactivity can prove rather in the
physical and less in the exercise physiological characteristics.
Consequently we cannot be satisfied with the observed
absolute or relative physical performances either of the investigated normal fat or the obese children. Since the members of
all the three subgroups need marked development in running
performance, the greater physical workout would be important
from this therapeutic standpoint.
References
Bouchard C. (2000). Physical Activity and Obesity. Human Kinetics,
Champaign, Illinois.
Conrad K. (1963). Der Konstitutionstypus. Springer Verlag, Berlin.
Frenkl R. Mészáros J. Mohácsi J. Bukta M. (1988). Young athletes;
biological, physiological, and educational perspectives. Human Kinetics
Publishers, Inc., Champaign, Illinois, 93-97.
Johnston FE. Malina RM. (1966). Human Biology, 38: 1-21.
Maffeis C. Schena F. Zaffanello M. Zoccante L. Schutz Y. Pinelli L.
(1984). Acta Paediatr., 83: 113-116.
Malina RM. Bouchard C. (1991). Growth, maturation, and physical
activity. Human Kinetics Books, Champaign, Ill. 385-388.
Mészáros J. Petrekanits M. Mohácsi J. Farkas A. Frenkl R.
(1991).Papers of the Scientific Session in Szeged (Hungary). SzegedUlm, 181-187.
Mészáros J. Othman M. Szabó T. (2001). The exchange and development
of sport culture in east and west. NTNU-AIESEP, Taipei, 102-103.
41
revista
19.9.03
0:50
Página 42
Mohácsi J. Lee CP. Zsidegh M. Tatár A. Mészáros J. (2002).
Collegium Anthropologicum. 26: 142.
Othman M. Sziva Á. Mészáros J. Mohácsi J. (2000). Kalokagathia,
75th Anniversary, Special Issue, 152-157.
Othman M. Lee CP. Soliman YA. Mészáros J. Mohácsi J. (2002):
XXVII FIMS World Congress of Sports Medicine, Abstracts, Budapest,
2002. 101.
Parizková J. (1961). Metabolism, 10: 794-807.
Prud’homme D. Bouchard C. Leblanc C. Landry F. Fontaine E.
(1984). Med.Science in Sports and Exercise, 16: 489-493.
Rowland T. (1991). Amer. Journal Dis. Child., 145: 764-768.
Rowland T. (1996). Developmental exercise physiology. Human
Kinetics, Champaign, Illinois.
Tanner JM. (1962). Growth at Adolescence (2nd edition). Blackwell
Scientific, Oxford.
Watson AWS. (1988). Ir. Journal Med. Sci., 157: 383-384.
Weiner JES. Lourie JA. (Eds.)(1969). Human Biology. A Guide to
Field Methods. IBP Handbook, No. 9. Blackwell Scientific Publishers,
Oxford.
42
revista
19.9.03
0:50
Página 43
PSYCHO-SOCIAL ASPECTS
revista
19.9.03
0:50
Página 44
revista
19.9.03
0:50
Página 45
VALIDATION OF THE CHILDREN’S OMNI PERCEIVED
EXERTION SCALE FOR STEPPING EXERCISE
Robertson Robert J, Goss Fredric, Andreacci Joseph, Dube John,
Rutkowski Jason, Snee Brooke, Kowallis Ruth, Crawford Kim,
Metz Kenneth
Center for Exercise and Health-Fitness Research,
University of Pittsburgh, Pittsburgh, PA , USA
Keywords: perceived exertion, OMNI scale, stepping
Introduction
This investigation validated the newly developed stepping pictorial format of the Children’s OMNI Perceived Exertion Scale
using a concurrent paradigm. The term OMNI is an acronym
for the word omnibus and when defined in the context of a
perceived exertion metric refers to a category scale having
broadly generalizable measurement properties. The OMNI
Scale has a developmentally indexed category format that contains both pictorial and verbal descriptors positioned along a
comparatively narrow numerical response range, i.e. category
range 0 to 10. The “exertional meaning” of the four pictorial
descriptors is consonant with corresponding verbal descriptors.
In this way, the range of numerical category responses that
comprises the OMNI Scale is defined by both pictorial and verbal descriptors. To be valid and functional over a wide range of
physical activity and sport settings the Children’s OMNI Scale
employs interchangeable sets of mode specific pictorial formats. The pictorials are arranged in ascending order of perceptual-cognitive intensity along a visually discernable response
gradient, i.e. a hill. Using this psychometric concept, the basic
numerical and verbal components of the standard scale format
are invariant. The pictorial descriptors are interchangeable to
be consistent with the exercise mode to be performed. Of practical importance in developing this scale was the expectation
that the pictorial-verbal exertional format could be used by
female and male children while participating in a wide range of
exercise modes.
Pictorial descriptors depicting a youth cyclist and walker/runner have been developed and validated previously for use with
the OMNI Scale. The present investigation validated the psychometric properties of stepping pictorials for the Children’s
OMNI Scale. Stepping is a ubiquitous element of a child’s daily
activities. Movements involving stepping are often part of
health-fitness exercises, physical education classes and various
sports. The concurrent validation of a mode specific pictorial
format to assess exertional perceptions during stepping was
expected to further extend the generalizability and practicality
of the Children’s OMNI Scale of Perceived Exertion.
Methods
Scale validity was examined for separate groups of female
(n=12) and male (n=12) children, 8 to 12 years old. Peak oxygen consumption for the combined subject group was 48.0±3.1
ml.kg-1.min-1. A perceptual estimation protocol employing a
load incremented step test was used to establish concurrent
scale validity. An electronic stepping ergometer modified for use
by children was employed. Ratings of perceived exertion (RPE)
were determined by the Children’s OMNI-Stepping Scale.
Criterion variables were oxygen uptake (VO2; ml.kg-1.min-1) and
heart rate (HR; beats.min-1) and concurrent variables were RPE
for the overall body (RPE-O), legs (RPE-L) and chest (RPE-C).
Variables were measured at the end of each continuously presented 3-min sub-peak step test stage.
Results
The range of responses over the test stages for the combined
female and male sample was, VO2: 12.0 to 43.2 ml.kg-1.min-1;
HR 94 to 174 beats.min-1 and RPE-O, RPE-L and RPE-C: 1.0 to
9.2. Correlations and linear regression analyses were performed separately for females and males and for the total sample using repeated measures over test stages. For all correlation/regression analyses, RPE-O, RPE-L and RPE-C distributed
as positive linear functions of both VO2 and HR; r = 0.82 to
0.93 p<0.05. Differences between RPE-L and RPE-C were
examined with ANOVA for a repeated measures paradigm.
RPE-L was higher (p<0.05) than RPE-C at all test stages.
Conclusion
The perceptual-physiological responses established concurrent
validity of the Children’s OMNI-Stepping Scale over a wide
metabolic intensity range. The OMNI-Stepping Scale is an
effective metric to assess both undifferentiated and differentiated RPE in young children.
THE EFFECTS OF RANDOMISED CONTROLLED EXERCISE
INTERVENTION PROGRAMME ON THE PSYCHOLOGICAL
WELL BEING AND PHYSIOLOGICAL HEALTH OF CHILDREN
WITH TYPE 1 DIABETES
Edmunds Sarah, Roche Denise, Stratton Gareth, Glenn Sheila,
Wallymahmed Aktar
Liverpool John Moores University, Liverpool, UK
Keywords: Type 1 diabetes, exercise intervention, psychological
well being
Introduction
Maintenance of blood glucose control and psychological well
being are both important health outcomes for children with
Type 1 diabetes. Diabetes management, the balance of insulin,
diet and exercise, interacts with all aspects of these children’s
health. Of these the least research has been conducted on the
effects of exercise on the health of children with diabetes this
is particularly so for the psychological effects. Phase one of
this study found greater vigorous physical activity was significantly associated with higher perceived attractive body competence. To the authors’ knowledge, no previous studies have
examined associations between physical activity and psychological well being in children with Type 1 diabetes and no
exercise intervention studies have been reported which assess
psychological outcomes for this group. However, several exercise intervention studies have assessed aerobic fitness as outcome measure, eight out of nine studies found an increase in
peak VO2, Landt et al (1985) found lean muscle mass
increased in the experimental but not the control group following an exercise intervention with 15 children aged 15 to 16
years with Type 1 diabetes. In healthy children participation in
exercise is associated with greater psychological health
(Health Education Authority 1998).
45
revista
19.9.03
0:50
Página 46
The aim of the present study was to investigate the effects of a
12-week randomised controlled exercise intervention programme on the psychological and physiological health of children with Type 1 diabetes. The hypotheses were that increasing physical activity would increase physical self esteem and
lower body fat.
Methods
Ethical approval was obtained from three NHS Trusts in the
North West of England. Participants were aged 9-15 years, diabetes duration greater than two years. Recruitment was
through diabetes clinics in three hospitals, invitations to participate were sent out via the local diabetes nurse to all eligible
families. Thirty-nine children participated in the study, these
were randomly assigned to the experimental (n=27) and control groups (n=12). More children were assigned to the experimental group to allow for the greater expected drop out rate
from this group. Of those recruited fourteen experimental and
seven controls completed the study.
The experimental group participated in two exercise sessions a
week for the first eight weeks of the programme and three sessions a week for the last four weeks. Sessions were designed to
include high intensity activity. However, due the low levels of
vigorous physical activity found during phase 1 the intensity
was increased gradually over the course of the programme.
Exercise was mainly aerobic mixed with some anaerobic exercise, activities were run as games or fun type activities.
Sessions were one hour duration and ran concurrently at three
locations in the North West of England. Children kept a record
of the sessions attended by collecting a stamp after each session. These related to a series of prizes (e.g. baseball cap, T
shirt) that they could collect after attending a certain number
of sessions. Intensity of the sessions was recorded using heart
rate monitoring (Polar, Sportstester, Kempele, Finland). Two
children were monitored at fifteen sessions, 26 data files were
recorded successfully. The control group maintained their usual
physical activity pattern.
Data were collected in the study laboratory for all participants
before and after the intervention. Children completed the
Physical Self Perception Profile for Children (Whitehead,
1995). This is a measure of physical self esteem that has been
shown to have acceptable validity and reliability with healthy
children in this age group from both US (Whitehead 1995) and
UK (Biddle 1993) populations It contains six subscales: global
self worth, physical self worth and its subdomains perceived
sport competence, perceived condition competence, perceived
attractive body competence and perceived strength competence. Each subscale contains six items, these are scored from
one to four, and a mean value calculated for the subscale. Body
mass, stature and sum of 5 skinfolds (bicep, tricep, subscapular, suprailiac and calf) were measured. Two way ANOVA calculations between time and group were conducted, except where
there were significant differences between the groups at time 1
when ANCOVA was conducted, or parametric assumptions
were not met in which case the Wilcoxon Signed Ranks test
was performed.
Results
The mean (95%CI) number of minutes spent above 75% of
maximum heart rate reserve during the exercise sessions was
13.8 (10.2 to 17.5) minutes. A mean of 9.6 (7.8 to 11.4) minutes were spent between 60 and 75% of maximum heart rate
46
reserve and mean 6.8 (5.4 to 8.2) minutes between 50 and
60% of maximum heart rate reserve.
When differences between the groups at time 1 were taken
into account the only significant interaction between time and
group was for BMI, this increased in the experimental group
between times 1 and 2 and decreased slightly in the control
group (F= 4.77, p= 0.04). Sum of skinfold measurements
decreased in both groups over time, this difference approached
significance (p=0.05). There was a non significant interaction
between time and group in the hypothesised direction for perceived sports competence and perceived condition competence.
Perceived strength competence increased significantly in both
groups (p<0.05). There was no significant effect on the other
subscales, data are reported in table 1. Sample size was small
and therefore the results must be treated cautiously due to the
possibility of Type 2 error.
Table 1: Mean values by experimental and control groups at times 1 and 2
aScale
from the Physical Self Perception Profile for Children, range 1-4,
1= lowest possible competence 4= highest possible competence.
Discussion
It is suggested that the increase in the BMI of the experimental
group was due to an increase in the muscle mass of this group.
Although this was not measured directly the decrease in skinfold thickness supports the suggestion. Increases in perceived
condition and sport competence in the experimental group
were encouraging as higher physical self perceptions are associated with greater physical activity and may therefore lead to
long term increases in physical activity. The changes found to
occur in both groups between times 1 and 2, increased
strength competence and decreased skinfold thickness, were
likely to have been due to maturation; mean increase in height
during the study period indicates some children were going
through puberty. It is suggested that an intervention programme that incorporated physical activity and an educational
or cognitive component would have a greater effect on the outcomes studied.
References
Biddle SJ et al (1993). Int J Adolesc Youth 4, 2: 93-109
Health Education Authority (1998). Young and active? Policy framework for young people and health-enhancing physical activity
Landt KW et al (1985) Diabetes Car. 8, 5: 461-465
Whitehead JR (1995). Pediatr Ex Sci 7, 2: 132-51
revista
19.9.03
0:50
Página 47
THE UTILITY OF PHYSICAL SELF-PERCEPTION IN THE
PREDICTION OF ACTIVITY COUNTS IN BOYS AND GIRLS
Parfitt Gaynor, Capel-Davies Anna
University of Wales, Bango, Wales, UK
Keywords: physical self-perception, importance, habitual activity
Self-perception has been shown to be central to models of
sport and exercise behaviour. Developments in the last decade
have enabled us to assess physical self-perception sub-domains
and the personal importance attached to each sub-domain
within a young population. The aim of this study is to investigate whether the physical self-perception sub-domains predict
activity (measured using pedometery) in boys and girls
(age=9.6yrs, SD=0.7) or whether the importance attached to
these physical sub-domains provides a better predictor.
21 boys and 26 girls completed the Children’s Physical Selfperception Profile (C-PSPP) and the Perceived Importance
Profile (C-PIP). Habitual activity was assessed with the use of
hip pedometers over a period of seven days.
Analyses indicated that there was no significant difference
between the number of counts recorded for the boys
(M=13396, SD=4857) and girls (M=12483, SD=3872). There
were differences between the C-PSPP and C-PIP for the boys
and girls. Multivariate analyses indicated that boys had higher
levels (P<0.01) of Sports Competence (M=19.33, SD=3.89),
Physical Strength (M=17.81, SD=4.22), Sports Competence
Importance (M=7.19, SD=1.20) and Physical Strength
Importance (M=7.76, SD=4.21) compared to the girls
(M=16.61, SD=4.22; M=15.11, SD=3.75; M=6.23, SD=1.30;
and M=5.57, SD=1.47, respectively). Regression analyses indicated that the physical sub-domains predicted 51.3% of the
variance in the activity counts of the girls and 43.3% of the
variance in the activity counts of the boys, whilst the importance attached to the sub-domains predicted 37.6% in the girls
and 59.1% in the boys.
These results suggest that the physical sub-domains were a
better predictor of activity count in girls but that the importance attached to each domain were a better predictor in boys.
The implication of these results from an intervention perspective is that to improve the physical activity in these girls and
boys it would be important to focus upon different elements of
physical self-perceptions (the actual domains in girls, but the
importance attached to them in boys).
is a relationship between adiposity and social deprivation.
Participants (boys n=460, girls n=405) aged 9-14 years from
12 schools across Merseyside (UK) were included in the project. Stature (m), mass (kg) and skinfold (triceps, calf, subscapular and suprailiac) measures were recorded using standardised anthropometric procedures. The sum of triceps and
calf skinfold and the sum of four skinfolds were used to identify percentage body fat and provide an adiposity rating. The
Townsend Index was used to determine levels of social deprivation, it is based on census information about the area in which
the individual lives and takes into account the proportion
unemployed, percentage of households with no car, the percentage of households with overcrowding and the proportion
of non-occupied households. Descriptive statistics were used to
identify the prevalence of obesity and Spearman rank correlation was performed to identify the relationship between adiposity and social deprivation. Significance was set at P<0.05.
Overall only 52.5% (n=240) of the boys and 47.4% (n=192)
were classified as optimal adiposity using the triceps and calf
skinfold. Of the boys 20.0% (n=92) were classified as moderately high adiposity, 13.3% (n=61) as high adiposity and
14.6% (n=67) as very high adiposity. Of the girls 20.2%
(n=82) were classified as moderately high adiposity, 16.3%
(n=66) as high adiposity and 14.6% (n=59) as very high adiposity. In comparison to the ratings from the Northern Ireland
Fitness survey 36.5% of boys and 48.9% of girls were above
the 80th percentile for the sum of four skinfolds. The mean
percentage body fat per age group ranged from 18.7% to 22.7%
for boys with the lowest level at 14 years. The mean percentage
body fat per age group ranged from 27.8% to 29.8% for girls
and was similar across all age groups. These findings indicate
high levels of above normal adiposity in both boys and girls,
indicating high levels of obesity. Correlation coefficients
between social deprivation and the adiposity measures ranged
from r=-0.09 (sum of four skinfolds, p>0.05), r=-0.09 (fat
percentage, p<0.05) and r=-0.08 (sum of triceps and calf skinfold, p>0.05). These indicate very slight negative relationships
between adiposity and social deprivation.
Overall it was concluded that obesity is a significant problem
in children aged 9- to 14- years in the Merseyside region. Social
deprivation showed little relationship to adiposity. Further
research is needed to monitor trends in overweight and obesity, and to monitor the effectiveness of national strategies
intended to alleviate this increasing problem.
RELATION OF EATING BEHAVIOUR WHILE WATCHING TELEVISION
WITH ADIPOSITY IN CHILDREN FROM 8 TO 12 YEARS
ADIPOSITY LEVELS IN 9 TO 14-YEAR OLD BOYS AND GIRLS:
DATA FROM THE MERSEYSIDE SPORTS-LINX PROJECT
Hitchen Peter, Stratton Gareth, Jones Michelle
Jauregui Edtna, Jimenez Antonio, Lopez Taylor J
Institute of Applied Sciences of Physical Activity and Sports University
of Guadalajararsity of Guadalajara, Mexico
Edge Hill College, England
Keywords: eating behaviour, television, adiposity
Keywords: obesity, social deprivation, adiposity
Obesity is characterised as a state of excessive adiposity and in
recent years has been identified as an increasing public health
concern in children. The aim of the current study was to identify the prevalence of obesity in children and establish if there
Objective
To determine the eating behaviour while watching television
and adiposity in children.
47
revista
19.9.03
0:50
Página 48
Material and Methods
A survey was carried out on a representative sample of children
aged 8 to 12 years old (417 girls, 444 boys) in Guadalajara,
Mexico, in which five skinfolds were measured. Multiple
regression analysis were used for statistical purposes.
Results
We found the same pattern of increased hours of watching television as reported for an American children population (from
36.5% aged 8 years to 39.8% of 12 year olds watched television
for more than 4 hrs. a day per week). There were no significant
differences by sex. In general more than 85% spent 2.8 hrs. a
day and about 21 hrs. per week watching television while eating different types of food (8.6% ate meals such as lunch and
dinner and 86% ate snacks such as potato chips, candies and
chocolates). There is a statistically significant association that
shows that the children who had more adiposity were the ones
that spent more time eating and watching television.
Conclusions
In comparison with other reports, the data showed that our
children watched more television and snaked more while viewing TV. We concluded that the problem of watching television
and eating, especially snacks, is related to the need of supervision of the children by the parents, lack of physical and recreational programs and a lack of knowledge of the benefits of
doing physical activity. Finally, we believe that television has
become an icon of recreation, entertainment and time to eat for
children in our country, thus contributing to the development of
a new society characterized by a population of fat people with
all the social, health and cultural problems related to this issue.
48
revista
19.9.03
0:50
Página 49
CLINICAL/MEDICAL ASPECTS
revista
19.9.03
0:50
Página 50
revista
19.9.03
0:50
Página 51
EXERCISE PERFORMANCE AND GROWTH STATUS IN EIGHT TO TEN
YEAR OLD CHILDREN WITH CYSTIC FIBROSIS
McBride Michael3, Schall Joan1, Zemel Babette1,
Cohen Jacqueline1, Scanlin Thomas2, Stallings Virginia1,
Paridon Stephen3
1
Division of Gastroenterology, The Children’s Hospital of
Philadelphia, Philadelphia, Pennsylvania
2 The Cystic Fibrosis Center, The Children’s Hospital of Philadelphia,
Philadelphia, Pennsylvania
3 Division of Cardiology, The Children’s Hospital of Philadelphia,
Philadelphia, Pennsylvania
Keywords: maximum oxygen uptake, pulmonary disease, nutrition
Introduction
Cardiopulmonary exercise performance in individuals with cystic
fibrosis (CF) is influenced by both pulmonary and nutritional
factors. Pulmonary function may limit exercise performance due
to the use of greater minute ventilation to compensate for the
increased dead space. Consequently, the ratio of peak minute
ventilation to maximal voluntary ventilation often exceeds the
normal range of 60% to 70%, limiting mechanical ventilatory
reserve. Decreased nutritional status may impair exercise performance through the loss of skeletal muscle mass and changes
in the quality of the remaining muscle. Previous studies aimed
at identifying the limitations and associated predictors of exercise performance in individuals with CF have found that pulmonary function plays an important role secondary to nutritional status in adolescents and adults with CF. As yet, little or no
data exist which has examined the factors that influence cardiopulmonary exercise performance in young, preadolescent
children with CF. The purpose of this study was to explore the
relationships among growth, nutritional and pulmonary status
and exercise performance in a large cohort of preadolescent children with CF and pancreatic insufficiency (PI).
Methods
Children with CF and PI (6.0 to 8.0 yrs) were enrolled from 13
U.S. CF Centers as part of a 2-year study of growth and nutritional status and pulmonary function. Eligibility included an
FEV1 > 40% predicted values. Exercise performance was
assessed at the 2-year visit. Each subject performed a maximal
treadmill or cycle ergometer exercise test. The protocol consisted of 3 minutes of pedaling in an unloaded state followed
by a ramp increase in work rate to maximal exercise. Two subjects were exercised using a treadmill protocol. Three minutes
of walking was followed by 1-minute incremental ramp
increases in speed (m.p.h.) and grade (%) to maximal exercise.
Resting lung mechanics were obtained and consisted of inspiratory and expiratory flow volume loops. Metabolic data were
obtained throughout exercise and during the first 2 minutes of
recovery on a breath-by-breath basis. Indices of aerobic capacity (MVO2), peak minute ventilation (VE), breathing reserve
(BR) pulmonary function (FEV1), and physical working capacity (PWC) were measured and % predicted values reported. For
growth status, Z scores for height (HT), weight (WT), and
body mass index (BMI: kg/m2) were calculated using the 2000
U.S. Center for Disease Control reference values. For nutritional status, Z scores for upper arm circumference (UAC),
upper arm muscle area (UAMA), and upper arm fat area
(UAFA) were calculated using National Center for Health
Statistics reference values. Using backwards stepwise regression, potential predictors of exercise performance (FEV1, UACZ, UAMA-Z, UAFA-Z) were evaluated for their association
with each of the primary outcome variables (MVO2, PWC).
Results
Sixty-five children (ages = 9.3±1.0 years, 33 male) with mild
pulmonary disease (FEV1 = 90±14% predicted) were included
in this study. The mean values for MVO2 (95±20% predicted)
and PWC (97±20% predicted) for the cohort were within normal limits for age- and sex-matched healthy children. VE
(81±14% predicted) at peak exercise was lower than normal but
did not appear to impact exercise performance (BR = 22±8.2).
Girls differed significantly from boys in VE (77±13% vs.
86±13%, respectively, p=0.007), but not in MVO2 (94±20% vs.
96±20%, respectively) or PWC (94±17% vs. 99±20%, respectively). Further examination revealed five distinct groups
emerged from the data. Low MVO2 (71±15%), low PWC
(82±10%), and anaerobic threshold (AT) data (70±11% of peak
MVO2) suggested musculoskeletal de-conditioning in 5 subjects.
Eight subjects exhibited mildly reduced MVO2 (76±9%), normal
PWC (91±14%), normal FEV1 and FVC (102±8%, 97±10%),
and normal BR (24±6%). Low BR (8±4%) were present in 28
subjects without significant impact on MVO2 (107±12%) or
PWC (103±18%). Pulmonary abnormalities (FEV1=74±8%,
BR=8±4%) were present in 8 subjects which appeared to
impact exercise performance (MVO2=68±9%, PWC=80±17%).
The remaining subjects (n=16) exhibited normal responses in
cardiopulmonary exercise performance (MVO2=104±17%,
PWC=100±20%, BR=24±8%). Overall, growth status was suboptimal (HT-Z= -0.5±1.1, WT-Z= -0.4±1.2, BMI-Z= -0.2±1.1)
in the subjects, with normal nutritional status based upon UACZ (-0.1±1.2) and UAMA-Z (0.2±1.2). Girls tended (p<0.10) to
have lower BMI-Z compared to the boys (-0.4±1.0 vs. 0.1±1.2)
and lower UAC-Z (-0.4±1.0 vs. 0.1±1.2). As common in
healthy children, BMI was negatively associated with both
MVO2 and PWC (r = -.46 and r= -.38, respectively, p<0.01).
Using backwards stepwise regression (significance level,
p<0.20), and adjusting for age, gender, and BMI, the best positive predictors of MVO2 were FEV1 (p=0.05) and UAMA-Z
(p=0.03), with a total R2=.37.
Table 1: Characteristics of Study Population (mean±S.D.) (*p<0.10).
Table 2: Exercise Parameters at Peak Exercise (mean±S.D.) (*p=0.007).
51
revista
19.9.03
0:50
Página 52
OXYGEN UPTAKE KINETICS ARE SLOWED IN CYSTIC FIBROSIS
Hebestreit Helge, Hebestreit Alexandra, Trusen Andreas,
Hughson Richard
Universitäts-Kinderklinik Würzburg, Germany
Keywords: oxygen uptake, cystic fibrosis, kinetics
Figure 1: Comparison of Peak Oxygen Uptake
and Upper Arm Muscle Area.
Discussion
Data from this study represent a comprehensive analysis of the
overall exercise performance and factors that predict performance in young children with CF and PI. Similar to previous
studies in adolescents and young adults, this data indicate that
exercise performance in CF is determined by the degree of
underlying pulmonary disease, nutritional status, growth status, or a combination of these factors. However, wide ranges of
age have limited previous study’s ability to make conclusions
specific to age and identify the presence of any sub-groups
identified in this study. Data from this study demonstrate that
overall performance during exercise was normal in this sample
of preadolescent children with CF and PI. Overall, growth status was sub-optimal, and nutritional status was sub-optimal in
girls. After adjusting for confounding variables, both pulmonary function and lean body mass positively and significantly predicted exercise performance. Patients with chronic lung
disease can be limited by their ventilatory capacity. Peak VE
during aerobic exercise in subjects with chronic lung disease is
usually very close to maximal voluntary ventilation, suggesting
that they have little or no breathing reserve. In this group of
young children with CF and PI the lower VE (and subsequent
low BR) noted at peak exercise did not appear to significantly
impact exercise performance. This may be explained by the
cohort’s relatively mild underlying pulmonary disease.
Although the cohort as a whole exhibited normal indices of cardiopulmonary exercise performance, there appears to be a number of sub-groups that display varied responses to cardiopulmonary exercise performance. Underlying pulmonary disease
and nutritional status impacted overall exercise performance in
eight of the subjects, whereas, in the remaining subjects
(n=57) underlying disease had little or no effect at this point to
impact exercise performance. These findings indicate the
importance of routine evaluations of cardiopulmonary exercise
performance, growth and nutritional status, and pulmonary
function young children with CF to assess disease severity and
changes in the cardiorespiratory responses to exercise that
occur with disease progression into adolescence and adulthood.
References
Lands et al. (1992), Clinical Science 83:391-97
Cooper et al. (1984), J Appl Physiol 56:628-34
Marcotte et al. (1986), Pediatr Pulmonol 2:274-81
Frisancho RA (1993), Anthropometric Standards for the Assessment
of Growth and Nutritional Status
Nixon PA (1997), Exercise Management for Persons with Chronic
Diseases and Disabilities
Shah et al. (1998), Res Crit Care Med 157 (4):1145-50
52
There are conflicting reports on the kinetics of oxygen uptake
at the onset of exercise in patients with cystic fibrosis (CF).
The objective of the present study was, therefore, to compare
oxygen uptake (VO2) kinetics in CF-patients to those of
healthy controls (CON). 18 CF-patients (FEV1 37-98%predicted) and 15 CON aged 10 to 33 years completed 2-4 transitions
from low intensity cycling (stage 1-20 W) to cycling at 1.3-1.4
W/kg body weight (stage 2) in a semi-supine position. There
was no difference between groups in heart rate at stages 1 and
2 or in relative exercise intensity, as expressed as %VO2peak or
percentage of ventilatory threshold. VO2-data of stages 1 and 2
were interpolated second-by-second, time-aligned, and averaged. Mono-exponential equations were used to describe phase
II VO2-responses. While there was no difference between CF
and CON in time delay (16.6±5.5 vs. 19.6±5.5 s) or amplitude
(11.0±1.7 vs. 10.2±1.6 ml/W) of phase II VO2-response, time
constant tau was significantly prolonged in CF compared with
CON (37.3±12.5 vs. 25.6±8.7 s). Multiple linear regression
analysis using the combined data of CF-patients and healthy
controls identified oxygen saturation at peak exercise and time
delay of the phase II VO2-response as significant independent
predictors of tau (R2=0.69). When tau was adjusted for the
effects of these two variables, the difference between CF
patients and controls disappeared. In conclusion, VO2-kinetics
are slowed in CF which may, in part, be attributed to an
impairment of oxygen delivery.
SHORT-TERM EFFECT OF DIFFERENT SPORT ACTIVITIES
AND PHYSIOTHERAPY ON SPUTUM PRODUCTION AND
LUNG FUNCTION IN YOUNG PATIENTS WITH CYSTIC FIBROSIS
Kriemler Susi, Christen Gregor, Huber Martha
Department of Pediatrics, Triemli Hospital, Zürich, Switzerland
Keywords: cystic fibrosis, physical activity, sputum production
Physical activity and physiotherapy are important elements in
the daily treatment of young patients with cystic fibrosis. One
positive effect is the increase in mucus expectorations which
might lead to an improved lung function and oxygen saturation. It is, however, not clear which type of physical activity is
especially helpful. The aim of the study was therefore, to determine the effect of a combined sport-physiotherapy program,
using either trampoline or bicycle, on the sputum production,
oxygen saturation and short-term lung function in adolescents
and young adults with cystic fibrosis.
Twelve 15- to 30-year-old cystic fibrosis patients took part in
the study. They were randomly allocated into 3 groups. Each
subject performed all test protocols on 3 non-consecutive days
of a week. The bicycle and trampoline protocol included 30
revista
19.9.03
0:50
Página 53
minutes of the activity at a heart rate of 140-160 bpm, the
third group played billiard over 30 minutes. All sessions were
followed by a physiotherapy program. A 30 min break followed
the sport and physiotherapy program. Before, after the sport
activity including a 30 min break, and after the physiotherapy
including a 30 min break, a pulmonary function was performed
and the sputum production evaluated. Transcutaneous oxygen
saturation was measured initially and at the end of the combined sport-physiotherapy program. The sputum production
during trampoline was significantly higher than after billiard,
but it was not different with bicycling compared to the others.
Sport (trampoline and biking) was equally effective in sputum
production than the following physiotherapy; billiard was significantly less effective in sputum production than the following physiotherapy. Neither sport nor physiotherapy had a significant effect on the lung function. The transcutaneous oxygen
saturation increased significantly after the combined bicyclephysiotherapy and trampoline-physiotherapy program but did
not change after the billiard-physiotherapy program.
Trampoline was the preferred activity of all participants.
A daily physical activity and physiotherapy of 30 min have an
equal, but additive effect on the sputum production in adolescents and young adults with cystic fibrosis. In combination,
they lead to an improved oxygen saturation. The type of sport
does not seem to play a role.
AIRWAY OBSTRUCTION IS AN UNCOMMON CAUSE OF
EXERCISE-LIMITING SYMPTOMS IN PEDIATRIC PATIENTS
WHO DO NOT HAVE HISTORICAL FEATURES OF ASTHMA
bronchitis and/or pneumonia, recurrent and prolonged cough,
frequent nighttime symptoms).4 Of the 294 patients screened,
120 (41% of total) answered no to all screening questions and
comprise the study population. Patients had baseline spirometry performed and then underwent treadmill stress testing with
a rapidly progressive workload aiming to reach a heart rate
>170 bpm within 2 minutes of starting and then maintain that
workload until unable to continue because of symptoms or
exhaustion. Spirometry was repeated 3, 6, and 10 minutes after
completion of exercise. Exercise induced bronchospasm (EIB)
was defined as >10% fall in forced expiratory volume in 1 second (FEV1) or >20% fall in forced expiratory flow 25-75%
(FEF 25-75%) post exercise.5
Results
One patient was unable to perform spirometry. In the remaining 119 patients comprising the study group, age ranged from
6-18 years (mean 12 years), and there were 57 males and 62
females. Twenty seven study patients (23%) were on or had
recently been treated with asthma medications. Of the 119
patients, 8 (6.7%) had airway obstruction identified—3
patients had abnormal spirometry values and flow/volume
curves at baseline that did not worsen after exercise but corrected after nebulized albuterol, and 5 patients met diagnostic
criteria for EIB. Ninety one patients (76%) had their presenting
symptoms reproduced during stress testing. In these 91
patients, 6 (6.6%) had airway obstruction identified. Alternate
diagnoses were made or suspected in 69 of the 111 patients
(62%) without identifiable airway obstruction including poor
fitness (31), poor breathing technique or hyperventilation (20),
costochondritis (15), vocal cord dysfunction (1), vasovagal
response (1), sensing appropriate sinus tachycardia (1).
Biros Patricia, Hasbani Keren, Ziegler James W
Department of Pediatrics, Hasbro Childrens Hospital and Brown
University, Providence, RI, USA
Keywords: exercise, asthma, stress testing
Introduction
Exercise intolerance and/or exercise-limiting chest symptoms
are common complaints in pediatric patients that often result
in medical referral. Several studies suggest that airway
obstruction is a common cause of exercise-limiting symptoms,
even in patients who do not have historical features of
asthma.1-3 Based on these studies and a prevalent concern
regarding the underdiagnosis of asthma, it has become common practice to prescribe asthma medications to pediatric
patients with exercise-limiting symptoms and assess symptom
responsiveness as a means of ruling in/out airway obstruction.
The goal of this study was to determine the incidence of airway
obstruction as a cause of exercise-limiting symptoms in children and adolescents without historical features of asthma.
Methods
294 pediatric patients were referred to our pediatric cardiopulmonary laboratory for evaluation of exercise-limiting symptoms
including exercise intolerance, excessive dyspnea, chest discomfort, cough, or 2 or more symptoms in combination. Patients
were screened by questionaire for historical features suggestive
of underlying airway disease (asthma diagnosed in past by medical provider, previous wheezing episodes, 2 or more episodes of
Conclusions
1. In pediatric patients without historical features of asthma,
airway obstruction is an uncommon cause of exercise-limiting
symptoms;
2. In this patient population, asthma medications should not be
prescribed without first comfirming the diagnosis of asthma;
3. Using a progressive treadmill protocol, symptoms can be
reproduced in a majority of patients, and alternate diagnoses
can be made or suspected in a high percentage.
References
1. Wiens L et al (1992)Pediatrics 90:350-353
2. Rupp NT, Guill MF, Brudno S (1992) AJDC 146:941-944
3. Nudel DB et al (1987) Clinical Pediatrics 26:388-392
4. Clinical Practice Guidelines (1997), NIH publication No. 97-4051
5. Custovic A et al (1994) Chest 105:1127-1132
EXERCISE INDUCED STRIDOR — VISUALISING THE PROBLEM
Skadberg Britt, Halvorsen Thomas, Heimdal John Helge,
Roksund Ola D
Pediatric Department, Haukeland University Hospital, Bergen, Norway
Keywords: exercise induced asthma, vocal cord dysfunction, exercise
induced laryngeal dysfunction
53
revista
19.9.03
0:50
Página 54
Exercise induced asthma (EIA) is characterised by breathing
difficulties and wheeze subsequent to physical activity. Vocal
cord dysfunction (VCD) and exercise-induced laryngomalacia
(EIL) are characterised by shortness of breath, stridor, chestpain and occasionally immense fear occurring during exercise.
Both entities may mimic EIA. Misdiagnosed EIA should be
avoided to prevent potentially harmful and unnecessary medication. In our experience, exercise induced stridor is more
prevalent than previously reported. Despite extensive diagnostic work-up, however, upper airway pathology was only infrequently verified in our patients. To improve patients work-up, a
standardised diagnostic program including a questionnaire,
clinical examination, spirometry, metacholine provocation, a
classification system for laryngeal pathology and videorecorded
transnasal flexible laryngoscopy during tread mill exercising,
was developed. Fifteen non-symptomatic, healthy controls and
40 children and adolescents experiencing stridor during exercise testing, were studied. Laryngoscopy with simultaneous
videotaping was performed while subjects were running to
exhaustion. Parameters of gas exchange, exercise flow volume
loops and clinical data such as breath sounds and other signs
of stridor were continuously recorded. Every control subject
had normal laryngeal function at rest, during and after exercising. Abnormalities were demonstrated in the majority of symptomatic subjects. A variety of laryngeal pathology, ranging from
mere vocal cord dysfunction to obviously enlarged aryepiglottic
folds and combinations of the two, were recognised. Medial
motion of the dorsal part of the aryepiglottic folds was the
most frequent finding. Exercise induced stridor in children and
adolescents admitted for EIA test rather than particular flow
volume patterns and/or metacholine response, predicted positive laryngoscopy.
Conclusions: Exercise induced laryngeal dysfunction (ELD) is
not uncommon in subjects complaining of exercise induced
respiratory symptoms. Exercise testing to complete exhaustion
or until presentation of symptoms under close observation of
respiratory pattern, is highly recommended. If inspiratory stridor occurs, transnasal flexible laryngoscopy (ETNL) during
exercise should be performed.
A detailed presentation of the method and specific findings of
normal and dysfunctional upper airways will be presented.
Methods
Healthy children ages 8-17 years free from cardiopulmonary
disease were recruited for the current study. Maximal symptom
limited exercise was performed using a cycle ergometer and a
Sensormedics metabolic cart. Forty-two children at ALT formed
the study group and were compared to a population of 171
children at SEA. Appropriate institutional review and approval
was given from the University of Arkansas Children’s Hospital
and the Denver Children’s Hospital. All subjects and their parents signed written informed consent. Data was analyzed using
non-paired t-tests and is presented below as mean +/- SD.
Results
Subject demographics are presented in Table 1.There were no
differences in age (13.61 +/- 2.6 vs. 14.08 +/- 2.6 yrs;
p=0.584), gender (57 vs. 56 % males; p=0.942), height
(162.16 +/- 15.9 vs. 164.82 +/- 15.0 cm; p=0.334) or weight
(57.54 +/- 17.3 vs. 54.76 +/- 14.4 kg; p=0.343) between subject groups. Significant differences were noted in several cardiovascular parameters and are presented in Table 2. Children
at ALT had a lower absolute peak oxygen consumption (2.39
+/- 0.9 vs. 1.99 +/- 0.7 L/min; p=0.02) and when the oxygen
consumption was corrected for body weight (40.98 +/- 8.3 vs.
36.40 +/- 7.8 ml/kg/min; p=0.001). Children at ALT further
demonstrated a reduced oxygen pulse (12.49 +/- 4.8 vs. 10.81
+/- 3.6 ml/beat; p=0.04) and a reduced rise in oxygen pulse
slope (0.93 +/- 0.4 vs. 0.67 +/- 0.2; p<.0001). Greater ventilatory inefficiency, as evidenced by a greater ∆VE/∆VCO2, was
seen in children at ALT when compared to children at SEA
(29.6 +/- 4.3 vs. 33.9 +/- 7.4; p<.0001), however there were
no differences in ∆VE/∆VO2 (40.4 +/- 7.1 vs. 40.9 +/- 6.8;
p=0.658) between subject groups. There was no differences in
peak heart rate (191.9 +/-11.1 vs. 192.6 +/- 11.9 bpm;
p=0.747) and peak ventilation (85.6 +/- 20.9 vs. 94.3 +/31.2 L/min; p=0.103) between subject groups.
Table 1. Demographic Variables for Subjects
CARDIOPULMONARY EXERCISE RESPONSES IN CHILDREN
AT ALTITUDE AND SEA LEVEL
Taylor Amy L, Wolfe Robert R, Yetman Anji T
Department of Pediatrics, Division of Cardiology,
University of Colorado School of Medicine, USA
Keywords: altitude, exercise, children
Introduction
The effect of altitude on aerobic capacity in adults has been well
studied. There is a lack of data regarding the effect of altitude on
cardiopulmonary exercise performance in children. In addition,
the majority of altitude research is performed at extreme altitude
(greater than 10,000 feet). We sought to compare exercise performance in a group of healthy age and gender matched children
at sea level (SEA) and moderate altitude (ALT; 5280 feet).
54
Table 2. Cardiopulmonary Exercise Data for Subjects
revista
19.9.03
0:50
Página 55
Conclusion
In summary, children at moderate altitude have impaired aerobic
capacity associated with impaired ventilatory efficiency when
compared to healthy controls at sea level. The increased
∆VE/∆VCO2 at altitude may reflect an altered set point for pCO2.
IMPACT OF OBESITY ON PHYSICAL FITNESS IN USA
URBAN PEDIATRIC POPULATION
Serratto Maria
University of Illinois - JHS Hospital of Cook County, Chicago, USA
Keywords: obesity, exercise, fitness
Obesity in USA youth has reached nearly epidemic proportions
in recent years and the prevalence of type 2 diabetes has
increased dramatically. Concomitantly physical fitness (PF)of
USA children and adolescents has been declining. Recent studies have indicated that PF correlates negatively with obesity.
The objective of this study was to evaluate how obesity impacted on PF in a large urban pediatric population. Bruce treadmill
protocol was used to evaluate exercise capacity (ET) and heart
rate (HR) of 525 healthy youth 4 to 18 y/o: 303 males (M) and
222 females (F). Obesity was defined as BMI>95th percentile
for age and gender. On this basis 14% of M and 15% of F were
obese. The impact of obesity on ET for each gender was evaluated after controlling for age-group effect by testing for agegroup obesity status interaction significance. The interaction
effect was not significantly different for either gender: M
p=0,2672; F p=0,9110. The effect of obesity on ET was subsequently tested and found to be significant across all age groups
for each gender: M p<0,0001; F p=0,0001. The average
increase in ET for non-obese versus obese youth was 1,90 +/0,38 for M and 1,52 +/- 0,39 for F. For the entire group there
was a decrease in average ET of 0,0693 minutes for each unit
increase in BMI. After controlling for the effect of age-group
obesity status interaction significance, maximum HR was found
not to be statistically signficantly different between non-obese
and obese for either gender. When statistical power was
increased by grouping all non-obese versus obese youth, there
was a trend toward a decrease in peak exercise HR with
increasing BMI although the difference did not reach statistical
significance: p<0,06. In conclusion our study demonstrates
that obesity has a strong negative impact on PF in youth thus
reinforcing the necessity to promote physical activity while controlling the quality and quantity of food intake in the young.
CLUSTERING OF RISK FACTORS IN CHILDREN
Froberg Karsten1, Wedderkopp Niels1, Hansen Henrik Steen2,
Andersen Lars Bo3
1 Institute of Sports Science and Clinical Biomechanics, University of
Southern Denmark, Odense. Denmark
2 Dep. of Cardiology, Odense University Hospital, Odense, Denmark
3 Institute of Sport Sciences, University of Copenhagen, Copenhagen,
Denmark
Keywords: CVD risk factors, children, physical fitness
Introduction
Rapidly increasing rates of obesity and type 2 diabetes mellitus
have encouraged increased interest in the role of lifestyle in the
development of CVD. The protective effect of physical activity
is thought to operating through modification of the biological
risk factors for such disorders, including hypertension, hyperinsulinaemia, elevated serum total cholesterol and triglyceride
levels, low HDL-cholesterol and glucose intolerance. Clustering
of these risk factors in obese individuals (the metabolic syndrome) has been described in both children and adults.
In children many studies have investigated the relationship
between physical activity, physical fitness and CVD risk factors.
In some studies a weak relationship between physical activity
or fitness and the risk factors of the metabolic syndrome has
been described, and interpreted as lack of evidence for the preventive effect of physical activity in relation to CVD (1).
However, it may be more logical to evaluate the level of risk
and the association between the level of risk and lifestyle in
relation to clustering of risk factors instead of levels in single
risk factors in children. It is important to better understand
this relationship, since if the roots of CVD are laid down in
childhood, lifestyle modification during childhood and adolescence may be effective in lowering CVD risk in later life.
Methods
The study was carried out as a cross sectional study of 1020
randomly selected children 9 and 15 years of age. Physical
measurements were blood pressure (BP), sum of four skinfolds
and cardiorespiratory fitness. Biochemical measurements were
serum total cholesterol (TC), high density lipoprotein cholesterol (HDL), triglyceride, glucose and insulin.
Cardiorespiratory fitness was assessed by a maximal cycle
ergometer test. A subject was defined as having a risk factor if
he/she belonged to the upper quartile of risk within age and
gender group for that risk factor. Clustering was analysed in
relation to being at risk in a) three or more and b) four or
more of five possible risk factors (TC:HDL ratio, insulin:glucose ratio, triglyceride, systolic BP and sum of four skinfolds).
All analyses were performed using the Statistical Package for
the Social Sciences (SPSS) version 11.
Results
Physical fitness was weakly related to single CVD risk factors
except sum of skin folds where the relationship was strong.
Low fitness increased the risk of having three or more CVD
risk factors. Compared to children in the most fit quartile, the
subsequent quartiles had odds ratios (OR’s) of 3.6 (95% CI:
0.7-17.4), 3.6 (95% CI: 0.7-17.7) and 24.1 (95% CI: 5.7101.1). Four or five risk factors were observed to be extremely
rare among children in the high fit quartile - only two subjects
in this quartile had 4 or more risk factors. Therefore, in order
to obtain smaller confidence intervals, the analysis were repeated defining cases as those children having three or more risk
factors. In this analysis, the odds ratios, using the upper quartile of fitness as reference, were 1.9 (95% CI: 0.8-4.1), 3.0
(95% CI: 1.4-6.3) and 11.4 (95% CI: 5.7-22.9) respectively,
with OR using the upper quartile of fitness as reference of 1.9
(95% CI: 0.8-4.1), 3.0 (95% CI: 1.4-6.3) and 11.4 (95% CI:
5.7-22.9), respectively. Using the criterion of four or more risk
factors, an OR of 24.1 (95% CI 5.7 – 101.1) was found.
55
revista
19.9.03
0:50
Página 56
Discussion/Conclusion
The main strength of this study is the large number of randomly sampled children, who are representative of the general
Danish population for these ages. The sample size makes it
possible to analyse clustering of risk factors, which is present
in a small proportion of the population.
This study of children and adolescents confirms the findings
from studies on adults that physical fitness is associated with
individual CVD risk factors, but associations are weak except
for the relationship with fatness, which is strong. Further, CVD
risk factors cluster strongly in individuals with low fitness. The
rationale for selecting the five risk factors reported above to
assess clustering was that they are all recognised elements of
the metabolic syndrome. It is plausible that insulin insensitivity may be the common aetiology causing these risk factors to
cluster (2).
It is noteworthy that the association between physical fitness
and clustering of risk factors in our study is even stronger than
the association between fitness and CVD mortality in adults. It
should also be noted that the physical fitness level of the children and adolescents in the lowest quartile of fitness was as
low as the fitness levels of blind children and adolescents, who
because of their handicap engage in very little vigorous physical activity.
Because individual risk factors track from childhood into adulthood, the childhood period should be considered a vital period
for primary CVD prevention programmes, of which the promotion of physical fitness should be an important element.
References
1. Rauramaa R, Rankinen T, Tuomainen P, Vaisanen S, Mercuri M
(1995). Inverse relationship between cardiorespiratory fitness and caritid atherosclerosis. Atherosclerosis 112: 213-221
2. Reaven GM, Lithell H, Landsberg L (1996). Hypertension and associated metabolic abnormalities - the role of insulin resistance and the
sympathoadrenal system. New Engl J Med 334: 374-381
THE RELATIONSHIP BETWEEN PHYSICAL ACTIVITY
AND DIETARY INTAKE DURING ADOLESCENCE
AND ARTERIAL PROPERTIES AT THE AGE OF 36 YEARS
Twisk Jos1,2, van Koolwijk Leonieke1, Ferreira Isabel1,
van Mechelen Willem1,3, Kemper Han1
1
Institute for Research in Extramural Medicine, VU University
Medical Centre, Amsterdam, The Netherlands
2 Department of Clinical Epidemiology and Biostatistics, VU
University Medical Centre, Amsterdam, The Netherlands
3 Deparment of Social Medicine, VU University Medical Centre,
Amsterdam, The Netherlands
strategy with respect to the prevention of CVD at adult age
could be a change towards a healthy lifestyle during youth.
Physical activity and dietary intake are recognised as important
components of such a healthy lifestyle. For these components,
especially the adolescent period seems to be important.
However, little is known to what extent adolescent lifestyle is
related to arterial wall thickness and stiffness, i.e. two major
contributory factors to cardiovascular morbidity and mortality.
The purpose of this study was to investigate the relationship
between physical activity and dietary intake during adolescence
and wall thickness of the carotid and stiffness of the carotid
and the femoral artery later in life, i.e. at the age of 36 years.
Methods
In the Amsterdam Growth and Health Longitudinal Study
(AGHLS), over a period of 25 years, nine repeated measurements were carried out. During the first four years of the study
(starting at 12/13 years of age) four consecutive measurements
were carried out. Between the age of 21 and 32 years four
measurements were performed, and in 2000 the subjects were
measured for the ninth time at the age of 36 years. Physical
activity was measured by an extensive interview and expressed
in METs. The total activity score was calculated by using duration, intensity and frequency of all physical activities performed
one month prior to the interview. Dietary intake was measured
by a crosscheck dietary history over the last three months prior
to the measurement. In the analyses a so-called ‘dietary health
score’ was used in which the intake of fruits, vegetables, fish
and low-fat dairy products were valued positively and in which
the intake of meat and snacks were valued negatively. The
dietary ‘health score’ ranged between 0 (indicating that the
subject was in none of the ‘healthy’ tertiles for all food groups)
to 6 (indicating that the subject was in the ‘healthy’ tertile for
all food groups). Both physical activity and dietary intake were
measured 3 to 4 times during the adolescent period (i.e.
between 12 and 16 years of age) and the average was used in
the analyses. Regarding the arterial properties measured at 36
years of age, for both the carotid and the femoral artery, compliance and distensibility of the vessel wall were measured
with ultrasound. For the carotid artery also intima media thickness and Young’s elastic modulus were measured (also with
ultrasound). Linear regression analyses were used to analyse
the relationships and the analyses were performed on a population of 75 males and 79 females.
Results
The results of the linear regression analyses are shown in Table 1:
Keywords: physical activity, dietary intake, arterial properties
Introduction
One of the most important chronic diseases in the developed
countries is cardiovascular disease (CVD). Even though the
clinical symptoms of CVD do not become apparent until much
later in life, it is known that the origin of CVD lies in early
childhood. It is therefore often argued that prevention of CVD
has to start as early in life as possible. A possible preventive
56
Table 1: Standardised regression coefficient and p-values
of the linear regression analyses regarding the relationship
between physical activity and dietary intake during adolescence
and thickness and stiffness of the carotid and femoral artery.
revista
19.9.03
0:50
Página 57
Results of the analyses showed that physical activity during
adolescence was not associated to large arterial properties at the
age of 36 years. On the other hand, for males, a ‘healthy diet’
during adolescence was associated to healthy distensibility and
compliance of the carotid artery (standardised regression coefficients 0.35 [p<0.01] and 0.29 [p<0.01] respectively). Besides
this, for males also an inverse relationship was found with
Young’s elastic modulus (standardised regression coefficient 0.27 [p<0.02]). For females and with arterial properties of the
femoral artery no significant associations were found (besides
the unexpected inverse relationship between a ‘healthy diet’ and
distensibility of the femoral artery for females).
It can be concluded that for males a ‘healthy diet’ during adolescence was related to ‘healthy’ arterial properties of the
carotid artery at adult age. Physical activity during adolescence
was not related to large arterial properties at adult age.
References
Kemper HCG (ed.) (1995). HK Sports Science Monograph Series,
Human Kinetics Publishers, Volume 6
Ferreira I, JW Twisk, W Van Mechelen, HC Kemper, and CD
Stehouwer (2002). Eur J Clin Invest 32: 723-731
BLOOD PRESSURE MEASUREMENT DURING TREADMILL EXERCISE
— A CHALLENGE
Instebø Arne1, Helgheim Vegard1, Røksund Ola Drange1,
Hirth Asle1,2* Greve Gottfried1,2
Departments of 1Paediatrics and 2Heart Disease Haukeland
University Hospital, Bergen, Norway
Keywords: oxygen consumption, anaerobic threshold, repeatability
Introduction
Exercise testing is valuable to determine the adequacy of cardiac and pulmonary function. This kind of physiological stress
can both determine exercise capacity, and elicit exercise limiting cardiovascular abnormalities or pulmonary diseases. At
“The Heart and Lung Laboratory” Department of Paediatrics,
Haukeland University Hospital, we use treadmill testing to
reveal exercise limiting disease and to monitor patients over
time. When monitoring patients it is important to evaluate the
results by parameters that are reproducible. The test to test
variation must also be considered. By examining blood pressure, heart rate and oxygen consumption, we can follow
changes due to illness. Maximal oxygen consumption (VO2max)
is a highly reproducible parameter. It depends almost exclusively on the cardiovascular system. Oxygen consumption during sub-maximal exercise on ergometer cycle is less reproducible than at maximal exercise (Wergel-Kolmert et al. 2002).
Even though anaerobic threshold is measured at one point, we
know that transition from aerobic to anaerobic work is gradual.
In an incremental exercise test there will be two ventilatory
breakpoints, between which there is a gradual transition from
aerobic to anaerobic activity, also called isocapnic buffer phase
(Wasserman et al. 1994). The phase after the second ventilatory breakpoint is called hypocapnic hyperventilation, since
hyperventilation leads to low expiratory concentrations of CO2.
According to this we can divide an incrementing exercise test
into aerobic phase, isocapnic buffer phase and hypocapnic
hyperventilation phase. When examining oxygen consumption
in each phase, we find differences due to exercise status or disease. Repeatability for these phases has not been evaluated.
Blood pressure during exercise can reveal exercise induced
hypertension or blood pressure fall, which can indicate or confirm exercise limiting heart or lung disease. By following blood
pressure through an incrementing treadmill test, we can study
each patient’s ability to perform physical activity. Systolic blood
pressure rises with increasing activity as a result of increasing
cardiac output, whereas diastolic pressure usually remains
about the same or is moderately reduced (Fletcher et al. 2001).
Association for the Advancement of Medical Instrumentation
and British Hypertension Society have prepared guidelines for
standardising devices to measure blood pressure during resting
conditions. However, there are no standards for blood pressure
measurements during exercise. We studied repeatability of
automated sphygmomanometry during treadmill exercise for
better understanding of how to interpret blood pressure readings during exercise.
Methods
Ten healthy and non-smoking men (age: 26.1 ± 3.6 yrs, height:
179.6 ± 6.4 cm, weight: 76.6 ± 9.7 kg) were studied over a
period of 2 months. Informed consent was obtained from all
participants. The study complies with Norwegian laws. The
Regional Ethical Committee has approved the project. Each
subject performed two identical exercise tests on a treadmill
(Woodway Ergo ELG 70, Weil am Rhein, Germany), according
to a modified Bruce protocol. The two tests were to be separated by minimum 48 hours and maximum 2 weeks, and were
done at the same time of the day. The subjects did not eat or
drink coffee the last twelve hours before each test. A Medical
Graphics cardiopulmonary exercise system (Sensormedics Vmax29, Yorba Linda, Savi Ranch Parkway, CA) was used, and
expired gas was sampled through a Rudolph mask. The expiratory gas was collected and conveyed to a spirometer and to
oxygen and carbon dioxide detectors. The measurement system was carefully calibrated, in accordance to the
Sensormedics’ standard, daily and before each test. The oxygen
consumption, carbon dioxide (CO2) production and ventilation
were measured continuously breath-by-breath. Mean respiratory values of 30 seconds were used in all calculations. Serum
lactate concentration was measured (Laktate pro, Arkray,
Shiga, Japan) every 90 seconds. Blood pressure in the right arm
was measured before, after and at 4 minutes intervals during
the exercise test (Paramed Technology Inc. Model 9350 Blood
Pressure Monitor). The blood pressure monitor uses an automated pressure cuff with pressure sensor. Heart rate and ECG
were registered by “Sensormedics” 12 lead system, and “Polar
Accurex Plus Sport-tester” (Finland) was used to confirm heart
rate. VO2max was defined as the highest oxygen consumption
measured during exercise. We assumed that VO2max was
achieved when two of the four following criteria were met:
subjectively felt exhaustion, the presence of an oxygen consumption plateau despite increasing exercise intensity, attainment of 95% of the age-predicted maximal heart rate and a respiratory exchange ratio equal to or greater than 1.05, during
the final increment of the exercise test. Ventilatory anaerobic
threshold is defined as the oxygen consumption at anaerobic
57
revista
19.9.03
0:50
Página 58
threshold defined by the v-slope method (Beaver et al. 1986).
Lactic acid threshold is defined as the oxygen consumption
when blood lactate concentration increased above baseline
level. The onset of blood lactic acid accumulation is defined as
the oxygen consumption when lactic acid concentration
reached 4 mmol/liter. Onset of isocapnic buffering (Wasserman
et al. 1994) was oxygen consumption when end tidal oxygen
pressure and ventilatory oxygen equivalent (ventilation/oxygen
consumption) began to increase and indicated the first ventilatory breakpoint. The onset of hypocapnic hyperventilation
(Wasserman et al. 1994) is defined as the oxygen consumption
when end tidal CO2 pressure began to decrease and ventilatory
CO2 equivalent (ventilation/CO2 production) began to increase
and indicated the second ventilatory breakpoint. Aerobic phase
is defined as the oxygen consumption between zero and onset
of isocapnic buffering. Isocapnic buffer phase is the oxygen
consumption between onset of isocapnic buffering and onset of
hypocapnic hyperventilation. Hypocapnic hyperventilation
phase is the oxygen consumption between onset of hypocapnic
hyperventilation and VO2max. All data are expressed as means
±SD unless otherwise indicated. Repeatability between two
measurements was evaluated by the coefficient of repeatability
(COR), calculated as 2⋅SD of the difference between the two
measurements and expressed as a percentage of the measurements’ mean (COR% = 2⋅SD/mean). Spearman’s rank correlation coefficient (rs) was used to study the relation between
VO2max and sub-maximal values. A standard two-sided t-test
for comparison of two groups of data with different standard
deviations is used to describe significance. A p-value < 0.05
was considered statistically significant.
Results
VO2max (test1: 56±10 ml⋅kg-1min-1, test2: 57±10 ml⋅kg-1min-1)
has excellent repeatability (COR%=8,5). Ventilatory anaerobic
threshold (test1: 31±6 ml⋅kg-1min-1, test2: 31±7 ml⋅kg-1min-1)
is achieved just before lactic acid threshold (test1: 33±6 ml⋅kg1min-1, test2: 36±6 ml⋅kg-1min-1) and approximately in the middle of the isocapnic buffer phase. Repeatability for ventilatory
anaerobic threshold (COR%=11,0) is better than for lactic acid
threshold (COR%=32,0). Onset of blood lactic acid accumulation (test1: 40,7±9 ml⋅kg-1min-1, test2: 46,1±10 ml⋅kg-1min-1)
seems to express onset of hypocapnic hyperventilation (test1:
44±8 ml⋅kg-1min-1, test2: 44±8 ml⋅kg-1min-1). Repeatability for
oxygen consumption at onset of blood lactic acid accumulation
is COR%=30,8. Repeatability of oxygen consumption during
aerobic phase, isocapnic buffer phase and hypocapnic hyperventilation phase is COR%=19.0, COR%=18.4 and
COR%=40.7 respectively. The best predictors of high VO2max
was ventilatory anaerobic threshold (test1: r=0.89, test2:
r=0.90), isocapnic buffer phase (test1: r=0.89, test2: r=0.86)
and onset of blood lactic acid accumulation (test1: r=0.85,
test2: r=0.97), all are significantly correlated. We obtained 90
of 140 (64%) systolic and 99 of 140 (71%) diastolic blood
pressure measurements. Mean values for all systolic blood
pressure measurements were 150±22 mmHg during test 1 and
153±24 mmHg during test 2, diastolic values were 84±14
mmHg and 83±11 mmHg. Systolic blood pressure increases
with exercise time and reaches a peak of 174±13 mmHg at a
heart rate of 160 bpm (82% of heart rate at VO2max). Diastolic
blood pressure seems to remain constant throughout the exercise test. Systolic blood pressure measurements are more
repeatable (COR%=28.1) than diastolic measurements
58
(COR%=37.8). It seems like lack of blood pressure repeatability is the same over the whole blood pressure range.
Our study confirms that VO2max obtained by an incrementing
treadmill test, is highly repeatable (COR%=8,5) and seem to
be more repeatable than obtained by cycle (COR%=11,
Wergel-Kolmert et al. 2002). Sub-maximal values indicate that
ventilatory anaerobic threshold is achieved just before lactic
acid threshold. They probably represent the same incident in
the middle of the isocapnic buffer phase. This is a logical result
since isocapnic buffering represents a gradual transition from
aerobic to anaerobic exercise. However, ventilatory anaerobic
threshold (COR=11.0) is more repeatable as indicator of
anaerobic threshold than lactic acid threshold (COR=32.0).
The difference in repeatability is probably mostly due to the
difference in recording frequency, where lactic acid is recorded
every 90 seconds while gas exchange values are recorded as
mean over 30 seconds. Because the onset of blood lactic acid
accumulation is recorded at a higher lactic acid concentration
than lactic acid threshold, it is achieved at higher oxygen consumption. It seems to express onset of hypocapnic hyperventilation, which indicates that exercise intensity above this
threshold will lead to increased blood acidity and rapid exhaustion. Like ventilatory anaerobic threshold, lactic acid threshold
and onset of blood lactic acid accumulation are good predictors
of VO2max and confirm that anaerobic thresholds achieved at
high oxygen consumption predict high VO2max. We can divide
the oxygen consumption during an incrementing exercise test
into an aerobic phase, an isocapnic buffer phase and a hypocapnic hyperventilation phase. When examining oxygen consumption in each phase, we find differences due to exercise status or
decease. Athletes have a wide isocapnic buffer phase and high
VO2max due to increased CO2 buffer capacity in the muscle. The
importance for physical fitness of well-developed CO2 buffers
in muscles, are emphasised through the good correlation
between isocapnic buffer phase and VO2max (test1: r=0.89,
test2: r=0.86). Unpublished data in our laboratory reports a
good correlation between aerobic phase and VO2max for patients
with mild hypertension operated for coarctation of the aorta,
due to disturbed blood pressure regulation and high blood perfusion in muscles. The healthy participants in the present
study have no such correlation between aerobic phase and
VO2max. Oxygen consumption during aerobic phase
(COR=19,0) and isocapnic buffer phase (COR=18,4) are more
repeatable than hypocapnic hyperventilation phase
(COR=42,5), probably mostly because oxygen consumption
increases least in the last phase giving variations more influence. Blood pressure measurements during exercise are difficult to obtain. There are no validation standards for blood pressure measurements during exercise, and standards recommended for validation of blood pressure measured at rest are
inappropriate for exercise conditions. One advantage of automated sphygmomanometry is that inter-technician variability
can be avoided, but still noise and movement artefacts, during
exercise often compromise the accuracy of sphygmomanometry. The accuracy has in previous studies, mainly been evaluated by comparison to direct intra-arterial measurements or
manually auscultation. The difference between sphygmomanometric and intra-arterial blood pressure is however depending
on exercise intensity, choice of artery and normal blood pressure fluctuations. It is therefore useful to look at repeatability
revista
19.9.03
0:50
Página 59
of sphygmanometric blood pressures without comparison to
direct intra-arterial mesurement. We obtained 90 of 140 (64%)
systolic and 99 of 140 (71%) diastolic blood pressure measurements. This illustrates the difficulties in the method and in
many cases one exercise test is not sufficient to obtain a clear
picture of blood pressure response. Mean values indicate that
systolic blood pressure increases with exercise time, reaches a
peak at 12 minutes at a heart rate of 160 bpm (82% of heart
rate at VO2max). Diastolic blood pressure seems to remain constant throughout the exercise test. Systolic blood pressure
(COR%=28.1) was more repeatable than diastolic
(COR%=37.8). Repeatabilty for these measurements are less
than for ambulatory blood pressure measurements (systolic
COR%=21,5 and diastolic COR%=22,4, Roy Olsen et al.
2002). This is not surprising since persons undergoing ambulatory measurements are told to stop activity while blood pressure is measured. Noise interference during exercise often
makes it hard to trust an obtained reading and this influences
repeatability. It is however not certain that the difference in
repeatability between ambulatory and exercise measurements
is only due to movement artefacts since the lack of repeatability during exercise seems to be the same over the whole blood
pressure range. Natural variation in a person’s blood pressure
is higher while exercising, and this can therefore contribute to
a difference in blood pressure responses between two tests.
Despite the mentioned difficulties in measuring blood pressure
during exercise, we are convinced that the method can reveal
significant changes in blood pressure response. When dealing
with patients it is mandatory to discover both exercise induced
hypertension and blood pressure fall. It is often favourable to
exercise patients on a treadmill since they then recruit large
muscle group making them able to achieve higher oxygen consumption without stopping due to lactic acid accumulation in
smaller muscle groups. In our experience it is easier to motivate small children for treadmill than for cycle exercise.
References
Beaver WL, Wasserman K, Whipp BJ. (1986). J Appl Physiol. 60(6)
Jun:2020-7
Olsen R, Amlie A, Omvik P (2002). Blood Press Monit. 7:149-156
Wasserman K, Beaver WL, Whipp BJ (1990). Circulation 81(1
Suppl) Jan:II14-30. Review
Wergel-Kolmert U, Wisen A, Wohlfart B (2002). Clin Physiol Funct
Imaging,;22(4)Jul: 261-5
EXERCISE TESTING AFTER REPAIR OF COARCTATION OF THE AORTA
Instebø Arne1, Norgård Gunnar1, Helgheim Vegard1, Røksund
Ola Drange1, Segadal Leidulf 2, * Greve Gottfried1,2
Departments of 1Paediatrics and 2Heart Disease,
Haukeland University Hospital, Bergen, Norway
Keywords: blood pressure, oxygen consumption, anaerobic threshold
Introduction
Coarctation of the aorta is an obstruction of the aorta, usually
where the arch continues into the descending aorta at the site
of the arterial duct. It represents 5 to 7 % of the congenital cardiovascular malformations. The degree of stenosis may vary
from a mild coarctation without significant haemodynamic
effects to an interrupted aortic arch with devastating effects on
the circulation when the arterial duct closes. The origin of the
left subclavian artery is affected in some patients. There has
been reported a mortality rate of 0 to 20 % in coarctation
patients (Thu et al.1999), which depends on several factors
such as: severity of obstruction, heart failure before surgery,
age at surgery, surgical technique applied and the complexity of
associated heart malformations. The most common complications after surgery are abnormal blood pressure response during physical exercise, restenosis, hypertension, and aortic valve
stenosis mostly in patients with a bicuspid aortic valve and
aneurysms of the aorta. Even without recoarctation after surgery, these patients often have hypertension at rest or an
abnormal blood pressure response during exercise, leading to
premature death. Some patients need reoperation or balloon
dilatation because of a rest- or recoarctation. There is dispute
regarding what resting systolic blood pressure difference
between right arm and leg, require intervention. In this study
we have investigated how the resting systolic blood pressure
difference between right arm and leg influences the resting systolic blood pressure, maximal systolic blood pressure during
exercise, systolic blood pressure difference between right arm
and leg immediately after exercise, and transition from aerobic
to anaerobic exercise. Our hypothesis is that exercise testing is
necessary to reveal exercise induced hypertension, that there is
no relation between systolic blood pressure at rest and during
exercise, and that increased blood pressure has an effect on the
transition from aerobic to anaerobic metabolism.
Methods
The inclusion criteria for the 41 subjects studied during a 19
months period, were patients aged 15–40 years with coarctation of the aorta repaired at Haukeland University Hospital,
Bergen, Norway in the period 1975-96. We divided the
patients in three groups depending on their resting supine systolic blood pressure difference between right arm and thigh.
Group 1 had a systolic blood pressure difference between right
arm and leg less than 1 mmHg, group 2 had a difference
between 1 and 20 mmHg and group 3 had a difference above
20 mmHg. The groups were comparable. The patients were
exercised on a treadmill (Woodway Ergo ELG 70, Weil am
Rhein, Germany) according to a modified Bruce protocol. A
Medical Graphics cardiopulmonary exercise system
(Sensormedics V-max29, Yorba Linda, Savi Ranch Parkway,
CA) was used, and expired gas was sampled through a
Rudolph mask. The expiratory gas was collected and conveyed
to a spirometer and to oxygen and carbon dioxide detectors.
The measurement system was carefully calibrated in accordance to the Sensormedics recommendations daily and before
each test. Oxygen consumption, carbon dioxide production and
ventilation were measured continuously breath by breath.
Mean respiratory values of 30-seconds were used for all calculations. Blood pressure was measured in the right arm and leg
simultaneously before and after exercise. For the calculations
we used the mean of three repeated supine measurements in
every patient before the exercise test. We used the first supine
blood pressure measurement within the first 2 minutes after
the exercise test was ended. The blood pressure in the right
arm was measured at 4-min. intervals during the exercise test.
Paramed Technology Inc. Model 9350 Blood Pressure Monitor
(340 Pioneer Way, Mountain view, CA, US) was used for blood
59
revista
19.9.03
0:50
Página 60
pressure recordings in the arm. This instrument has an automated pressure cuff and a pressure sensor. Dinamap XL Vital
Signs Monitor (Critikon Inc., Arlington, TX, US) was used for
recordings in the leg. This instrument has automated pressure
cuffs and is an oscillometric blood pressure monitor. Heart rate
was measured with a Polar Accurex Plus Sport-tester (Fin90440, Kempele, Finland), and ECG was registered using
Sensormedics 4-lead system. Arterial oxygen saturation was
measured using Sensormedics’ pulsoximetry on the index finger of the patients’ left hand. Maximal oxygen consumption
was defined as the highest oxygen consumption measured during exercise. We assumed that maximal oxygen consumption
was achieved when two of four criteria were met. The criteria
are subjectively felt exhaustion, the presence of an oxygen consumption plateau despite increasing exercise intensity, attainment of 95% of the age-predicted maximal heart rate and a respiratory exchange ratio equal to or greater than 1.05, during
the final increment of the exercise test. 12 of 41 patients were
defined by the exhaustion criterion. The onset of isocapnic
buffering (Wasserman et al. 1994) was defined as the oxygen
consumption when both the end tidal oxygen pressure and the
ventilatory oxygen equivalent (ventilation/oxygen consumption) began to increase. The onset of hypocapnic hyperventilation (Wasserman et al. 1994) was the defined as the oxygen
consumption when the end tidal carbon dioxide pressure began
to decrease and the ventilatory carbon dioxide equivalent (ventilation/carbon dioxide production) began to increase. The ventilatory anaerobic threshold was defined by the v-slope method
(Beaver et al. 1986). The aerobic phase was defined as oxygen
consumption between zero and onset of isocapnic buffering.
Isocapnic buffering phase was defined as oxygen consumption
between onset of isocapnic buffering and onset of hypocapnic
hyperventilation. Hypocapnic hyperventilation phase was
defined as oxygen consumption between threshold for onset of
hypocapnic hyperventilation and maximal oxygen consumption. All data are expressed as means ± SD unless otherwise
indicated. The Pearson correlation coefficient and linear regression analysis describe the relationship between different
parameters when appropriate. A standard two-sided t-test for
comparison of two groups of data with different standard deviations is used to describe significance. A p-value < 0.05 is considered statistically significant.
Results
We find significantly higher resting systolic blood pressure for
group 2 compared to group 1 (p<0.0001), and significantly
higher resting systolic blood pressure for group 3 compared to
group 2 (p<0.01). Group 3 compared to group 1, has significantly higher systolic blood pressure difference between right
arm and leg immediately after exercise (p<0.02). Maximal systolic blood pressure during exercise is not significantly different between the groups, although higher in group 3. There is a
good correlation between resting systolic blood pressure difference between right arm and leg and resting systolic blood pressure (r =0.81, p<0.01). In all groups there was a good correlation between ventilatory anaerobic threshold and maximal oxygen consumption (group 1: r=0.76, p<0.01; group 2: r=0.88,
p<0.01; group 3: r=0.78, p<0.01). Oxygen consumption (in
percent of maximal oxygen consumption) at this threshold was
not significantly different between the groups: 49±14, 47±8 and
49±9 for groups 1, 2 and 3, respectively. The aerobic phase is
significantly wider in group 2 compared to group 1 (p<0.03).
60
There is a tendency to narrower isocapnic buffering zone
(p<0.2) and increased maximal oxygen consumption (p<0.2)
in group 2 compared to group 1, and a wider hypocapnic
hyperventilation zone in group 3 compared to group 1 (p<0.1).
The maximal oxygen consumption is reduced in group 3 compared to group 2, although not significantly. Males are however
over-represented in group 3 compared to group 1 and 2, which
probably disturbs a significant reduction in maximal oxygen
consumption. Group 1 has significant relation between maximal oxygen consumption and isocapnic buffering phase.
Groups 2 and 3 have significant relations between maximal
oxygen consumption and aerobic phase. All groups have significant relations between maximal oxygen consumption and
hypocapnic hyperventilation phase.
Discussion/conclusion
Our study has confirmed that hypertension at rest or in
response to exercise remains a considerable problem in
patients after surgical repair of coarctation of the aorta. We
find that there is a good correlation between the resting systolic blood pressure difference between right arm and leg and
the resting systolic blood pressure (r =0.81, p<0.01). Patients
in group 1 have normal systolic blood pressure, group 2 has
mild hypertension and group 3 has hypertension. We find that
neither the resting systolic blood pressure, nor the resting systolic blood pressure difference between right arm and leg, are
good indicators for either maximal systolic blood pressure or
systolic blood pressure difference between right arm and leg
immediately after exercise. Thus, it is important to measure
blood pressure during exercise to reveal exercise induced
hypertension or increased blood pressure difference between
right arm and leg. Blood pressure in the arm cannot easily be
measured during exercise due to movement artefacts. 33 of 41
patients in this study could be measured during exercise. It has
been questioned if the blood pressure difference between right
arm and leg immediately after exercise is accurate enough to
serve as an indicator for exercise induced blood pressure difference at maximal exercise (Engvall et al. 1995). The measurements are most difficult to obtain in the leg. We tried to obtain
these in the leg as soon as possible after exercise, and succeeded in supine recordings within 2 minutes after maximal exercise in 35 of the 41 patients. Because of high resting systolic
blood pressure for group 3, we are convinced that a resting systolic blood pressure difference between right arm and leg above
20 mmHg (group 3) should serve as an indication for catheterisation and eventually intervention. This is also the indication
for intervention stated in a resent scientific statement from the
American Heart Association (Allen et al. 1998). Group 2
patients should be evaluated for catheterisation in light of
hypertension during exercise and echo-Doppler or MRI detected residual coarctation. We recommend regular follow up of
group 1 patients, because patients often develop hypertension
or abnormal blood pressure response to exercise with prolonged follow up time (Clarkson et al. 1983). In the present
study we wanted to illustrate the impact of blood pressure on
transition from aerobic to anaerobic exercise. It has recently
been described an excessive dependence on anaerobic metabolism during exercise in patients with repair of the aorta and
hypertension (Rhodes et al. 1997). Their conclusion is partly
confirmed in our material where we have found significant
relations between maximal oxygen consumption and hypocapnic hyperventilation phase in all three groups. Ventilatory
revista
19.9.03
0:50
Página 61
anaerobic threshold is correlated to maximal oxygen consumption in all three groups, and seems to be a good parameter for
evaluating the anaerobic threshold in these patients. The ventilatory anaerobic threshold can however not differentiate the
degree of illness. An interesting finding is that group 2 patients
have a significantly wider aerobic phase and higher maximal
oxygen consumption compared to group 1 and the wide aerobic phase predicts the higher maximal oxygen consumption.
This is a striking difference compared to group 1 where wide
isocapnic buffering phase predicts higher maximal oxygen consumption, which is normal for healthy persons. A slight
increased blood pressure in group 2 seems to help in achieving
higher maximal oxygen consumption. The reason for this could
be a disturbance of the blood pressure regulation due to
anatomical and physiological changes. Blood pressure overcompensates the peripheral resistance securing a better peripheral
blood flow. Overcompensation of a slight increase in aortic
resistance can contribute to a slight cardiac hypertrophy,
increasing stroke volume and muscle-perfusion, as seen in athletes. A higher blood flow in the muscle facilitates longer duration of aerobic work and this increases the exercise capacity.
Isocapnic buffering phase is however decreased, opposed to
athletes, and thereby limiting a great increase in exercise
capacity. When the resting systolic blood pressure difference
between right arm and leg becomes too high, as it does for
group 3 patients, there will be a large load on the heart and
hypertensive effects on the heart and peripheral circulation will
develop. This leads to a narrower aerobic phase. Maximal oxygen consumption is reduced and isocapnic buffering zone does
not predict maximal oxygen consumption. It is reasonable to
think that an even higher resting systolic blood pressure difference between right arm and leg will induce an even higher
restrain on the maximal oxygen consumption.
References
Allen HD, Beekman RH, Garson A Jr. Hijazi ZM, Mullins C,
O’Laughlin, Taubert KA (1998). Circulation : 97:609-25
Beaver WL, Wasserman K, Whipp BJ (1986). J Appl Physiol.
Jun;60(6):2020-7
Clarkson PM, Nicholson MR, Barratt-Boyes BG, Neutze JM, Whitlock
RM (1983). Am J Cardiol. May 15;51(9):1481-8
Engvall J, Sonnhag C, Nylander E, Stenport G, Karlsson E, Wranne B
(1995). Br Heart J 73 : 270-6
Rhodes J, Geggel RL, Marx GR, Bevilacqua L, Dambach YB, Hijazi
ZM (1997). J Pediatr 131 : 210-4
Thu K, Segadal L, Kvitting P, Greve G (1999). Tidsskr Nor Laegeforen
119 : 2162-5
Wasserman K, Beaver WL, Whipp BJ (1990). Circulation. Jan;81(1
Suppl):II14-30. Review
ARRHYTHMIAS AND PHYSICAL ACTIVITY IN CHILDREN
Giordano Ugo1, Nigro Antonia2, Crosio Gaia1, Turchetta Attilio1,
Calzolari Flaminia1, Calzolari Armando1
1
Sports Medicine Unit- Department of Pediatrics - Bambino Gesù
Children’s Hospital, Rome, Italy
2 Scuola di specializzazione in Medicina dello Sport, Università di Tor
Vergata, Roma, Italy
Introduction
Hyperkinetic supraventricular and ventricular arrhythmias are
very frequent in the pediatric age and could be accompanied
and/or imply for acute or chronic heart diseases. To establish
the safety for the practice of physical activity it is necessary to
exclude the presence of heart diseases and then to evaluate,
non-invasively, the simple and/or the complex types.
Aim of the study: to evaluate the behaviour of the arrhythmias
(supraventricular and ventricular) towards the practice of physical activity in young athletes.
Material and Methods
45 pts have been examined in our laboratory to perform
Montoye Step Test to obtain the clearance for competitive
sports; 37 of them (26M; 11F) with a mean age of 10.5±3
years were selected for not-repetitive arrhythmias. All the 37
patients were asymptomatic with a negative familial and personal history of the cardiovascular apparatus. All patients
underwent to: 1) cardiovascular examination; 2) 2D-colordoppler echocardiography; 3) exercise testing on the treadmill;
4) 24 hours Holter monitoring.
The treadmill test was performed with Bruce protocol and
stopped for symptoms or muscular fatigue. We have analysed
time of exercise test in minutes, heart rate at rest and at peak of
exercise, blood pressure, measured with the Riva-Rocci method
with aneroid sphygomanometer, at rest and at peak of exercise
and behaviour of arrhytmia during the test and in the recovery.
In the 24-hours Holter monitoring we have valued the total
number of heart beats and the number of ectopic beats and so
we have calculated the percentile to do a comparison during
the follow-up.
Yearly follow-up was done for 4.1 ± 2 years.
Results
The cardiovascular examination and the echocardiogram were
negative; exercise testing on the treadmill showed a good exercise tolerance (>75% of the theoretical values) and a disappearance of the arrhythmia with the increase of the heart rate
in all patients. They were then divided in two classes in relation to the arrhythmia recorded at the 24 hours Holter monitoring: 1) 17 pts (13M; 4F) supraventricular premature complex; 2) 20 pts (13M; 7F) ventricular premature complex. We
observed: a) the disappearance of the arrhythmia in 47% of the
group 1 and in 40% of the group 2; b) a quantitative increase
of the arrhythmia in 12% of the group 1 and in 25% of the
group 2 (still not-repetitive); c) a reduction of the arrhythmia
in 41% of the group 1 and in 35% of the group 2.
Table 1. Follow-up of patients with arrhythmia.
Legend: A = patients with supraventricular premature complex;
B= patients with ventricular premature complex
Conclusions
In the presence of simple arrhythmia phenomena in normal
heart is possible to practice safely physical activity and competitive sports, performing yearly medical examinations of second
level (exercise testing and 24 hours Holter monitoring).
61
revista
19.9.03
0:50
Página 62
OSCILLATORY CHANGES OF OXYGEN UPTAKE DURING EXERCISE
IN CARDIOMYOPATHY: RELATIONSHIP WITH CLINICAL STATUS
Reybrouck Tony, Van Gesselen Steven, Weymans Maria,
Eyskens Benedicte, Mertens Luc, Gewillig Marc
Dept. Cardiac Rehabilitation, Dept. Rehabilitation Sciences KU
Leuven, University Hospital Gasthuisberg, Leuven, Belgium
Keywords: gas exchange, oxygen uptake kinetics, congenital heart
disease
Introduction
Oscillatory changes of the parameters of gas exchange during
exercise, have been reported in patients with congestive heart
failure and have been ascribed to hemodynamic dysfunction.
The aim of the present study was to analyse if this phenomenon is also observed in patients with cardiomyopathy (CMP).
Patients and Methods
14 children with CMP (7 with dilated DCMP, and 7 with hypertrophic HCMP) were selected for this study and underwent
exercise testing on a treadmill. At one minute intervals the
inclination of the treadmill was increased by 2 % while the
speed remained constant (5.6 km/h). These patients were compared to 29 normal controls (C) of the same age range, and 8
patients with a ventricular septal defect (VSD). Age at testing
averaged 9.6 ± 3.6 years for DCMP, 11.4 ± 3.3 years for
HCMP, 12.1 ± 2.4 years for VSD and 10.4 ± 2.9 years for normal controls (P >0.25). Gas exchange was measured breathby-breath by mass spectrometry. Variability of VO2 was determined as the difference between all single breaths during one
minute and the mean of those breaths, expressed as a percentage of the mean value for VO2 during that minute.
Results
Significantly (P<0.05) elevated values were found for oscillatory
changes in VO2, expressed as percent variability, in patients
with DCMP (varying from 7.3 to 11.7 %, for different levels of
inclination on the treadmill), when compared to HCMP(5.1 6.7 %), VSD (5.6 - 7.7 %) and C (5.8 - 7.4 %). No significant
difference was found between HCMP, VSD and C. Patients with
the highest value for variability of VO2 (exceeding the 95 % CL
of normal) were characterised by the lowest value for shortening fraction, determined on the echocardiogram (15-17%).
Conclusion
Increased oscillatory changes of VO2 during exercise in DCMP
correlate with hemodynamic dysfunction of the left ventricle
and suggests inadequate oxygen delivery to the exercising tissues.
METABOLIC COST AND PREFERRED STEP LENGTH
IN CHILDREN WITH SPASTIC CEREBRAL PALSY
Morgan Don1, Tseh Wayland2, Caputo Jennifer3, Keefer Daniel4,
Craig Ian5, Griffith Kelly5, Griffith Gareth5, Vint Peter5
1
62
Department of Kinesiology, Arizona State University, USA
2 Department of Health and Applied Human Sciences, The University
of North Carolina at Wilmington, USA
3 Department of Health, Physical Education, Recreation and Safety,
Middle Tennessee State University, USA
4 Department of Wellness and Sport Sciences,
Millersville University, USA
5 Department of Exercise and Sport Science, The University of North
Carolina at Greensboro, USA
Keywords: oxygen uptake, step length, cerebral palsy
Introduction
The aerobic demand (V02) required to walk or run at a given
submaximal speed is an important determinant of overall physical stress during locomotion. Results from a number of studies have shown that young and old adults typically adopt step
length patterns that minimize V02. Moreover, recent data suggest that energy use is optimized when able-bodied children
walk at preferred step lengths (PSL). The extent to which
metabolic cost is a self-optimizing feature of walking gait in
children with neuromuscular disease, however, remains
unclear. Against this backdrop, the purpose of our study was to
determine whether children with spastic cerebral palsy (CP)
select step length patterns that minimize the energy demands
of walking.
Methods
Three children with spastic hemiplegia and one child with
spastic diplegia (3 males, 1 female; age range = 5 to 12 years;
mean height = 138.1 + 21.5 cm; mean body mass = 40.0 +
24.3 kg) volunteered to participate in this study. Following initial exposure to treadmill walking (Session 1) and two additional testing bouts involving the acquisition of step length and
V02 data at a variety of walking speeds (Sessions 2 and 3), each
subject walked for five minutes at five randomly-assigned step
length conditions (PSL and -10%, -5%, +5%, and + 10% of leg
length (LL) from the PSL) at either 0.67 m•s-1 (n =2) or 0.89
m•s-1 (n = 2) (Session 4). Step length patterns were manipulated by having subjects match their stepping frequency to the
beat of an amplified audible signal generated by a computerreceiver interface. To reinforce the audible feedback, a computer screen provided a constantly-updated visual confirmation of
the accuracy of subjects’ attempts to attain desired step length
values. During the last two minutes of each step length condition, V02 was quantified by analyzing a 2-min expired gas sample collected in a meteorological balloon. Step length values
were obtained from a computer-footswitch interface operating
at a sampling frequency of 200 Hz. For each subject, a curve-fit
routine was used to generate polynomial equations best
expressing the association between step length and V02.
Results
Analysis of mean data revealed that V02 was lowest at the PSL
condition and rose in a curvilinear fashion as step length was
varied away from the PSL. At the shortest and longest step
length conditions, V02 increased by an average of 4.7 and 2.8
ml•kg-1•min-1, respectively, compared to the V02 measured at
the PSL. Examination of individual SL-V02 curves demonstrated that the mean absolute difference in relative step length
between the PSL and the energetically-optimal step length was
1.64% of LL. This deviation in relative SL corresponded to an
average V02 difference of 0.1 ml•kg-1•min-1.
revista
19.9.03
0:50
Página 63
Conclusion
Taken together, these preliminary data suggest that optimization of metabolic cost may be an important factor underlying
the choice of step length patterns during walking in children
with spastic cerebral palsy.
Acknowledgement
Supported by the National Institute of Child Health and
Human Development (HD 30749)
References
Morgan D (2000). In: Paediatric exercise science and medicine,
Oxford: Oxford University Press, 183-90
Morgan D, Tseh W, Caputo J, Craig I, Keefer D, Martin P (1999).
Ped Exer Sci 11:271-2
Morgan D, Martin P, Craib M, Caruso C, Clifton R, Hopewell R
(1994). J Appl Physiol 77:245-51.
Morgan D, Martin P (1986). Can J Appl Sport Sci 11:211-17.
FN (P=0.13) and GT (P=0.10) aBMD, and SOS (P=0.11) in
the JIA compared to the control group. In JIA subjects, aBMD
at all sites correlated positively (P<0.05) with physical activity
level, VO2peak, muscle strength and lean tissue mass (LTM),
and correlated negatively with joint count, ESR, pain and disease activity. Left SOS correlated positively with VO2peak and
LTM. Fourteen (58%) and 5 (20%) children had arthritis at the
left and right leg, respectively. Only one of them was treated by
corticosteroids. Mechanical loading applied on lower limbs may
be decreased in children with JIA, in relation with pain and
altered joint function, resulting in sub-optimal skeletal development at weight-bearing sites.
EFFECT OF DYNAMIC FOOT ORTHOTICS ON THE MOTOR SKILLS
OF CHILDREN WITH DEVELOPMENTAL DELAYS
Pitetti Kenneth H, Wondra Valarie C
Wichita State University, Wichita, Kansas, USA
BONE MINERAL DENSITY, PHYSICAL ACTIVITY, CALCIUM INTAKE
AND SEVERITY OF DISEASE IN CHILDREN WITH
JUVENILE IDIOPATHIC ARTHRITIS
Keller-Marchand Laetitia, Farpour-Lambert Nathalie J,
Hofer Michael, Rizzoli René, Hans Didier
Dept. of Pediatrics, University Hospital of Geneva, Switzerland
Keywords: juvenile idiopathic arthritis, bone mineral density, physical
activity
Juvenile Idiopathic Arthritis (JIA) is associated with low bone
mineral density and increased risk of osteoporosis later in life.
Physical activity during childhood is generally thought to have a
positive influence on skeletal development. The purpose of this
study was to determine areal bone mineral density (aBMD) and
ultrasound properties in children with JIA, and the relationships
to physical activity, aerobic fitness, muscle strength, calcium
intake, severity of disease, and corticosteroids.
This was a matched case-control study including two groups of
24 children aged 5 to 16 years (mean 10.13 +/- 2.70 SD): JIA
children and controls. Groups were matched for gender, age,
height, weight and pubertal stage. Primary measures included
total body (TB), lumbar spine (L2-4), left and right femoral
neck (FN) and greater trochanter (GT) aBMD by dual energyx-ray absorptiometry (DXA-Lunar Prodigy), and calcaneal
speed of sound (SOS) by quantitative ultrasound (Lunar
Achilles +). Other measures included physical activity level by
Modifiable Activity Questionnaire For Adolescents; VO2peak by
direct gas analysis during treadmill test; isokinetic knee flexion
and extension peak torque by dynamometer; body composition
by DXA; calcium intake by Food Frequency Questionnaire;
joint count; inflammation by erythrocyte sedimentation rate
(ESR) and serum C-reactive protein level; pain and disease
activity by Childhood Health Assessment Questionnaire.
There were no significant differences among groups for age,
height, weight, pubertal stage, body composition, physical
activity, VO2peak, muscle strength or calcium intake. Left FN
and GT aBMD, and left SOS were significantly lower in JIA,
compared to controls. There was a trend toward reduced right
Keywords: orthotics, developmental delays, motor skills
Introduction
Dynamic foot orthotic (DFO) is a general term that describes a
thinly layered shoe insert, which is placed in the shoes of children with motor delays in order to improve their balance and
motor capacities. DFOs can be used as a therapy device that
allows a child with developmental delays (e.g., children generally classified with developmental delays due to low muscle
tone, as in Down syndrome) to quickly (i.e., within days)
improve their postural control and balance. DFOs are designed
to give mild mechanical support and proprioceptive feedback to
children who have relatively normal strength and control of
their thigh and calf muscles, but poor control of their feet.
The type of DFO used in this study is specific for children
with “low tone” motor delays (i.e., as opposed to “high tone”
motor problems like spasticity seen in children with cerebral
palsy) and is clinically identified as a minimum control orthotic (MCO). MCOs are shoe inserts that contain one layer of
foam and a thin layer of polyethylene plastic which provides
greater structural support and is more resilient than a typical
foam shoe insert.
There have been descriptive and observational reports (i.e.,
anecdotal) on the benefits (e.g. improved balance and motor
skills) of MCOs in treating neurological and developmental disorders (Hylton, 1989), but there is a paucity of scientific data
regarding the effectiveness of MCOs. Therefore, the purpose of
this study is to add to the body of knowledge on MCOs and
their efficiacy as it relates to motor skills of children with various “low tone” developmental delays. Specifically, this study
examined the effects that a 2-month therapeutic program using
MCOs has on the locomotive scores of the Peabody
Developmental Motor Scales-II in children with developmental
motor delays.
Methods
Participants
Sixteen children (9 male, 7 female; age = 44.0+10.7 months)
with developmental delays (2 Down syndrome, 1 DandyWalker cyst, 1 cerebral palsy and 12 motor delayed) participat-
63
revista
19.9.03
0:50
Página 64
ed in this study. Classification of developmental delayed (DD)
was determined by a medical diagnosis from a physician using
appropriate diagnostic instruments and procedures.
Parental/guardian informed consents were obtained prior to
testing and approval for the study was obtained from the
University Institutional Review Board.
Instrument
The locomotion section of the Peabody Developmental Motor
Scales Test, 2nd edition (PDMS-2) was selected to evaluate the
participants motor abilities. The PDMS-2 was designed to
assess the gross and fine motor skills in children from birth to
six years of age. These motor abilities include, but are not limited to: standing, walking up and down stairs, walking fast,
walking backward, walking sideways, walking a line, jumping
up, jumping forward, jumping down, and running. The PDMS2 norms are based on scoring each item as 2 (the child performs the item according to the criteria specified for mastery),
1 (the child’s performance shows a clear resemblance to the
item mastery criteria but does not fully meet the criteria), and
0 (the child cannot or will not attempt the item, or the attempt
does not show that the skill is emerging). The PDMS-2 has
been shown to be a reliable and valid method of determining
motor skills in children 0 to six years of age (Aiken, 1994;
Nunnally & Bernstein, 1994; and Salvia & Ysseldyke, 1998).
Procedure
Two registered physical therapists (RPT) administered the
PDMS-2 to each participant. Each RPT scored the test separately, scores were then compared and discussed by the RPTs,
and the agreed score was used for data analysis. An initial test
was given without wearing the minimum control orthotic
(MCO). The child’s shoe was then fit with the MCO and the
participants wore the MCO for one week and were retested
with the MCO. The PDMS-2 was administered with and without MCO following two months of wearing the MCO, with at
least 24 hours between tests.
Data Analysis
Data were analyzed using SPSS (v. 10.1) and means and standard deviations were calculated for all variables. A paired t test
was performed to determine if differences existed in PDMS-2
raw scores (i.e., total points accumulated for each time) and
“motor age” equivalents of raw scores in months at initial testing and following 2 months of wearing the MCO. For all analysis, statistical significance was set at p<0.05.
Results
Results are shown in Table 1 (see below). Significantly higher
PDMS-2 raw and motor age equivalent scores were
seen while participants were wearing the MCO initially and
following 2 months.
Table 1. PDMS-2 Initial and 2 Month Test Scores
* = p<0.05
64
Discussion
Previous anecdotal reports have suggested that DFO improve
balance and motor skills in children with neurological and
developmental disorders (Hylton, 1989). However, there has
yet to be reported research data regarding the effectiveness of
DFO. In this study, a specific type of DFO, a minimum control
orthotic (MCO), was evaluated to determine their capacity in
improving the motor skills of children with various “low tone”
developmental delays. The results of this study suggest that
MCO do improve the motor capacities of these children.
References
Aiken LR. (1994). Psychological testing and assessment. Allyn &
Bacon, Neeham Heights, MA.
Hylton NM (1989). Journal of Prosthetics and Orthotics 2:40-53
Nunnally JC, & Bernstein IH (1994). Psychometric Theory (3rd ed.).
McGraw-Hill, New York
Salvia J, & Ysseldyke JE (1998). Assessment (7th ed). Houghton
Mifflin, Boston, MA
THE EFFICACY OF EXERCISE AS AN INTERVENTION
TO TREAT RECURRENT NON-SPECIFIC LOW-BACK PAIN
IN ADOLESCENTS AGED 14-16 YEARS
Jones Michelle, Stratton Gareth, Reilly Tom, Unnithan Vish
Edge Hill, England
Keywords: low-back pain, exercise, intervention
The aim of this investigation was to evaluate the efficacy of a
specific exercise programme as an intervention to treat recurrent non-specific low-back pain in adolescents. A randomised
controlled trial was conducted with an experimental group
(boys n=16, girls n=11, age 14.6(0.6) years) who participated
in a specific 8-week exercise programme and a matched control
group (boys n=16, girls n=11, age 14.6(0.5) years) who continued with normal daily activities. All subjects were identified
as having recurrent non-specific low-back pain via questionnaire and then interview. Pre and post intervention measures
of low-back pain status (pain severity and consequences reported in 1-week diaries), and health-related fitness were taken.
Two-way mixed ANOVA (independent variables: pre/post and
experimental/control) was conducted for each dependent variable, significance was set at P<0.05. In terms of the consequences and symptoms of low-back pain significant interaction
effects were identified for the number of pain occurrences
(F1,52=4.65, P=0.04), the perceived severity of the pain
(F1,52=71.74, P=0.00) and number of occasions missing sport
or physical activity due to the low-back pain (F1,52=16.85,
P=0.00). In each case significant improvement was noted in
the experimental group, effect sizes ranged from 0.27 to 1.47.
In terms of health related fitness, significant interaction effects
were identified for sit and reach performance (F1,52=103.25,
P=0.00), hip range of motion with the knee flexed
(F1,52=69.51, P=0.00) and extended (F1,52=52.04, P=0.00),
lumbar sagittal mobility (modified Schöber, F1,52=69.51,
P=0.00), lateral flexion of the spine (F1,52=29.03, P=0.00)
and number of sit-ups in 60 s (F1,52=45.25, P=0.00). In each
case significant improvement was noted in the experimental
revista
19.9.03
0:50
Página 65
group, effect sizes ranged from 0.52 to 0.91. No significant
interaction effects were identified for absence from school due
to low-back pain, body mass index, sum of four skinfolds or
grip strength. No significant relationship was identified
between the concurrent reduction in pain and improvement in
health related fitness, suggesting the change occurred through
alteration of pain perception and coping strategies. It was concluded that a specific exercise programme acted as an effective
short-term treatment strategy for recurrent non-specific lowback pain in adolescents. Further evaluation is required to
assess the long-term effectiveness.
basis, may lead to chronical back-pain with harmful consequences in their growth and motor development, in their
health and in the student’s well being.
References
Hong y, Li J, Wong A, Robinson P (2000). Ergonomics 43: 717-727.
Pascoe A, Pascoe E, Wang Y, Shim D, Kim C (1997). Ergonomics 40:
631-641.
Voll H, Klimt F (1977). Offentliche Gesundheitswesen 39:369-378.
PREDICTION OF PERCENT BODY FAT IN CHILDREN USING
SKINFOLDS FROM THE UPPER AND LOWER BODY
BIOMECHANICAL ANALYSIS OF ACUTE BACKPACK
LOAD CONSEQUENCES ON CHILDREN’S GAIT
Vilas-Boas J. Paulo, Carvalho Nuno, Lopes Tiago,
Gonçalves Pedro, Sousa Filipa
Eston Roger, Powell Clare
University of Wales, Bangor, Wales, UK
Keywords: body fat, skinfolds, thigh
Faculty of Sports Sciences and Physical Education,
Keywords: biomechanics, gait analysis, loads
Introduction
It is usual to see in school very fragile children carrying voluminous and very weighted backpacks with consequent overloads in their locomotor structures. Studies in the literature
showed that for children in school age, the limits of load carried should not be superior than 10 to 15% of body weight
(Voll and Klimt, 1977, Pascoe et al., 1997, Hong et al., 2000).
Thus, backpacks extremely weighted could affect the balance
and gait, inducing pain and harmful alterations in their muscle
skeletal system. The aims of this study were to analyse: (i) the
loads that children from 5th and 6th grade school usually carry
in their backpacks, (ii) the association of these loads with
back-pain symptoms, and (iii) the biomechanical repercussions
in gait and balance of children transporting these loads.
Methods
An epidemiological study was performed to understand the
fluctuation of the backpack’s weight during a school week and
the usual way how children transport their bags, as well as the
incidence of back-pain. The experimental study included: (i) a
3D kinematical analysis (ARIEL APAS system), (ii) a dynamometric analysis (Bertec Force plate), (iii) a podobarometric
analysis (PEDAR plantar pressure system). These approaches
were used for gait analysis of children with three different
loads situations (0%, 15% and 30% of the body weight).
Results
The results showed that most of the children carry overloaded
backpacks. 89% of the inquired children carried a backpack
that weighted 15% of their own body weight and 83% of these
children had already reported back-pain, probably related with
their overloaded backpacks. These backpacks are responsible
for an increase of the trunk angle that may lead eventually to
muscle skeletal injuries. The results also showed that there are
acute biomechanics repercussions in gait and balance with the
increasing load, specially when the load is above 30% of the
individuals body weight. These situations, repeated in a daily
Studies to assess total body fat from surface anthropometric
techniques in children have generally used upper limb or trunk
skinfolds as prediction variables. However, skinfolds from the
lower limb, especially the anterior thigh region, are better predictors of body fat in adults. The purpose of this study was to
assess whether the addition of a skinfold from the lower body
would improve the prediction of percent body fat when this
was predicted from the sum of the triceps and subscapular
skinfold, as this combination of skinfolds is commonly used to
predict body fat in children (Slaughter et al., 1988; Human
Biology, 60: 709-723).
Twenty eight children, 17 girls (age 9.3 ± 0.5 y; ht 134.0 ± 6.0
cm; mass 33.5 ± 8.7 kg) and 11 boys (age 9.8 ± 0.5 y; ht
136.3 ± 9.2 cm; mass 33.2 ± 6.5 kg) volunteered to participate. Percent body fat (%fatUW) was estimated by hydrodensitometry, using equations for prepubertal children. Skinfold
measurements were taken at the triceps, subscapular, anterior
thigh and medial calf. All skinfolds were made available in a
stepwise multiple regression analysis. This also included the
sum of the triceps and subscapular skinfolds (triceps+subscap)
and the sum of the calf and thigh skinfolds. Further analyses
involved hierarchical multiple regression analyses to account
for the unique variance in %fatUW from the thigh and calf
skinfolds, when these were added to the sum of triceps and
subscapular skinfolds.
Stepwise regression analysis with all variables made available
for inclusion in the analysis produced the following equations:
%fatUW in girls = 8.8 + 0.65 (thigh skinfold), R2 = 0.41);
%fatUW in boys = 3.5 + 0.9 (triceps+subscap) , R2 = 0.47).
For girls, the addition of the triceps+subscap to the thigh
accounted for less than 0.5% variance in %fatUW. For boys, the
addition of the thigh to the triceps+subscap accounted for no
further variance in %fatUW. When the thigh skinfold was
forced into the analysis at the first step (R2 = 0.45), the additional variance accounted for by inclusion of the triceps+subscap (2.0%) was non-significant (P=0.57).
In conclusion, this study provides evidence for the potential
usefulness of the thigh skinfold for predicting percent body fat
in children, especially girls.
65
revista
19.9.03
0:50
Página 66
PORTUGUESE OBESITY IN MALE AND FEMALE SCHOOL AGE
CHILDREN: EPIDEMIOLOGICAL STUDY AND OBESITY CUT OFF
POINTS VALIDATION
Silva António, Mourão-Carvalhal Maria I, Garrido Nuno,
Leitão Carlos
University of Trás-os-Montes and Alto Douro, Portugal
Keywords: body mass index, obesity, overweight
Nowadays the incidence of obesity in childhood is considered a
public health problem in developed countries. The main related
factors are sedentary lifestyles, physical activity and diet.
Therefore, one of the main concerns of public health politics
must be related to the estimation of the incidence of overweight and obesity, mainly in children in order to prevent the
associated risks in adults (active population). Therefore, the
main purpose of the present study is, on one hand, estimate
the incidence rate of obesity in school age Portuguese children
and, on the other hand, validate the proposed cut off points
from Cole et al. (2000) for the Portuguese Population. The
sample was constituted by 2651 children (1330 females and
1321 males) ranged between 6 and 10 years old, which attending primary school. For obesity and overweight criterion we
used the Body Mass Index distribution (above 25 Kg/m2 and
above 30 Kg /m2) according to the cut off points defined and
used by Cole at al. (2000). To compare the BMI index between
genders we used the analysis of variance. To adjust the BMI
index to the distraction caused by the age we use the analysis
of covariance. The results confirm that girls have grater relative
fatness percent than boys from 5/6 years through adolescence
(Malina, 2000). The results can be explained either by growing
and maturation factors but also by socio cultural factors. Girls
are brought up and educated to stay at home to play in small
spaces; boys on the contrary are encouraged to go out to have
more dynamic games. The differences between genders in what
concerns the way in which they are brought influence the way
as girls and boys dispend the energy in the spar time.
According to the obtained results, we can conclude that the
incidence rate of overweight and obesity is higher for girls than
for boys throughout the age (from 6 to 10,5 years old). Our
results confirm the fact that Portuguese children have percentual obesity and overweight index superior to the other
European Countries.
References
Cole T, Bellizzi M, Flegal K, Dietz W (2000). BMJ 320: 1-6
Malina R (2000). Growth, maturation and performance.
SEX- AND TRIBAL STATUS-ASSOCIATED DIFFERENCES
IN PREVALENCE OF CHILDHOOD OBESITY
Geithner Christina A1, Siegel Shannon R2, Weixel Cheryl A3
1
2
3
Gonzaga University, Spokane, Washington, USA
University of Wales Institute-Cardiff, Wales, Great Britain
Coeur d’Alene Tribal Wellness Center, Plummer, Idaho, USA
Keywords: obesity, prevalence, childhood
66
Introduction
Obesity has reached epidemic levels in children, adolescents,
and adults (Crespo and Smit, 2003). Obesity prevalence in
American Indians (AI) has escalated in the past 30-35 years
(Heyward and Stolarczyk, 1996; Sugarman et al., 1990) and is
widespread (Broussard, 1991; Jackson, 1993; Lohman et al.,
1999; Story et al., 1999). Direct measures of obesity in AI children are limited. Thus, the purpose of this study was to assess
obesity prevalence in children, ages 5-10, identified as tribal
(T) and non-tribal (NT) members.
Methods
Anthropometric data were collected on 219 children (121 boys,
98 girls). Obesity and super-obesity were operationally defined
as the 85th and 95th percentiles for body mass index (BMI) and
triceps skinfold thickness (TRI), respectively (NHANES I,
Must et al., 1991). Percent body fat (%Fat) was estimated
using age, BMI, and sex-specific intercepts (Lohman et al.,
1999): % Body fat =0.39age + 1.46BMI + intercept, where
intercept= +1.71 for girls and -2.23 forboys, SEE=4.3%.
ANCOVAs were run to compare BMI and TRI by sex and tribal
status while controlling for age.
Results
More than 21.0% of boys and girls are obese, and 32.7 % of
boys and 27.9% of girls are super-obese by BMI (Table 1).
Percentages are somewhat different by TRI. T girls have a higher BMI, on average, than NT girls (p<0.05). %Fat means also
indicate a high prevalence of obesity (boys=28.0±5.3%,
girls=31.5±5.6%), and T children are fatter than NT children
(Table 1).
Table 1. Percentages of children identified as obese and superobese
by 85th and 95th percentiles for BMI and TRI (NHANES I,
Must et al., 1991) and % Fat estimates by sex and tribal
membership status (Lohman et al., 1999).
Discussion and Conclusions
Assessments of BMI, TRI, and %Fat indicate an obesity prevalence of 21-33% in AI and non-AI children ages 5-10, and
confirm earlier findings of widespread prevalence of obesity
in AI children (Jackson, 1993; Lohman et al., 1999; Story et
al., 1999). Obesity prevalence varies with the criterion used;
however, the prevalence is higher in T than in NT children.
Trends toward greater BMI and obesity in children are important in the context of public health because: BMI tends to
track well after early childhood, obese children are at
increased risk for diabetes and other health and orthopedic
problems, and childhood obesity predicts adult obesity
(Crespo and Smit, 2003; Dwyer et al., 1998; Guo and
Chumlea, 1999; Serdula et al., 1993). Funding and implementation of community-based physical activity and nutrition
education programs are needed to prevent and reduce obesity
and its sequelae (Story et al., 1999).
revista
19.9.03
0:50
Página 67
References
Broussard BA et al (1991). Am J Clin Nutr 54 (Suppl.): 1535S1542S.
Burton BT et al (1985). Int J Obesity Relat Metab Disord 9: 155-169.
Crespo CJ, Smit, E (2003). In Andersen(Ed): Obesity: 3-15.
Dwyer JT et al (1998). Am J Clin Nutr 67: 602-610.
Guo SS, Chumlea WC (1999). Am J Clin Nutr 70 (Suppl): 145S148S.
Heyward VH, Stolarczyk L.M. (1996). Applied body composition
assessment.
Jackson MY (1993). J Am Diet Assoc 93: 1136-1140.
Lohman TG et al. (1999). Am J Clin Nutr 69 (Suppl.): 764S-766S.
Must A et al (1991). Am J Clin Nutr 53: 839-846.
Serdula MK. et al (1993). Prev Med 22: 167-177.
Story M et al (1999). Am J Clin Nutr 69 (Suppl): 747S-754S.
Sugarman JR et al (1990). Am J Clin Nutr 52: 960-966.
ASSESSMENT OF CARDIORESPIRATORY EXERCISE FUNCTION
IN OBESE CHILDREN AND ADOLESCENTS BY BODY MASS
INDEPENDENT PARAMETERS
Reybrouck Tony, Vinckx Jos, Gewillig Marc
Dept. Cardiac Rehabilitation, Dept. Rehabilitation Sciences University
of Leuven, Dept. Pediatric Cardiology and Pediatrics, University
Hospital Gasthuisberg, Leuven, Belgium
Keywords: obesity, exercise testing , pulmonary gas exchange
Introduction
In obese patients submaximal brisk walking exercise may be
very difficult to sustain, because of the extra metabolic burden
imposed by the excess body mass. Parameters of maximal aerobic exercise performance may be strikingly reduced when
expressed per kg body mass. The aim of the present study was
to analyse whether cardiorespiratory exercise function is trully
impaired in obese children and adolescents, when parameters
of aerobic exercise function are used which are independent of
body mass. Therefore the kinetics of oxygen uptake (VO2) at
the onset of exercise were studied by analysis of the normalised oxygen deficit.
Methods
The patients underwent square wave exercise testing on a
treadmill. The speed was set at 5 km/h and the inclination at
4 %. The oxygen deficit was calculated by subtracting the
VO2 measured at the onset of exercise from the steady-state
VO2 obtained at the end of the exercise. These differences
were cumulated and expressed as a percentage of the cumulated oxygen cost for the 6 min exercise test. All data are
expressed as mean and standard deviation of the mean.
Differences between groups were calculated by Student’s T
test. The local medical ethical committee approved the study.
The subjects were 17 obese patients (mean age: 11.2 ± 2.6
years), body mass was 70.7 ± 21.4 kg, body mass index averaged 28.9 ± 2.8 and percent overweight was 53.9 ± 16.5 %.
The patients were compared to a group of 18 normal controls of comparable age: 11.6 ± 2.2 years (P >0.25 patients
vs controls), body mass was 40.4 ± 10.6 kg (P <0.001,
patients vs. normal controls).
Results
In the obese patients, the oxygen deficit amounted to 7.2 ± 1.9
% and was not significantly (P >0.25) different from the value
obtained in normal controls: 6.9 ± 1.0 %. However obese
patients exercised at a higher percent of the maximal heart rate
(79 % in the obese subjects vs 70 % for normal controls). Due
to a less efficient walking economy during treadmill exercise,
VO2 (expressed per kg body mass) during submaximal exercise
was slightly higher in the obese (22.3 ± 2.7 ml O2/min/kg)
compared to the normal controls (20.2 ± 2.4 ml O2/min/kg)
(P < 0.05).
Conclusion
The similar values for O2 deficit at the onset of exercise in
obese patients compared to normal controls shows that there
is no evidence of a cardiovascular limitation of exercise capacity
in obese patients. Due to a less efficient walking pattern, VO2
during submaximal exercise was higher in the obese patients.
Therefore a same absolute work intensity is perceived as more
strenuous in obese subjects compared to normal controls.
LONG TERM FOLLOW UP OF ATHLETIC CHILDREN AND YOUNG
ADULTS WITH CONGENITAL VALVAR AORTIC STENOSIS
Wolfe Robert R, Schaffer Michael S, Yetman Anji T,
Taylor Amy L, Wiggins James W
University of Colorado Health Sciences Center
and Denver Children’s Hospital, Denver, USA
Keywords: congenital valvar aortic stenosis, exercise restriction,
sudden death
Introduction
Congenital valvar aortic stenosis (CVAS) is predominantly found
in males often with a keen interest in sport. They have normal or
increased work capacity and cardiopulmonary function (10).
Historically, because of the fear of sudden death, rather severe
exercise restrictions for both dynamic and static activities have
been imposed. Unfortunately, these restrictions have come during an era when high levels of physical activity were encouraged
by pediatric caregivers and participation in sport was encouraged
by parents and peers. Consequently, in 1978, our institution
devised guidelines for activity and sport for CVAS, and patients
have been followed closely since that time.
Methods
Starting in 1978, patients with mild to moderate CVAS were
allowed to participate in mild to moderate static sport activity as
defined by the Bethesda Task Force (8). Guidelines for activity in
the same publication would have eliminated virtually all sports
and most activity in an extremely active patient population (5).
Consequently, four more realistic criteria were established for
our study population of patients with CVAS. These criteria are as
follows: 1) cardiac catheterization peak aortic valvular gradient
or mean Doppler gradient of less than 50 mm, 2) no greater
than mild aortic insufficiency, 3) absence of significant left ventricular hypertrophy, dilation or dysfunction and 4) no evidence
of ischemia or sustained ventricular ectopy at rest or with exercise. All patients were followed closely (1-2 visits/year) with his-
67
revista
19.9.03
0:50
Página 68
tory, physical examination, electrocardiogram (ECG), echocardiography with Doppler evaluation including the peak and mean
aortic valve gradients, left ventricular (LV) wall thickness and
cavity dimensions, and LV systolic function. Each patient also
performed maximal cycle ergometry testing using the James protocol to examine work parameters, oxygen consumption (VO2),
ECG, and hemodynamic responses to exercise. Cardiac catheterization was performed when indicated. Those patients who
underwent successful surgical or interventional cardiac catheterization procedures to relieve aortic valvar obstruction were
allowed to return to pre-procedural activity levels within 3-6
months if criteria 1-4 were again fulfilled.
Results
The study group consisted of 144 closely followed patients. The
typical male/female ratio for CVAS was noted (101M/43F). All
of these patients were quite active during this time and were
restricted only from high static activities and sports as defined
by the Bethesda Guidelines (5). Eighty six patients underwent
127 CVAS gradient reducing procedures and 74 were returned
to pre-procedure activity levels after having met criteria 1-4.
During 2716 patient years, no episodes of non-orthostatic vasovagal syncope or sudden unexpected death occurred.
Discussion
The natural and unnatural history of CVAS as reported in the
1950’s-1970’s was discouraging and prompted an attitude of
pessimism about long term outlook (1-4, 7). In these series,
the incidence of sudden death was in excess of 1% per year.
Reports of syncope and sudden death, often associated with
exercise, and sometimes with a normal ECG, understandably
created an extremely conservative and restrictive attitude about
activity and CVAS (9). The second natural history of congenital
heart disease, the first prospective study of CVAS, reported a
mortality of 0.27% per year but had no official uniform policy
among the six participating institutions (6). This historical
background culminated in the Bethesda conference guidelines
for activity and sport participation (5, 8). However, these
guidelines were not based on published prospective data.
Unfortunately, the Bethesda guidelines were published in an
era of increasing emphasis on the importance of an active,
“heart healthy” lifestyle in the young plus virtual deification of
athletes and athletics in the media. Since CVAS is predominantly a disease of males who feel well and typically have normal or supranormal cardiopulmonary capacity, the stage is set
for extreme frustration, anger, and diminished self esteem.
This was magnified even more for our patients who reside in
the intermountain western United States. Individuals who live
in our referred area tend to be among the leanest, fittest and
most active in the country. Denver, Colorado, in particular is a
hotbed of sports fanaticism with four professional major league
teams, two minor league teams and the United States Olympic
Training Center close by. CVAS patients refused permission to
participate in sports or intense recreational activity would often
either ignore the advice and participate without proper follow
up or shop around until an unqualified or uninformed health
care provider would grant permission for high level sports or
recreation participation. Consequently, we felt that a reasonable compromise would be to allow more liberal guidelines for
sports activity with extremely close follow up thus creating a
more normal lifestyle with enhanced self esteem. The 25 year
results from our institution with no fatalities would appear to
68
support the prudence of this approach. Realistically, in the
United States, few individuals participate in competitive sports
after the age of 18 years and very few after 23 years of age.
Hopefully, the physical and psychological benefits of an active
lifestyle in the first 2 decades of life in patients with CVAS,
with what appears to be a very low risk, will continue through
the lifespan.
References
1) Braverman IB & Gibson S. (1957). Am Heart J. 53:487-494.
2) Campbell M. (1968). B Heart J 30:514-526.
3) Doyle EF et al. (1974). Pediatrics 53:481-490.
4) Glew RH et al. (1969). Am Heart J 78:615-625.
5) Graham TP et al. (1994). J Am Coll Cardiol 24:867-873.
6) Keane JF et al. (1993). Circulation 87:116-127.
7) Lambert EC et al. (1974). Am J Cardiol 34:89-98.
8) Mitchell J et al. (1994). J Am Coll Cardiol 24:845-866.
9) Reynolds JL et al. (1960). N Engl J Med 262:276-283.
10) Wolfe RR et al. (1994). Ped Exer Science 7:211.
RELATIONSHIP BETWEEN ULNAR VARIANCE AND
MORPHOLOGICAL CHARACTERISTICS IN FEMALE GYMNASTS.
A LONGITUDINAL STUDY
Claessens Albrecht L1, Van Langendonck Leen1, Boogaerts Inge1,
Lefevre Johan1, Philippaerts Renaat2, Thomis Martine1
1 Faculty of Physical Education and Physiotherapy, K.U.Leuven,
Leuven, Belgium
2 Faculty of Medicine and Health Sciences, Ghent University, Ghent,
Belgium
Keywords: ulnar variance, gymnastics, longitudinal study
Introduction
The popularity of gymnastics has grown tremendously since
the mid 1970s. In gymnastics, the upper extremities are often
used as weight-bearing limbs. The wrist is particularly vulnerable to injury since it is excessively and repetitively loaded.
Some authors reporting cases of stress injury of the distal radial growth plate occurring in young gymnasts suggested that
gymnastic training may lead to the development of positive
ulnar variance1,2. However, ‘cases’ are usually not representative of the morbidity in the general population at risk, and
hence, it is difficult to generalise from case reports. Well-controlled longitudinal studies on elite gymnasts are needed. The
aims of this study were: (1) to investigate the variability and
evolution of ulnar variance in young female gymnasts followed
over a 8-year–period; (2) to evaluate the relationship between
ulnar variance, and physical characteristics and maturity status.
Methods
The sample consisted of 16 skeletally immature female gymnasts tested annually between 1990 and 1997 for 7 or 8 test
sessions. Over the years the girls evolved from recreational to
subtop level gymnasts (15 hours training a week and competing at national competitions). At the start of the study the
chronological ages varied between 6 and 13 years.
Stature (cm) and Body mass (kg) were measured.
Skeletal maturity was estimated based on the Tanner-
revista
19.9.03
0:50
Página 69
Whitehouse II method. RUS-age was determined using the
radius, ulna and short bones estimation.
Ulnar variance (DIDI) was measured according to the method
of Hafner et al.3
DIDI is the distance from the most distal point of the ulnar
metaphysis to the most distal point of the radial metaphysis
measured on a hand-wrist X-ray (Fig 1).
In figure 2 the evolution of mean ulnar variance (DIDI) of 16
female gymnasts over a 8-year-period in comparison with reference data of Hafner et al.3 is shown. It is clear that the ulnar
variance of the gymnasts can be considered as normal.
Fig 1: measurement of ulnar variance
Descriptive statistics were calculated for all variables at all test
sessions.
The evolution and stability of ulnar variance was analysed by
means of inter-age correlations and analysis of variance.
Correlation analyses between ulnar variance and the anthropometric and maturational characteristics were executed.
Results
The descriptive statistics for all variables are presented in table
1. The gymnasts show a mean ulnar variance ranging from -3.4
mm at test session 1 to -6.0 mm at test session 8.
Table 1: Descriptive statistics for ulnar variance, somatic
and maturational characteristics of female gymnasts (n = 16)
F1 → F8 : test session 1 → test session 8
The inter-age correlations range between 0.59 and 0.92
(p<0.01 at r>0.60).
The correlations between the somatic characteristics and DIDI
were low to moderate and reached only significance at test session 7. No significant correlations were observed between maturation and DIDI (table 2).
Figure 2: Evolution of mean ulnar variance (DIDI) of 16 female gymnasts
over a 8-year-period in comparison with reference data of Hafner et al.
*/** respective DIDI value differs from DIDI value of the previous
test session (* p ≤ 0.05 / ** p ≤ 0.01).
Conclusion
It can be concluded that female gymnasts competing at a
subtop level show a negative ulnar variance, which becomes
more pronounced over the years when training level increases.
Compared to reference data the ulnar variance of the gymnasts
can be considered as normal. No significant relationships
between ulnar variance and somatic and maturational features
can be found for most test occasions, only a significant correlation between ulnar variance and height and weight can be
observed.
References
1. Claessens AL et al. (1996). Med Sci Sports Exerc 28:560-69.
2. Claessens AL (2001). in Lenoir M, Philippaerts R (eds), Science in
Artistic Gymnastics.
3. Hafner R et al (1989). Skeletal Radiol 18:513-16.
Table 2: Correlations between DIDI and somatic and maturational
characteristics in female gymnasts at each test session (n = 16)
F1 → F8 : test session 1 → test session 8; *p ≤ 0.05; ** p ≤ 0.01
69
revista
19.9.03
0:50
Página 70
revista
19.9.03
0:50
Página 71
PHYSIOLOGICAL AND ENDOCRINOLOGICAL
ASPECTS IN PEDIATRIC EXERCISE SCIENCE
revista
19.9.03
0:50
Página 72
revista
19.9.03
0:50
Página 73
HERITABILITIES OF PEAK VO2 IN ADOLESCENCE
Thomis Martine AI1, Vanden Eynde Bart2, Maes Hermine H3,
Loos Ruth1, Claessens Albrecht L1, Vlietinck Robert4,
Beunen Gaston1
formances level off from 14 years onward (1.39±0.28 to
2.30±0.57 l/min). Standard deviations increase with age in
both males and females, indicating increased variability in peak
oxygen uptake with age.
1 Department Sports and Movement Sciences, Faculty of Physical
Education and Physiotherapy, Katholieke Universiteit Leuven, Belgium
2 Department Kinesiology, Faculty of Physical Education and
Physiotherapy, Katholieke Universiteit Leuven, Belgium
3 Virginia Institute for Psychiatric and Behavioral Genetics, Virginia
Commonwealth University, Richmond, VA, USA.
4 Genetic Epidemiology, Centre for Human Genetics, Katholieke
Universiteit Leuven, Belgium and Population Genetics and Genomics,
University Maastricht, Netherlands
Keywords: interindividual variability, genetics, sex-specific modeling
Introduction
Studies on the importance of genetic and environmental factors
explaining variability in peak or maximal oxygen uptake lack data
on females and the period of rapid growth in adolescence. More
extensive heritability estimations are available for males and
young adults. Heritability estimates vary from about 40 to 90%,
with estimates from family studies showing consistently lower
estimates except when the age range of the children is rather
small (Maes et al; 1996). The present study offers the possibility
to quantify the contributions of genetic and environmental factors in VO2 peak values, from 10 to 18 years of age in both male
and female twins of the Leuven Longitudinal Twin Study.
Methods
VO2 peak value was measured in 91 twins at the last stage of
the Bruce treadmill protocol (RQ > 1.00, HF > 180
beats/min). Longitudinal evaluations were taken at yearly
intervals, however, sample sizes dropped from 91 to 73 at 15
years of age and to 60 and 42 at 16 and 18 years respectively.
VO2 peak values were analyzed as raw data (l/min), relative to
body weight (l/min/kg) and as residual scores (l/min) after age
and sex-specific regression of weight on VO2 peak. Several sexspecific genetic and environmental path-analytic models were
fitted to the data at each time point separately to select the
most parsimonious model by Akaike’s Information Criterion.
Different sources of variation were tested: A= additive genetic
factors, D= dominance genetic factors, C= common environmental factors – shared by members within a family, and E=
unique environmental factors. Alternative models tested for
evidence of different sets of genes acting in males and females,
overall differences in total variation, or different contributions
of each source to the total variation (specific scalars, SS).
Alternative models were compared based on their Akaike’s
Information Criterion. For the best-fitting model, contributions
of each source of variations in males and females were
expressed compared to the total variation, giving variance components estimates. For the a2 (narrow heritability), 95% confidence limits are presented.
Results
Cross-sectional analysis of peak VO2 data indicate a clear
increase in peak oxygen uptake in males (1.63±0.38 to
3.75±0.80 l/min) with a non-linear increase, indicative for a
growth spurt (figure 1). For girls increases are smaller and per-
Figure 1. Evolution of peak VO2 (l/min) in males and females
from 10-18 years of age (cross-sectional analysis).
Figure and table 2 present the results of model-fitting of variation in peak (l/min) at each age. Goodness-of-fit indices show
no significant Chi2 values, indicating that the most parsimonious model represents the data sufficiently well. No evidence
was found for differences in sets of genes that contribute to the
observed sex-differences in VO2 peak during growth (table 2).
Most models indicated a sex-specific contribution of one source
of variation (e.g. SS VO2E AE at 11 years) meaning that e.g.
unique environmental factors had a different contribution to
the variation in peak VO2 at 11-years of age in males and
females, but genetic factors had equal non-standardized path
estimates. When expressed to the total variation, sex-specific
h2 and e2 are given. Large differences were observed in the
heritability estimates. For the raw VO2 peak values, h2 varies
from 28-94% in females, with larger contributions of the specific environment from 16 years onwards. In males, very high
dizygotic intra-pair correlations induced high contributions of
common environmental factors (45-83 %) at 10 years and from
14 years onward.
In general, heritability estimates increased from 10 to 13 years
of age in both males (32%-83%) and females (58-64%).
Contributions of individual environmental factors as well as
shared environmental factors (in males) increased in importance from 14 to 18 years of age (h2 about 0% in males, drops
from 84% to 28% in females).
When peak VO2 is expressed relative to body weight
(l/min/kg) (figure and table 3), a slightly different result was
found. Common environmental factors seem to become more
important at 10 and 12 years of age in both males and
females, but disappeared as significant contributing factors
from 14 years onward. Heritability estimates for peak VO2 per
kg body weight are therefore small at age 10 and 12 especially
in males, but vary between 69% and 79% in males and
between 69% and 92% in females from 13 to 18 years of ages,
without a clear age trend.
73
revista
19.9.03
0:50
Página 74
females at most ages. In general, heritability estimates are
lower when body weight is not taken into account. For males
environmental factors shared within the family seem to contribute to variability in peak VO2 (l/min) at 10 and from 14
years onward, however this factor is not significant when peak
VO2 is expressed relative to body weight (l/min/kg) and therefore heritability estimates are higher for peak VO2 (l/min/kg)
compared to peak VO2 (l/min) in males.
In females only additive genes and unique environmental factors contribute to the observed variability in uncorrected peak
VO2 values with increasing heritabilities from 10 to 14 years of
age, followed by a decreasing trend. A similar result was
observed for relative peak VO2 measures, except at 10 and 12
years of age where shared environmental factors also contributed to the total variation.
Further multivariate longitudinal model-fitting is needed to
answers questions about time-specific contributions of new
genetic and environmental factors in VO2 peak determination
during growth. Furthermore, allometric correction of VO2
measures for weight, height or lean mass might more correctly
represent changes in oxygen uptake during the period of rapid
growth in adolescence.
Figure & table 2. Variance components (% explained variance)
and 95% confidence intervals (a2) for peak VO2 values (l/min) in 10
to 18-year-old girls (F) and boys (M). Goodness-of-fit indices are
presented for the most parsimonious model at each age.
References
Maes HHM, Beunen GP, Vlietinck RF, Neale MC, Thomis M, Vanden
Eynde B, Lysens R, Simons J, Derom C, Derom R,
(1996). Med Sci Sports Exerc 28: 1479-1491.
GENDER DIFFERENCES IN PEAK MUSCLE PERFORMANCE
DURING GROWTH
Doré Eric, Martin Ronan, Bedu Mario, Duché Pascale,
Van Praagh Emmanuel
Laboratoire Inter-Universitaire de Biologie des Activités Physiques
et Sportives, France
Keywords: peak muscle power, gender, growth
Figure & table 3. Variance components (% explained variance) and
95% confidence intervals (a2) for relative peak VO2 values (l/min/kg)
in 10 to 18-year-old girls (F) and boys (M). Goodness-of-fit indices
are presented for the most parsimonious model at each age.
The present study investigated the importance of genetic and
environmental factors as contributing factors to variability in
peak oxygen consumption in longitudinally evaluated male and
female adolescents. Heritability estimates differ for males and
74
Most research in the area of pediatric exercise science has traditionally been limited to male individuals. Because short-term
muscle power (STMP) has been little investigated compared to
prolonged maximal power, gender differences in STMP during
growth has still to be clarified. The present study was undertaken to determine gender differences in changes in maximal
leg power during growth. A non-selected population of 583
females and 530 males aged 8 to 20 years volunteered for the
study. The population was divided in six age-groups (8-10, 1012, 18-20 years of age). Anthropometric characteristics included height, body mass, leg length (LL) and lean leg volume
(LLV). All subjects performed three all-out sprints on a cycle
ergometer against three different braking forces (1.5, 2.5 and
5% of body weight for children up to 12 years and 2.5 and 5
and 7.5% of body weight for the other individuals) to determined cycling peak power (CPP, including the force required to
accelerate the flywheel of the cycle ergometer) and optimal
velocity (Vopt, cycling velocity at CPP). No significant genderdifferences were observed up to 14 years old in anthropometric
characteristics and CPP. From 14 years old however, males
showed a higher CPP than females (p<0.001), but also a high-
revista
19.9.03
0:50
Página 75
er lean leg volume (p<0.001). Comparison of allometric relationship between CPP and LLV [ln CPP = ln(a) + b ln(LLV)]
using ANCOVA showed a clear gender-differentiation
(p<0.001) in adjusted CPP changes between 14 and 16 years
(b = 0.71 in females vs. b = 1.02 in males). As a consequence,
from 16 years of age, for similar body dimensions, males have a
greater CPP than females. This gender-difference was also
observed for optimal velocity adjusted for leg length.
Therefore, from onwards age 14, for similar leg length, males
have a higher optimal velocity (velocity at CPP) but also a
higher maximal velocity than females. Qualitative muscle factors such as fiber type, neuromuscular activation or muscle
enzyme activities might be responsible for this difference.
A LONGITUDINAL STUDY OF TETHERED SWIMMING FORCE
IN COMPETITIVE AGE GROUP SWIMMERS
Taylor Suzan R1,2, Stratton Gareth1, MacLaren Don PM2,
Lees Adrian2
1 REACH (Research into Exercise Activity and Children’s Health)
Group, Faculty of Education, Community and Leisure, Liverpool John
Moores University, Liverpool, UK
2 Research Institute for Sport and Exercise Sciences, School of Sport
and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
Methods
Subjects
A total of forty seven girls initially volunteered to take part in
the study. The subjects were highly trained individuals who,
for the 12 months prior to testing had completed at least 4
training sessions per week of 1.5-2 hours duration. Prior to
the start of the study, parents and children were informed verbally and in writing of the experimental procedures. Parents
and children also provided written consent in accordance with
the University Ethics Committee. The study used a mixed longitudinal design with measurements taken at approximately 6
month intervals.
Tethered Swimming System Design
The fully-tethered swimming system consisted of a PC laptop
computer (Toshiba Satellite 230CX, Tokyo, Japan) and software
(PowerLab™ System, Chart for Windows®, ADI Instruments,
Castle Hill, Australia), a starting block (used to anchor the
force transducer), an amplifier (FE 359 TA 12v conversion,
Fylde Electronic Labs, Preston, UK), a PowerLab™/400 system
(ADI Instruments, Castle Hill, Australia), a 100 kgf force transducer (V4000, Maywood Instruments, Hampshire, UK), 3 karabiners (1000kN, EB Viper, Bangor), 6 m of pre-stretched rope
(diameter 0.5 cm), and a climbing belt (Trat, Arizona, USA). A
diagrammatic representation of the tethered swimming system
is given in Fig 1.
Keywords: longitudinal study, multilevel modelling, age group swimmers
Introduction
While much work has been carried out on the development of
aerobic fitness in children considerably less attention has been
applied to the development of anaerobic performance. The
majority of the data in the literature are confined to untrained
populations using young boys and fail to quantify level of maturation, preferring to use chronological age which has been
shown to be a poor indicator of maturity (Matsudo and
Matsudo, 1993). Studies involving girls are limited, with a
particular lack of information available for the 13-16 year old
age range. In addition the assessment of anaerobic performance in young athletes is an issue which has been addressed by
few researchers, with the main basis of our current knowledge
of the development of anaerobic performance based on nonathletic children. It is however, inappropriate to assume that
trained children will perform in the same way as non-athletic
children. Swimming offers an ideal opportunity to study the
influence of these factors, as swimmers participate in regular
training from a young age and training is generally prescribed
in terms of chronological age.
The assessment of power output in swimming is complex due
to the differences in body position, motor recruitment patterns
and the fact that swimming takes place in the medium of
water. At the present time tethered swimming is the most
appropriate method to use with swimmers (Rohrs et al., 1990).
However ‘power output’ cannot be determined as there is no
forward velocity, as a result mean tethered force (MTF) is used
as an indictor of anaerobic performance. Therefore the aim of
this study was to assess the changes in anaerobic performance
in circumpubertal competitive swimmers.
Fig. 1: A schematic diagram of the fully tethered swimming system.
The force transducer was attached to the starting block via a 15
cm length of pre-stretched rope that was looped around the
backstroke bar and had a karabiner to attach the force transducer, via the eyebolts. The signal from the force transducer
was amplified by a transducer amplifier which was linked to a
data acquisition module that consisted of an analogue-to-digital (A/D) converter and software. A sample rate of 100 Hz
was used for all data collection.
The force transducer was calibrated prior to testing by hanging
a series of known masses (0,10, 20, 30, 40, and 50 kg) from
the force transducer. As the force vector in the tether was at a
small angle to the horizontal (Fig. 1), the data were corrected
by computing the horizontal component of force. The raw data
were averaged every second over the 30 s period; from this
mean force was calculated.
Experimental methods
Decimal age was computed from the date of birth and date of
testing. The maturity status of the subjects was assessed
using a self-assessment questionnaire devised by Morris and
Udry (1980). Fourteen anthropometric measures were also
75
revista
19.9.03
0:50
Página 76
taken, these included stature, body mass, circumferences
(bicep (relaxed), calf, and chest), breadths (biacromial and
biiliac), lengths (acromiale-radiale, radiale-stylion, hand, foot,
arm span), and body composition (subscapular and triceps
skinfolds) using the standardised procedures outlined by
Lohman et al. (1991).
In order to standardise the testing procedure subjects were
tested at the same time of day across the 18 month period, as
diurnal variation is known to affect swimming performance
(Martin and Thompson, 2000). In addition subjects were
asked to refrain from training on the day of testing and to standardise their nutritional intake.
Prior to testing the subjects completed a standardized warm-up
(700 m). The subjects then completed a tethered familiarisation which included a 30s practice test, this was followed by a
30min low intensity (heart rate 120-140 beats • min-1) standardized training session which preceded the actual 30s tethered swimming test. The reliability of tethered swimming force
in age group swimmers has been reported elsewhere (Taylor et
al., 2001). In the tethered swim test, the swimmers commenced from a rolling start, which involved taking up the slack
in the rope and swimming sub-maximally until a whistle was
blown. The subjects were verbally encouraged throughout the
test, instructed to avoid pacing and to maintain maximal effort
for the duration of the test. The raw data were averaged every
second of the 30s period and from this MTF was calculated.
Immediately after the test the subjects completed a standardised swim down (400 m).
Data Analysis
Descriptive statistics for the anthropometric variables were calculated for each phase of the testing using SPSS (ver 11.0.1,
SPSS Inc, 2001).
Factors associated with the longitudinal development of anaerobic performance, such as age, maturity status and anthropometric measures were investigated using the multi-level modelling program MLwiN (version 1.12, Rasbash et al., 2001).
Multilevel modelling is fundamentally an extension of multiple
regression and allows the assessment of nested or hierarchical
data. In longitudinal data sets, the hierarchy can be described
as the repeated measurement occasions (level 1 units) and
individual subjects (level 2 units).
In the present study a multiplicative allometric model was used
in which all parameters were fixed with the exception of the constant (intercept term) and age parameters which were allowed to
vary randomly at level 2 (between individuals) and the multiplicative error ratio ε, which described the variance at level 1
(between occasions). The subscripts i and j denote random variation at levels 1 and 2 respectively. ‘Age’ was centred (subtracting
the mean age from each subjects decimal age) on the group mean
of 12.9 years to make the interpretation of the intercept term easier and to reduce the risk of numerical errors when using the
Iterative Generalised Least Squares (IGLS) estimation method.
The model was linearised by using log-transformation.
the model as a categorical variable.
The multiplicative allometric model has been shown to be statistically superior to the additive polynomial model which was
first proposed by Goldstein (1986), as it accommodates the
skewness and heteroscedasticity which is often present in sizerelated exercise data (Nevill et al., 1998).
Results
The swimmers physical characteristics and time trial performance are described in Table 1.
Table 1: Physical characteristics and time
trial performance of the swimmers.
* Sum of triceps and subscapular skinfolds. **50 m Freestyle Time
Trial performed from a push start. Values are means (SD).
In a multilevel model the fixed parameters describe the subject
population mean response and the random parameters reflect
the individual departures from the mean response or the variation at both level 1 (within individuals or between occasions)
and level 2 (between individuals). The intercept (constant)
and age were allowed to vary randomly at level 2, which
ensured that each child had their own growth trajectory over
the test period.
The first model is the baseline, and from this baseline model
other anthropometric measures were investigated as additional
explanatory variables. Due to multicollinearity between the
anthropometric variables, only measures that were significantly
correlated but not collinear (i.e. r < 0.8) with arm span were
included in the model. The statistical significance of a parameter is determined by dividing the value of the parameter estimate by its standard error term. If this value exceeds ± 2.0,
the estimate may be considered significantly different from
zero P<0.05 (Duncan et al., 1996). The deviance statistic (the
log likelihood value) describes the models goodness of fit. In
hierarchical data, such as the present data, the log likelihood
value is negative and therefore the smaller the number the better the fit. However, the log likelihood value must be considered in relation to the number of fitted parameters, and as a
result, a reduction in the log likelihood value does not necessarily indicate a ‘better’ fitting model.
Table 2: Multilevel regression analysis for mean tethered force (n=166)
Loge MTF = (k1 x loge arm span) + αj + (bj x age) + loge εij
Where: k1 = loge arm span, α = constant, b = centred age and
loge ε = multiplicative error. The subscripts i and j denote random variation at levels 1 and 2 respectively. From this baseline
model, additional explanatory variables were investigated.
Where maturity was found to be significant it was entered into
N.S. Non –significant P > 0.05.
76
revista
19.9.03
0:50
Página 77
Table 2 shows the results of the multilevel regression analysis
for MTF. The inclusion of arm span proved to be a significant
explanatory variable in the baseline model with an exponent of
1.657 (± 0.306), which made the age parameter non-significant. The random components of the model at level 2 showed
that age and the covariance of the slope were non-significant,
whereas the intercepts at level 1 and 2 were significant. The
baseline log likelihood value was –290.299.
The addition of the subscapular skinfold measurement
improved the fit of the model, with a significant change (P <
0.01) in the log likelihood value compared to the baseline
model for one more parameter. Furthermore calf girth also
imparted a significant (P < 0.01) effect on mean force production (model 3). The inclusion of the third anthropometric
exponent in the model decreased the arm span and the subscapular skinfold exponent increased from -0.131 to -0.173.
The log likelihood value decreased by 9.861, which signifies
that the third model accounted for more of the variance than
the preceding models and is consequently a better statistical
fit. The final significant explanatory variable added was maturity (Tanner Stage V), which was found to have a negative
effect on MTF.
Discussion
Longitudinal studies represent the most rigorous approach to
studying the interaction of growth and maturity on anaerobic
performance, however the analysis of longitudinal data sets has
until recently been challenging, especially when the data are
sampled in relation to body size and composition. With the
advent of multilevel modelling more flexible and sophisticated
analyses can now be conducted on data (Welsman and
Armstrong, 2000).
Armstrong et al. (2000) used multilevel modelling to examine
the effects of age, body size, skinfold thickness, gender and
maturation on the short-term power output. These analyses
revealed a significant sex-related difference in short-term
power output, and a significant effect of later maturity on
mean power output. In a later study using the same subjects,
Armstrong et al. (2001) examined the development of mean
and peak power output over 5 years. Despite a reduction in
the sample size mean and peak power output were shown to
increase with age but there was no effect of maturity. In addition, De Ste Croix et al. (2001) reported no effect of maturity
on mean or peak power output in children aged 10 to 12 years.
Previous studies have demonstrated the influence of stature and
body mass on mean and peak power (Armstrong et al., 2000;
Armstrong et al., 2001; De Ste Croix et al., 2001) and have subsequently included both variables in the baseline allometric
equation. However, as the mean force production measurements are performed in water, body mass cannot be used to differentiate between swimmers, as the weight of the body is
reduced to a few kilograms when submersed in water. As a
result the stature term was replaced by arm span which was
found to be a better predictor of anaerobic performance and has
been involved in the prediction of sprint ability among swimmers (Carter and Ackland, 1994). The precise meaning of the
arm span effect is thought to be related to stroke length and
stroke frequency in 50 and 100 m freestyle events (Pelayo et al.,
1996) and may consequently affect the application of force over
the 30 s maximal test. In addition, the force produced by the
arm is the product of the characteristics of the all of the muscles that span the shoulder joint and the musculoskeletal archi-
tecture, both of which are altered during puberty.
Although the arms provide most of the propulsive force in
swimming, the legs also make significant contributions to the
overall force, with the kick accounting for up to 25% of the overall propulsion in sprinters (Vorontsov and Rumyantsev, 2000).
Young swimmers are more reliant on propulsion from the legs
until sufficient strength is developed in the arms, back and
trunk. Athletes who perform on land have the daily stimulation
of walking and standing from approximately 9-16 months old,
whereas swimmers receive virtually no training of the muscles
used in swimming (arm, back and trunk) unless in the pool.
The significant negative effect of skinfold thickness on anaerobic performance has previously been reported in untrained children (Armstrong et al., 2000; Armstrong et al., 2001; De Ste
Croix et al., 2001). The results of the present study generally
show that those swimmers with lower subscapular skinfold
values have a higher anaerobic performance and therefore support the findings reported in untrained children (Armstrong et
al., 2000); Armstrong et al., 2001; De Ste Croix et al., 2001).
The final significant explanatory variable added to the model
was maturity (Tanner Stage V), which had a negative affect on
MTF. The impact of maturity on anaerobic performance is relatively unknown; the present study is the first to address the
impact of maturity on anaerobic performance in children aged
10 to 15 years. Previous studies have looked at children of the
same age who span the five maturation stages but the results
appear to be contradictory (Armstrong et al., 2000; Armstrong
et al., 2001; De Ste Croix et al., 2001). The results of this
study indicate that the mature girls generate less MTF relative
to changes in body size.
In summary all variables except age made significant contributions to the prediction of MTF. This finding indicates that
MTF increases at the same rate as increases in body size.
Although age was not a significant explanatory variable in the
model it must be retained as it is allowed to vary for each
swimmer in the random part of the model. In conclusion these
results indicate that the development of MTF is proportional to
the general increases in arm span, calf girth and subscapular
skinfold thickness up to Tanner stage V when the development
of MTF is altered.
References
Armstrong N, et al (2000). Med Sci Sports Exerc 32:1140-1145.
Armstrong N, et al (2001). Brit J of Sports Med 35:118-124.
Carter JEL and Ackland, TR (1994). Kinanthropometry in Aquatic
Sports: A study of world class athletes. Champaign, Ill: Human
Kinetics.
De Ste Croix MBA, et al (2001). J Sports Sci 19:141-148.
Duncan C et al (1996). Social Science and Medicine, 42, 817-830.
Goldstein H (1986). Ann Hum Biol 13, 129-141.
Lohman TG et al (Eds.) (1991). Anthropometric Standardization
Reference Manual. Champaign, Ill: Human Kinetics.
Martin L and Thompson K (2000). Int J Sports Med 21, 387-392.
Matsudo SM and Matsudo VR (1993). In World-Wide Variation in
Physical Fitness (AL Claessens, J Lefevre, B Vanden Eynde, Eds), pp
106-110. Leuven: Institute of Physical Education.
Morris NM and Udry R (1980) J Youth Adolescence 9: 271-280.
Nevill AM et al (1998). J Appl Physiol, 84, 963-970.
Pelayo P et al (1996). J Appl Biom 12:197-206.
Rasbash J et al (2001). A user’s guide to MLwiN version 2.1c.
London: Centre for Multilevel Modelling, Institute of Education,
University of London.
77
revista
19.9.03
0:50
Página 78
Rohrs DM, et al (1990). J Swim Res 6:15-19.
Taylor SR, et al (2001). Sports Sci 19:12-13, (Abstract).
Vorontsov A and Rumyantsev VA (2000) In Biomechanics in Sport
(VM. Zatsiorsky, Ed), pp 224. London: Blackwell Science.
Welsman JR, and Armstrong N (2000). Pediatr Exer Sci 12: 112-127.
Deighan Martine*, De Ste Croix Mark, Wood Louise,
Armstrong Neil
Children’s Health and Exercise Research Centre,
University of Exeter, UK
Keywords: concentric , eccentric, children
THE ATTAINMENT OF PEAK VO2 DURING SUPRAMAXIMAL
INTENSITY SPRINT CYCLING
Williams Craig, Ratel Sebastien
Children’s Health and Exercise Research Centre, Exeter, UK
Keywords: peak oxygen uptake, supramaximal sprinting, isokinetics
Previous evidence in adults suggests that a plateau in power
decrement occurs during all out exercise of >80 s. When such
a plateau in power is reached it has been hypothesised that the
power is maintained as the same rate as for aerobic metabolism during a peak oxygen uptake (peak VO2) test. The aim of
the study was to compare the PVO2 obtained from a conventional ramp test to exhaustion in adolescents to the PVO2
attained in a 90s supramaximal intensity cycle sprint.
Seventeen adolescents (14 boys and 3 girls, 14.6±0.3 y) volunteered to participate, which was approved by the ethics committee of the University. On day 1 participants completed a
PVO2 test on an isokinetic cycle ergometer (SRM, Julich,
Germany) to volitional exhaustion using a 25 W.min-1 ramp
protocol commencing at 50W. Peak VO2 was defined as the
highest VO2 value as determined by a stationary 10s average
and aerobic maximal power (Wmax) was calculated from the
final 30s of the test. After a 24 hr recovery period, participants
returned to the laboratory and completed two 90s supramaximal sprints (S1 & S2) at a fixed cadence of 110rev.min-1. The
sprints were separated by a 45 minute recovery period. In all
tests (ramp, S1 & S2) pulmonary gas exchange was measured
breath-by-breath using a mass spectrometer (CaSE QP9000,
Morgan Medical, Kent). Peak power (PP) was determined as
the highest power output over 1s and minimum power (MinP)
as the power attained in the last 30s of the supramaximal 90s
sprints. The oxygen uptake attained during the final 30s was
determined as the PVO2 value for S1 & S2. All oxygen uptake
data were interpolated and time aligned to 1 s intervals.
Differences between the ramp and sprint protocol for PVO2
and power were analysed using Student’s paired t-test. The PP
for S1 & S2 were 538±129 and 533±139 W respectively. Peak
was VO2 not significantly different between the ramp, S1 or S2
(2.6±0.6, 2.5±0.5 and 2.5±0.5 L.min-1 respectively, p> 0.05).
The MinP for S1 (137±53 W) and S2 (154±60 W) were significantly different to the max (211±42 W) of the ramp test (p<
0.05). The PVO2 , but not the MinP, produced in a supramaximal 90s sprint is comparable to that achieved in a conventional
aerobic ramp test. Hence for researchers solely interested in
PVO2 values, a shorter but more intensive protocol may suffice.
THE ECCENTRIC/CONCENTRIC RATIO OF THE KNEE AND ELBOW
EXTENSORS AND FLEXORS OF CHILDREN AND ADULTS
Previous literature has indicated a greater Eccentric/Concentric
ratio (Ecc/Con) of muscle groups in women than men (Griggin
et al. 1993; Seger and Thorstensson 1994) but the Ecc-Con
relationships of the knee and elbow musculature in children
has been less well studied. Therefore the aim of this study was
to determine if there are sex or age-associated differences in
the Ecc/Con of the elbow and knee extensors and flexors (EE,
EF, KE and KF). 21 boys and 24 girls with a mean age of
9.5±0.4 y and 21 males and 21 females with a mean age of
24.3±3.6 y volunteered for the study. After a separate day
familiarisation, Con and Ecc isokinetic peak torque was
assessed at 0.52 rad/s using a Biodex System 3. After a warmup of 3min cycling, 20s stretches and 3 submaximal and 1
maximal Con extension/flexion cycles on the Biodex, 3 maximal continuous extension/flexion cycles were performed with a
2min rest between the Con and Ecc test. The data were gravity
corrected, windowed and the greatest torque value was selected for analysis. The significance level for all statistical tests was
p<0.05. One sample t-tests revealed that Ecc/Con was greater
than 1.0 except for EE Ecc/Con in both female groups and the
male children. Sex by group (2 by 2) ANOVA revealed no significant effects for KE Ecc/Con which had a mean of 1.28, but
a significant group effect was found (p=0.012) for KF Ecc/Con
with the ratio of the children (1.70±0.42) being higher than
that of the adults (1.52±0.31). There was a main effect of sex
(p=0.029) for EE with the males Ecc/Con being higher than
that of the females (1.19±0.23 vs. 1.09±0.20). The analysis of
EF Ecc/Con indicated significant main effects of sex (p=0.010)
and group (p=0.010) which reflected higher ratios in the
adults (male 1.29±0.26, female 1.33±0.23) than the children
(male 1.22±0.29, female 1.29±0.25) and in females than
males. No interaction effects were found for any of the
Ecc/Con variables. In conclusion, the results of this study do
not indicate a particular trend with respect to sex or age differences in the Ecc/Con of the knee and elbow extensors and flexors and with the exception of EF Ecc/Con there was no indication that Ecc/Con is greater in females than males.
Griffin, J.W. et al. (1993). Medicine and Science in Sport and
Exercise, 25, 936-944
Seger, J.Y. and Thorstensson, A. (1994). European Journal of
Applied Physiology, 69, 81-87
*(Dr. Deighan is now with the University of Wolverhampton)
PLANTAR FLEXION TORQUE PER UNIT MUSCLE
CROSS-SECTIONAL AREA IS SIMILAR IN BOYS AND YOUNG MEN
Tolfrey Keith, Morse Chris, Thom Jeanette, Vassilopoulos Will,
Narici Marco V
Manchester Metropolitan University, England
78
revista
19.9.03
0:50
Página 79
Keywords: specific torque, ACSA, boys
The effect of biological maturation on specific torque is not
clear. To this end, the purpose of this study was to compare
maximum plantar flexion torque per triceps surae (TS)
anatomical cross-sectional area (ACSA) in boys and young
men. Twelve early pubertal boys (mean (SD) 11.3 ± 0.3 y; 1.46
± 0.03 m; 39.0 ± 8 kg; pubic hair stage 2) and ten young men
(24.3 ± 4.8 y; 1.80 ± 0.08 m; 77.3 ± 13 kg) volunteered for
the study. Torque was measured at six different ankle joint
angles, from 20 deg dorsiflexion (-20 deg) to 30 deg plantar
flexion (+30 deg), with the participants lying prone (knee at
180 deg) using a Cybex dynamometer. The TS ACSA (cm2) was
determined in vivo using magnetic resonance imaging (MRI).
Specific torque was then calculated as the ratio between maximum torque at the optimal angle of -20 deg and TS ACSA
(Nm.cm-2). Between group differences were assessed using
independent Student’s t-tests. Zero order correlations were
used to examine the relationships between TS ACSA and the
torque values at each joint angle in the separate groups.
In both boys and young adults, maximum torque was attained
at -20 deg of dorsiflexion. At this angle, maximum torque was
75 ± 23 Nm in the boys and 163 ± 43 Nm in the young men.
Similarly, TS ACSA was 29 ± 9 cm2 in the boys and 60 ± 10
cm2 in the young men. The ACSA of the gastrocnemius medialis (GM) and lateralis (GL), and the soleus as a percentage of
the TS ACSA was the same for both groups (29%, 20%, and
51% respectively, P>0.05). For the boys, the correlations
between TS ACSA and torque ranged from r = 0.81 to 0.91
across the different joint angles (P<0.001). In contrast, the
relationship was weaker in the men, r = 0.53 to 0.66. When
normalised for TS ACSA, the maximum torque of the boys
was 2.64 ± 0.4 Nm.cm-2 and 2.71 ± 0.6 Nm.cm-2 in the young
men (P>0.05).
It is concluded that, despite the significantly smaller TS crosssectional area of these early pubertal boys, their maximum
torque scaled to muscle size in the same fashion as that of the
young men. Hence, the specific torque of these 11 year old
boys was not different from the men’s.
EFFECTS OF HIGH-INTENSITY TRAINING ON EXERCISE
PERFORMANCE OF PRE-ADOLESCENT FEMALE SOCCER PLAYERS
Grossner Colleen M, Johnson Emily M, Cabrera Marco E
Pediatrics, Case Western Reserve University, Cleveland, Ohio, USA
Keywords: high-intensity, soccer, training
Introduction
Children ordinarily engage in short bursts of high-intensity
physical activity interspersed with periods of moderate or low
activity (Bailey). Consequently, exercise programs that mimic
this pattern of physical activity may foster improved adherence
to the training regime by children, therefore promoting physiological adaptation to conditioning. However, the actual metabolic responses to high-intensity exercise are unknown in a
pediatric population.
Traditionally, an improvement in maximal O2 uptake (VO2max)
has been the most common criteria used to determine the
effectiveness of training programs in adults. However, when
children have been trained, increases in VO2max are not always
evident (Williams). Therefore, changes (post- minus pre-training values) in submaximal parameters of exercise performance
(e.g., lactate threshold (LT), submaximal oxygen uptake
(VO2submax), heart rate (HR), minute ventilation (VE) may be
more appropriate indicators of the physiological adaptation to
exercise training.
Therefore, the purpose of this study was to examine the effects
of an 8-week high-intensity intermittent running program on
exercise performance and cardiorespiratory function on a group
of healthy, pre-pubertal, pre-adolescent, female soccer players.
We compared the cardiovascular, respiratory, and metabolic
responses to maximal and submaximal exercise on a treadmill
before and after training to test our hypothesis that a high-intensity conditioning program would improve peak aerobic power
and submaximal indices of performance in healthy children.
Methods
Subjects, Baseline Tests, and Experimental Design
Seven healthy, non-sedentary girls (age: 10.4 ± 0.05 yr, height:
139.4 ± 5.9 cm, weight: 32.0 ± 7.2 kg) were recruited from a
local elementary school (Shaker Heights, Ohio). All of the
subjects were pre-menarcheal and six of the seven subjects participated on a travel soccer team in addition to participation in
the program. Prior to participation, written informed consent
was obtained from a parent or guardian for all subjects. The
research protocol was approved by the Institutional Review
Board for Human Investigation of University Hospitals of
Cleveland (UHC). This study also obtained approval from the
Shaker Heights City School District.
Subjects visited the exercise lab in Rainbow Babies and
Children’s Hospital of UHC for exercise testing on 4 separate
days, for approximately 90 min/day (2 days: pre-training; 2
days: post-training). Subjects answered a modified version of
the Physical Activity Readiness Questionnaire (Canadian
Society for Exercise Physiology) to assess history of disease
and habitual physical activity. Persons with a history of chronic
disease of any organ system and persons who were not allowed
to participate in normal physical education programs at school
were excluded. Baseline testing consisted of anthropometric
measurements and two exercise tests on a treadmill (1 maximal, 1 submaximal). The training protocol included three 1hour supervised training sessions per week, on non-consecutive days for 8 consecutive weeks, after regular school hours.
During each training session, subjects ran two non-consecutive
bouts of 10 minutes each at an individually pre-determined target heart rate (85-95% HRmax) and performed soccer drills
and scrimmages for 20 minutes in between these running
bouts. The remaining portion of the exercise session was
devoted to warm-up, stretching, and cool-down exercises. In
addition to the training program, on average, girls participated
in two 1-hour soccer practice sessions and a soccer game each
week. After completion of training, subjects repeated pre-testing measurements in the exercise laboratory.
Measurements
On the first visit to the lab, weight and height were measured.
Body composition was determined using triceps and subscapular skinfolds measured in triplicate with a skinfold caliper
(Human Kinetics).
Prior to each exercise test, before data collection, each subject’s
79
revista
19.9.03
0:50
Página 80
facemask (8940 Series, Hans Rudolph, Inc., Kansas, MO) was
properly fitted and sealed with a gel (Hans Rudolph, Inc.) to
minimize any gas leaks. Subjects breathed through a flow
meter from which two sample lines transported expired air to a
metabolic measurement system (VMax 29, SensorMedics,
Yorba Linda, CA), which was calibrated for flow volume, VO2,
and VCO2 before each test. Subjects were given enough time to
familiarize themselves with the breathing apparatus to minimize non-physiological results.
During exercise testing and recovery periods, an electrocardiogram, as well as respiratory and metabolic variables (VE
(BTPS), VT (BTPS), RR, VO2 (STPD), and VCO2 (STPD)) were
continuously monitored. Ventilatory equivalent for O2
(VE/VO2), respiratory exchange ratio (RER = VCO2/VO2),
ventilatory equivalent for CO2 (VE/VCO2), and oxygen pulse
(O2P = VO2/HR) were derived from the above variables. Blood
pressure was measured during the maximal treadmill protocol
with an automated cuff (STBP-780, Colin).
80
ogist as a means of monitoring intensity. Verbal encouragement
was also provided throughout training.
Data Processing and Analysis
From smooth breath-by-breath data, averages were calculated
for exercise variables measured during the last 20 seconds of
warm-up and exercise. Paired Student’s t-tests were used to
compare pre-training and post-training measurements.
Statistical significance was taken at the p < 0.05 level for all
tests. Values that are displayed in results are presented as
mean ± standard deviation (SD).
Results
Anthropometrics
Except for height and body surface area (BSA), no significant
differences were found when comparing anthropometrics
before and after training (Table 1).
Exercise Testing Protocols
On the first day, subjects performed a maximal exercise test on
a motor-driven treadmill. After a 3-min warm-up at 1 mph and
0% grade, the treadmill speed and slope were increased to 1.7
mph and 10% grade. Following the initial work rate change,
treadmill speed and grade increased every 6-sec until exhaustion (DiBella). Exercise was followed by a 3-min active recovery stage. Subjects were told not to grip the handrails during
the test, except to hold on during the increase in speed from
walking to running if necessary. On the second day, subjects
performed a submaximal exercise test at the speed and grade
which corresponded to 75% VO2max from the maximal treadmill test. After the 8-week conditioning program, subjects
repeated these exercise tests.
During the maximal exercise tests, the following criteria were
used as indicators of a maximal effort: (a) HR >85 % of predicted peak heart rate, (b) RER > 1.0, and (c) the achievement of a VO2 plateau. Attainment of at least two of these criteria was required in order for an exercise test to be considered maximal.
During the submaximal tests, a steady-state was assumed to be
achieved when VE, VO2, and HR did not change more than 5
% for a 90-second period.
Peak Responses to Maximal Treadmill Test
Relative VO2peak values for pre-training (44.8 ± 6.1) and posttraining (46.2 ± 4.5 mL·kg-1·min-1 ) were not different.
However, there were significant differences in absolute peak
VO2, RER, and VE/VO2 (Table 2). There were also significant
improvements in exercised time (Figure 1), speed, and slope
when pre- and post-training tests were compared. The maximum speed increased from 5.1 ± 1.3 to 5.8 ± 0.3 mph (p
>0.005) and the maximum slope increased from 18.7 ± 1.2 to
21.4 ± 1.2 % grade (p > 0.001).
High-Intensity Training Program
Subjects were engaged in training 3 days/week (1 hr/day) for 8
weeks. All subjects wore a HR monitor (Polar Beat, Polar
USA), so that they could individually monitor their HR and
maintain the prescribed intensity. Subjects then warmed up
and stretched for 10 minutes. After the warm up, subjects
began a 10-minute bout of running around a quarter-mile cinder track. During the 10-minute running bouts there were 2minute intervals of high intensity running interspersed with 2minute intervals of moderate intensity running totaling 3 “fast”
intervals and 2 “moderate” intervals. After the first running
bout subjects participated in soccer drills and scrimmages for
20 minutes. In the last 10 minutes, subjects repeated the running phase previously described. Each training session ended
with a recovery period of jogging and stretching.
Subjects were instructed to maintain their HR in a range of 8595 % of their maximal HR as determined from pre-training
exercise testing. During running bouts subjects were frequently
asked about their heart rates by a supervising exercise physiol-
Table 2: Peak responses to maximal treadmill tests
Values are means ± SD; n, no. of subjects; *, p >0.05; oxygen uptake,
VO2; carbon dioxide output, VCO2; heart rate, HR; oxygen pulse,
O2-pulse; minute ventilation, VE; tidal volume, VT; respiratory rate,
RR; respiratory exchange ratio, RER; ventilatory equivalent for
oxygen; VE/VO2; ventilatory equivalent for carbon dioxide, VE/VCO2.
Table 1: Anthropometric characteristics of girls before and after training
Values are means ± SD; n, no. of subjects; BM, body mass; BSA,
body surface area; BMI, body mass index; LBM, lean body mass. *,
p >0.05; **, p > 0.01.
revista
19.9.03
0:50
Página 81
Time to exhaustion and relative efficiency were significantly
different before and after training (Fig. 1). When time to
exhaustion was utilized in order to estimate peak power
(Foster), significant improvements were detected (Fig. 2).
Table 4: Exercise variables during 75% VO2max before and after training
Values are means ± SD; n, no. of subjects; **, p < 0.01.
Fig. 1: Exercise time to exhaustion and change in relative efficiency
Values are means ± SD; n, no. of subjects; ****, p >0.0001.
Fig. 2: Pre- and post-training estimated peak power
Lactate Threshold
There were significant changes in LT as a result of training
when expressed in terms of percent of VO2max, percent of predicted VO2max, absolute and body mass-relative VO2, and VE
(Table 3).
Table 3: Lactate threshold changes with training
Values are means ± SD; n, no. of subjects; *, p<0.05; ***, p<0.001.
Submaximal Exercise Parameters
With the exception of HR there were no significant differences in
any exercise variables when comparing girls’ pre- and post-training values at an intensity of 75 % VO2max, (Table 4). Submaximal
HR was significantly lower following the training program.
Cardiovascular training studies in adults are numerous.
However, there is little research on high-intensity training in
youth, especially with girls. Determining specific exercise programs that may be beneficial to children rather than relying on
unexamined assumptions and adult-based training research, is
imperative (Pate and Ward). Therefore, the intent of this
study was to determine the physiological adaptations of a
high-intensity conditioning program on healthy, pre-pubertal,
female soccer players.
Several clearly positive training effects were observed as a
result of the current exercise program. Time to exhaustion during a maximal exercise test increased significantly (29.5 %)
after training while VO2max did not. This indicates an improvement in relative efficiency in that subjects exercised longer
(therefore reaching faster speeds and higher grades) before
reaching their maximal aerobic capacity (same VO2max). While
absolute VO2max did significantly increase by 6.5 %, there was
no change when changes in body mass were considered to
VO2max (44.8 to 46.2 mL·kg·min-1). Lactate threshold, which is
believed to be a sensitive indicator of training (Wasserman,
Mahon) increased by 17.6 % (from 51% to 60 % of VO2max),
indicating an improvement in cardiorespiratory fitness. With
regard to submaximal indices, steady-state HR decreased significantly by 10 bpm during a treadmill test at a work rate of
75% Vo2max after training. While it may at first be discouraging
that subjects did not significantly improve their VO2max, Pate
and Ward note that submaximal HR is a more sensitive indicator of training adaptation than VO2max (Pate and Ward). A substantial physiological training effect (such as improved VO2max)
is normally seen in adults after 5-10 weeks of training
(Casaburi). However, there is no consensus on the training
time needed to see improvements in VO2max in children (Pate
and Ward). The 8-week duration of this training program was
well above that of other studies reporting significant improvements in VO2max in children after a 6-week (Massicotte and
MacNab) and even a 4-week program (Docherty). On the
other hand, it is possible that even if the duration of the current program greatly exceeded 8-weeks, there still may not
have been increases in VO2max since some quite long studies
(14 months of training) have been unable to improve subjects’
VO2max values (Yoshida).
While performance measures were not completed in this study,
it may be anecdotally to note that the team of which most of
these girls were members had lost all of its games in the previ-
81
revista
19.9.03
0:50
Página 82
ous year; however, in the season during which the conditioning
program was conducted they only loss one game! This is not a
specific performance parameter measurement, however, it clearly points toward an improvement in performance in a sport that
demands excellent aerobic and anaerobic fitness levels.
The conditioning program was well attended, as each girl
missed at most two days of training, resulting in 92 % adherence. However, one of the eight subjects who participated in
the training needed to be eliminated from data analysis due to
low effort level during exercise sessions. She was not even able
to complete post-training exercise testing.
Having many of the subjects coming from the same soccer team
was advantageous in that the girls all knew each other and
already knew how to work together. Additionally, there were
girls who prefer both offensive and defensive positions resulting
in successful drills and scrimmaging. There was a positive competitive spirit evident since the subjects knew each other.
In conclusion, there were clearly some physiological adaptations to the training observed during both submaximal and
maximal exercise tests. These included increased maximal
exercise time and LT, as well as decreased submaximal HR for a
given intensity. However, this mode of training did not provide
the usual observation of increased VO2max with training when
there is an appropriate stimulus (Rowland).
While spot-checking method for monitoring HR worked quite
well, as subjects were almost always within the appropriate target HR range during exercise when periodically asked to read
their HR monitor, it may be beneficial in future studies to use
HR monitors that are capable of recording HR throughout
training, so that actual intensities achieved according to HR
may be verified quantitatively. Also, relating performance testing to physiological improvements will be a useful piece of
information to add to the body of knowledge of exercise training and performance development in children and adolescents.
Victoria University, CRESS Melbourne, Australia
References
Bailey RC, Olson J, Pepper Sl, Barstow TJ, Porszsasz J, Cooper DM
(1995). Med Sci Sports Exerc 27:1033-1041
Williams CA, Armstrong N, Powell J (2000). Aerobic responses of prepubertal boys to two modes of training. 34:168-173
Canadian Society for Exercise Physiology (1994). PAR-Q and you.
Gloucester, Ontario 1-2.
DiBella II JA, Johnson EM, and Cabrera ME (2002). Pediatric
Exercise Science 14(4): 391-400
Foster C, Jackson AS, Pollock ML, et al. (1984). Am Heart J
107:1229-1234
Pate RR, Ward DS (1989). Advances in Sports Med Fit 3::37-55
Wasserman K, Whipp BJ, Koyal SN, Beaver WL (1973). J Appl
Physiol 35:236-243
Mahon AD, Vaccaro P (1989). Med Sci Sports Exerc 21:425-431
Massicotte DR, MacNab RBJ (1974). Med Sci Sports Exerc 6:242-246
Yoshida T, Ishiko I, Muraoka I (1980). Int J Sports Med 1:91-94
Docherty D, Wenger HA, Collis ML (1987). J Appl Physiol 19:389-392
Rowland TW (1992).Can J Sport Sci 17: 259-263
CARDIOVASCULAR RESPONSE TO ENDURANCE TRAINING
IN CHILDREN IS NOT GENDER DEPENDENT
PHYSIOLOGICAL DEMANDS OF PLAYING FOUR GAMES
IN ONE DAY ON JUNIOR RUGBY UNION TOURNAMENT PLAYERS
Carlson John, Naughton Geraldine, Searl John
82
Keywords: rugby, physiology, elite junior
Australian Rugby Union strives to provide safe and optimal
playing environments for young participants. Due to the highly
competitive nature of National Championships they may create
unprecedented stress on Under 18 players, but the physiological stresses of a tournament are poorly understood. This study
compiled a physiological profile of players and described several fatigue-related factors across four, 20 minute games of rugby
in 45 adolescent males in a one-day tournament. Measures
included body mass changes at the start and end of the day,
and pre and post game changes in ratings of leg muscle soreness, perceived exertion and repeated sprint times and blood
lactate concentrations. Coaches/managers were asked to record
the amount of playing time of participants and injuries.
Descriptive characteristics revealed a mean age (17.2 ± 95%
CI 0.2 yr), body mass change over the day (0.2 ± 0.14 kg)
and mean change in blood lactate concentration following pre
and post game repeated sprints (2.89 ± 1.34 mM). Ratings of
leg muscle soreness and perceived exertion increased with
games played and playing time correlated with rating of perceived exertion and change in lactate following games. Total
mean playing time was 36 ± 6 minutes, and seven of the ten
injuries reported in players occurred in Games 3 and 4. Further
development of a model for monitoring markers of psychological and physiological fatigue under highly competitive situations will provide empirical data on which to base decisions
regarding f demands of junior rugby players in terms of games
times and the number of competitive games to be played in
one day or over a period of days.
Obert Philippe1, Mandigout Stephane2, Vinet Agnes1,
N’Guyen Long Dang2, Stecken François2, Lecoq Anne-Marie2
1 Laboratory of Cardiovascular Physiology,
University of Avignon, France
2 Faculty of Sport Sciences and Physical Education,
University of Orléans, France
Keywords: Training, cardiac, echocardiography
Introduction
In healthy children, aerobic training increases maximal O2
uptake (VO2max) but magnitude of improvement appears to be
limited when compared to adults, even if training stimuli or
initial physical fitness are taken into account [Rowland and
Boyajian, 1995]. Mechanisms (i.e. central and/or peripheral
adaptations) by which VO2max increases in children after training are not yet fully elucidated. Cross-sectional studies have
reported higher VO2max in endurance trained children because
of higher maximal stroke volume (SVmax) only [Nottin and al,
2002]. However, whether these superior cardiac functional
capacities reflect the effect of training or are simply due to
genetic factors can not be easily determined from such studies.
Only one longitudinal study has evaluated the effect of an aero-
revista
19.9.03
0:50
Página 83
bic training program on the response of the cardiovascular system during maximal exercise in boys [Eriksson and Koch,
1973]. The latter confirmed an increase in VO2max as a result of
training induced by an increase in SVmax only. Mechanisms
potentially responsible for SVmax improvement were however
not investigated. Moreover this study involved boys only which
does not therefore allow to determine whether gender influences cardiovascular response to training. This is however valuable since lower VO2max in girls than in boys are frequently
reported in the literature [Armstrong et al, 1991]. The aim of
the present study was to determine in healthy children the
effect of a well-controlled endurance training program on cardiac function at maximal exercise and to define whether gender
affects the training-induced cardiovascular response. The contribution of factors potentially involved in those adaptations
such as cardiac dimensions and diastolic and systolic functions
was also investigated.
Methods
Thirty-five l0-11 year old children took part in this study : 19
children (10 girls and 9 boys) were assigned to participate in a
13 week endurance training program (3x1h/week, intensity:
>80% HRmax) and 16 (7 girls and 9 boys) served as a control
group. At first, an anthropometric evaluation (height, weight,
and lean body mass by dual X ray absorptiometry), as well as
M-mode, 2-dimensional and pulsed-wave Doppler analyses
(Diasonics Vingmed CFM-750 ultrasound imaging system,
incorporating a 3.5 MHz annular array transducer) were conducted at rest in the supine position. Cardiac dimensions (Left
ventricular end-diastolic and end-systolic dimensions, LVEDd
and LVEDs, respectively; posterior wall and interventricular
septal thicknesses, PWT and ST, respectively, left ventricular
mass, LVM) as well as systolic (LV shortening fraction SF) and
diastolic (peak velocity of early diastolic rapid inflow , peak E;
and of atrial contraction filling, peak A; ratio peak E / peak A)
functions were evaluated. Then, cardiovascular (stroke volume
and cardiac output by Doppler echocardiography, SV and Q,
respectively; and systemic vascular resistance, SVR) and bioenergetic (VO2) data were monitored during an upright maximal
exercise test conducted on a cycle ergometer.
Results
The training program led to a rise in VO2max, brought about
however only by an increase in SVmax in both genders.
Moreover, boys increased their VO2max to a greater extent than
girls (boys: +15%; girls: +9%) only because of a higher SVmax
improvement (boys: +15%; girls: +11%). No alterations were
noticed in the SV pattern from rest to maximal exercise (values
shifted upwards after training), indicating that the increase in
SVrest was a key factor in the improvement of SVmax and thus
VO2max. Regarding resting echocardiographic data, an increase
in LVEDd, concomitant with an improvement in diastolic function (i.e. increase in peak E), were observed after training and
constituted an essential element in the rise in VO2max after
training in these children. Moreover, during maximal exercise,
a decrease in SVRmax, was noticed which could also have play
an important role in the increase in VO2max. Highly significant
correlations were found between percent variation after training in VO2max and Qmax (p<0.001), SVmax (p<0.001), SVrest
(p<0.01), LVEDd (p<0.001) and SVRmax (p<0.01). For both
groups and regardless of time intervention, boys had significantly higher VO2max, Qmax, SVmax, LVEDd, PWT and ST, and
LVM than girls. They had also lower SVmax than girls. There
were no gender differences for all the other variables.
The major finding of the present study was that in healthy children, VO2max increases after aerobic training as a result of an
increase in SVmax only. Such an adaptive process was found,
and this is a new finding, irrespective of gender. We are
unaware of previous paediatric studies dealing with the effect
of training on cardiac function according to gender. Our results
were consistent with, to our knowledge, the only one longitudinal study which investigated in boys the effect of aerobic
training on the Fick equation parameters and reported that
SVmax was the only parameter that was modified after training
[Eriksson and Koch, 1973]. SV depends on a complex interplay
of many factors such as intrinsic left ventricular relaxation and
contractility properties, internal chamber dimension, pre-load
and after-load. In the present study, similar mechanisms
including increase in pre-load (i.e. blood volume) and decrease
in after-load (SVR) conditions as well as cardiac enlargement
(LVEDd) seem to be involved in both boys and girls in order to
explain SV improvement. These results have important health
implications because they shows that a chronically instrumented physical exercise program in children results essentially in
central cardiovascular adaptations.
References
Rowland TW, Boyajian, A (1995). Pediatrics, 96: 654-8.
Nottin S, Vinet A, Stecken F, N’Guyen LD, Ounissi F, Lecoq AM,
Obert P (2002). Acta Physiol Scand, 175 : 85-92.
Eriksson BO, Koch G. (1973). Acta Physiol Scand 1973; 87:27-39.
Armstrong N, Williams J. (1991). Eur J Appl Physiol, 62:369-375
LEFT VENTRICULAR FUNCTION IN ENDURANCE-TRAINED
CHILDREN BY TISSUE DOPPLER IMAGING
Nottin Stephane1, Nguyen Long-Dang2, Terbah Mohamed2,
Obert Philippe1
1
Laboratory of Cardio-vascular Adaptations to Exercise,
Faculty of Sciences, Avignon, France
2 Cardiology Department, Regional Hospital Center, Orléans, France
Keywords: left ventricular relaxation properties, trained children, tissue
doppler imaging
Introduction
In young adults and children, the enhanced cardiac performance induced by endurance training is mainly due to the
increase in left ventricular (LV) filling since LV systolic function is not altered. In adults, it is well established that the
increase in LV filling induced by endurance-training results
from several factors including in particular a cardiac hypertrophy and an increase in preload due to plasma expansion.
However, whether LV relaxation properties is increased by
endurance-training is controversial (Caso et al., 2000 ;
Schmidt-Truckssass et al., 2001). In children, the underlying
mechanisms responsible for the higher LV filling consecutive to
endurance-training remain uncertain (Obert et al.,2001).
Compared to adults, endurance-trained children exhibited only
83
revista
19.9.03
0:50
Página 84
moderate increase in LV internal diameter, without changes in
interventricular septum and posterior wall thickness. Moreover,
whether LV preload and/or LV relaxation properties are
increased by endurance-training in children is unknown.
Recently, a new Doppler application, based on tissue Doppler
imaging (TDI) has been developed. This method provides additional information on LV relaxation properties by the measurement of LV regional wall motions. By using this new echocardiographic tool, the aim of the present study was to test
whether LV relaxation properties are increased by training in
prepubertal children and young adults.
Methods
Standard echocardiography (LV morphology and function) and
tissue Doppler imaging (LV relaxation properties) were
assessed at rest in 14 adult cyclists and triathletes, 13 agematched sedentary controls, 12 child cyclists and 11 untrained
boys. Standard Doppler echocardiography and TDI measurements were performed with the subjects in a partial left decubitus position using an HDI 5000 system (Phillips Ultrasound
system). Doppler echocardiographic and TDI tracing were
recorded digitally on hard drive for further analysis and all
measurements were averaged on 3 to 5 measures obtained during end-expiratory of normal respiration. Standard echocardiograms consisted of 2-dimensional, M-Mode and Doppler blood
flow measurements according to the recommendations of the
American Society of Echocardiography. Wall motion velocities
by TDI were assessed at the mitral annulus level, on the septal,
lateral, inferior and anterior walls, from 2- and 4-chambers
views. The pulsed TDI was characterized by the myocardial
systolic wave (Sm) and 2 diastolic waves (Early, Em and Atrial,
Am), expressed in cm.s-1. Peak velocity of Sm was used as systolic index, and Em, Am peak velocities and Em/Am ratio were
determined as diastolic measurements. Among these TDI diastolic measurements, Em peak velocity can be considered as a
good index of LV relaxation properties (Nagueh et al, 1997).
Each variable was compared between the 4 groups by using a
two-way analysis of variance (age group x training status).
When an overall difference was found at P<0.05, a post hoc
test of Fisher PLSD was performed.
Results
In adults, cyclists and triathletes exhibited both higher LV
internal diameter, wall thickness and mass. However, no effect
of training was obtained on Em peak velocities recorded at the
level of 4 walls of the mitral annulus, indicating that
endurance-training did not improve the rate of relaxation of
their myocardium. Moreover, no significant correlations were
obtained between LV filling and morphologic parameters,
showing that increased LV internal diameter was mainly due to
structural alterations. As opposed to adults, child cyclists had a
moderate increase in LV internal diameter without changes in
wall thickness. Significantly higher Em peak velocities were
obtained at the level of the septal, inferior and anterior walls of
the mitral annulus, indicating an increased rate of LV relaxation in child cyclists compared to untrained children.
Moreover, significant correlations were found between both LV
internal diameter and Em recorded at the inferior (P<0.05,
R=0.46) and the anterior (P<0.001, R=0.65) wall. SV was
correlated with inferior Em (P<0.05, R=0.43) and anterior Em
(P<0.01, R=0.54).
84
Discussion
In both children and adults, the present study confirmed the
better cardiac performance (i.e. higher SV) as a result of
endurance-training. The enhanced cardiac performance
observed in endurance-trained children as well as young adults
was mainly due to higher LV filling since no effect of training
were observed on all systolic parameters. Our results mainly
support that some mechanisms responsible for the increase in
resting LV filling after endurance-training are partially agerelated. In adults, the enhanced LV filling observed in our
trained subjects was indeed mainly related to their cardiac
hypertrophy, since neither LV relaxation properties, nor LV filling patterns accounted for differences in LV filling. In
endurance-trained children, the LV morphological response to
training was specific compared to that of adults, and included a
moderate increase in LV end-diastolic diameter without
changes in LV septal and posterior wall thickness. In children,
LV relaxation properties were improved in the trained group,
and correlated with LV internal diameter and SV, indicating
that they played a major role in the increase in LV filling.
However, in child cyclists, we could not exclude that LV filling
was also improved by increased preload due to plasma expansion, but this hypothesis needs further investigation since
effect of endurance training on blood volume has never been
investigated in children.
References
Caso PA, D’Andrea M (2000). Am J Cardiol. 85:1131-1136
Nagueh SF, Middleton KJ (1997) J Am Coll Cardiol. 30:1527-1533.
Obert P, Mandigout S. (2001) Int J Sports Med. 22:90-96.
Schmidt-Trucksass A, Schmid A. (2001) Med Sci Sports Exerc.
33:189-195
THE REPRODUCIBILITY OF BLOOD PRESSURE FOLLOWING
MAXIMAL EXERCISE IN 9-10 YEAR OLD CHILDREN
Middlebrooke Andrew1, Armstrong Neil2, Ball Claire1,
MacLeod Kenneth1 and Shore Angela1
1
Peninsula Medical School, Exeter, UK
Children’s Health and Exercise Research Centre,
University of Exeter, Exeter, UK
2
Keywords: blood pressure, reproducibility, exercise
Introduction
An exaggerated increase in systolic blood pressure in response
to acute exercise has been shown to be a stronger predictor of
the future development of hypertension1, stroke2 and cardiovascular events3 than resting measures of blood pressure and is
an independent predictor of mortality4. An early prediction of
increased cardiovascular risk in children is extremely attractive,
however there is a lack of evidence regarding the reproducibility of blood pressure measurements during exercise in children.
Therefore, the aim of the present study was to determine the
reproducibility of the blood pressure response to maximal exercise in 9-10 year old children.
Methods
Ten healthy children (5 boys and 5 girls) were recruited from a
revista
19.9.03
0:50
Página 85
local Exeter school (age 9.9 ± 0.3y; body mass 37.1 ± 8.8kg;
stature 1.39 ±0.07m). Systolic and diastolic blood pressure
(Phase IV) were measured using a manual mercury sphygmomanometer (Dekamet Mk3, Accoson Ltd, U.K.) and stethoscope (Litmann Class II S.E., 3M Healthcare, Germany) at the
site of the brachial artery at rest, immediately before and after
a continuous incremental exercise test to exhaustion on a cycle
ergometer (Lode Excalibur, Groningen, Netherlands) on three
separate occasions. Respiratory gases were measured on a
breath-by-breath basis throughout the test using an online
mass spectrometer (Morgan Medical EX-670, Morgan Medical,
Guildford, U.K.) and averaged over 15 seconds for analysis.
Heart rate was measured continuously using a 12-lead electrocardiogram system integrated with the mass spectrometer (PCECG1200, Norav Medical Ltd. Israel). The subject was judged
to have attained peak VO2 when two of the following criteria
had been satisfied; 1) heart rate within 10 b.min-1 of age-predicted maximum heart rate; 2) respiratory exchange ratio
greater than 1.0; 3) a plateau of VO2 values.
3.
4.
5.
6.
Results
A repeated measures analysis of variance demonstrated that
there was no significant difference in systolic or diastolic blood
pressure over the three test occasions, at rest, pre-exercise and
post-maximal exercise (Table 1). There was no significant difference in the change in blood pressure from rest to post-maximal exercise over the three test occasions (delta systolic: 36±11
v 30±11 v 33±10mmHg, p=0.481, delta diastolic: 7±10 v -1±12
v 9±6mmHg, p=0.1). The mean within-subject coefficient of
variation over the three trials for systolic blood pressure postmaximal exercise was 3.4% and for diastolic blood pressure
was 9.3%. There was no significant difference in peak VO2
between the three test occasions (Table 1).
Low cardiopulmonary fitness (VO2max), excessive body fatness
and a central pattern of fat accumulation are major risk factors
for cardiovascular morbidity and mortality. However, little is
known to what extent this is related to the effects of cardiopulmonary fitness and body fatness/fat distribution on atherosclerosis and arterial stiffness, the underlying mechanisms of cardiovascular impairment and mortality. Moreover, the time
course of these relationships needs to be elucidated. We therefore investigated the prospective relationship between levels of
fitness, fatness and fat distribution during adolescence (13-16
years) on the one hand, and indicators of pre-clinical atherosclerosis (i.e. carotid intima-media thickness - IMT) and large
artery stiffness (i.e. distensibility and compliance coefficients),
at the age of 36, on the other.
Arterial properties were assessed by non-invasive ultrasound
imaging. VO2max was measured with a maximal running text on
a treadmill with direct measurements of oxygen uptake. The
sum of 4 skinfolds (ΣSKF) was used as an estimate of total
body fatness, and the ratio between the subscapular+suprailiac
and the ΣSKF (SS/ΣSKF) as an estimate of central fat accumulation. Analyses consisted of 159 subjects (84 girls) and data
were analysed with multiple linear regression models.
After adjustment for smoking status, alcohol and nutrients
intake, physical activity, biological age and current height, adolescent VO2max were inversely associated with carotid IMT at
age 36 (β=-0.32, p=0.03), in men. Adolescent ΣSKF and
SS/ΣSKF were positively associated with carotid IMT at age 36
(β =0.32, p<0.01 and β =0.24, p=0.07), the latter in men
only. As far as arterial stiffness is concerned, only SS/ΣSKF
during adolescence was inversely associated with distensibility
(β =-0.14, p=0.07) and compliance (β =-0.19, p=0.01) of the
carotid artery. Further mutual adjustments of these relationships for VO2max, ΣSKF and SS/ΣSKF, and other risk factors
(cholesterol, blood pressure and resting heart rate) did not
change the strength of these associations.
We concluded that low cardiopulmonary fitness, excess body
fatness and in particular a central pattern of fat accumulation
during adolescence may me critical for the onset of atherosclerosis and arterial stiffness later in life. Therefore promotion of a more active lifestyle starting already during adolescence may be an important tool for the primary prevention of
cardiovascular disease.
Table 1. Systolic and diastolic blood pressure response at rest, pre-exercise and post-maximal exercise and peak VO2 over three test occasions.
These data suggest that systolic and diastolic blood pressure at
rest, pre-exercise and following maximal exercise are reproducible measures in 9-10 year old children. This is in contrast
to a previous finding in adults5. If associations between the
blood pressure response to exercise and cardiovascular events
in adults are common to children6, the blood pressure response
to exercise could potentially be used as a non-invasive marker
of cardiovascular risk at an early age.
References
1. Miyai N et al. (2000). J Am Coll Cardiol 36(5): 1626-31
2. Kurl S et al. (2001). Stroke 32(9): 2036-41
Moan A et al. (1995). Am J Hypertens 8: 268-275
Mundal R et al. (1994). Hypertension 24(1): 56-62
Sharabi Y et al. (2001). Am Heart J 141(6): 1014-7
Kavey RW et al. (1997). Am Heart J 133(2): 162-8
FITNESS, FATNESS AND FAT DISTRIBUTION DURING
ADOLESCENCE AND LARGE ARTERY PROPERTIES IN ADULTHOOD.
A PROSPECTIVE ANALYSIS WITHIN THE AMSTERDAM GROWTH
AND HEALTH LONGITUDINAL STUDY
Ferreira I, Twisk JWR, van Mechelen W, Kemper HCG,
Stehouwer CDA
Institute for Research in Extramural Medicine (EMGO) - VU
University Medical Center, The Netherlands
Keywords: cardiopulmonary fitness, body composition, arterial properties
85
revista
19.9.03
0:50
Página 86
COMPOSITION AND DENSITY OF FAT-FREE MASS
IN ADOLESCENT ATHLETES BASED ON A FIVE-COMPONENT
MOLECULAR MODEL OF BODY COMPOSITION:
COMPARISON WITH LOHMAN’S AGE-ADJUSTED MODELS
Sardinha Luís B, Silva Analiza M, Minderico Claudia
Exercise and Health Laboratory, Faculty of Human Movement,
Technical University of Lisbon, Portugal
Keywords: body composition, athletes, fat-free mass
Introduction
Estimates of body composition are used to assess nutritional
status, disease risk, and physical fitness and to separate the
body mass into metabolically active and inactive components 1.
In athletes, body composition measures are widely used to prescribe desirable body weights, to optimize competitive performance, and to assess the effects of training 2. In addiction,
there is an increased recognition of the need to measure body
composition during growth and puberty, as preadolescent and
adolescent years are a period of a rapid growth in the body fat
and non-fat compartments.
Traditional indirect methods for evaluating body composition
in humans, such as densitometry, hydrometry, and 40k spectrometry, are based on a two-component model in which it is
assumed that the body consists of fat and fat-free components
3. For example, densitometry assumes that body mass consists
of a fat mass component with a density of 0.9007 g/cm3 and a
fat-free mass (FFM) component with a density of 1.100 g/cc 4.
The FFM is assumed to be composed of 73.8% water with a
density of 0.9937 g/cc, 6.8% mineral with a density of 3.038
g/cc, and 19.4% protein with a density of 1.34 g/cc 5. However,
these assumptions may not be the most accurate in children
and adolescents because of the potential changes in the various
inherent assumptions of the 2C model during growth and maturation, such as changes in the hydration and the density of
FFM 6. In order to overcome these methodological limitations,
Lohman 6 developed age- and sex-specific constants to convert
body density into body fat (BF) in children, based on the existing data in children from birth to 10 years of age 7 and the
FFM composition of growing adolescents 7-9. Even though this
theoretical approach seems to improve the accuracy of BF prediction in children, it does not address the issue related with
body composition changes, namely FFM density and respective
fractions of water, protein, and mineral during growth and maturation in athletes.
Multi-compartment models such as the three-compartment
(3C), 4C, and the recently 5C molecular model 10, take into
account interindividual variability in the composition of FFM.
The 5C molecular model divides body weight into fat, water,
bone mineral, soft tissue mineral, and protein, and fewer
assumptions are considered in the composition of FFM by
accounting for variations in body water and mineral, which are
among the most variable components of FFM 11,12. Regarding
the recognized chemical immaturity in growing children, Wells
et al. 13, have used a 4C molecular model as the “gold standard” through which interindividual variability in the density
and hydration of FFM was evaluated, indicating that FFM density was significantly lower and hydration higher, than the
adult assumptions. Studies on some small groups of adults
bodybuilders athletes 14,15, male football players and female
86
swimmers have found systematic differences between estimates of %BF based on a 4C model and estimates from body
density 16, indicating that FFM density was different than 1.100
g/cc, whereas studies with athletes involved in other sports
have not 16-19.
Considering the inconsistence data on FFM density and composition in athletes and the required studies on an athletic
population during growth and maturation, the purpose of the
present study was twofold: to determine estimates of body
composition from a 5C model in which body density, water,
bone mineral, and soft tissue mineral were estimated in order
to analyse FFM composition and its implications on FFM density, and to determine whether Lohman’s 6 age- and sex-specific values for FFM density and composition are appropriate for
adolescent athletes.
Methods
Sample
A total of 32 girls and 45 boys, Caucasian, pubescent and postpubescent, volunteered for the study. Subjects were recruited
from several sports clubs and were involved in a variety of
sports (e.g. swimming, basketball, gymnastic, rugby and judo).
According to the regulations of the Ethical Committee of the
Faculty of Human Movement, Technical University of Lisbon,
all subjects were informed about the research design and
signed a consent form. All measurements were obtained with
subjects fasted overnight (≥ 12 h).
Maturation
Subjects were grouped by puberty stage of development, determined by self-assessment according to Tanner 20 stage and
adapted by Ross and Marfell-Jones 21. A self-evaluation
method, with figures, was used to identify the degree of development of the genital organs, breast and pubic pilosity.
Measurements of body composition
Measures of body volume assessed by air displacement plethysmography, bone mineral content by dual-energy x-ray absorptiometry (DXA) and total body water by deuterium dilution
were used to estimate %BF. Briefly, body volume was estimated
using the BOD POD® (Life Measurement Instruments,
Concord, CA) as described elsewhere 22,23. Bone mineral content was obtained by DXA (QDR-1500; Hologic, Waltham,
MA) from the whole body scans and converted to total body
bone mineral (as bone mineral content represents ashed bone)
by multiplying it by 1.0436 24. Total body water (TBW) was
assessed by the deuterium dilution technique using an isotope
ratio mass spectrometer (PDZ, Europa Scientific, UK). After a
completed 12 h fast, an initial urine sample was collected and
immediately administrated a deuterium oxide solution dose
(2H2O) of 0.1g/kg of body weight diluted in 150 mL of water.
After a 4h period new urine sample was collected. Urine was
prepared for 1H/2H analysis using the equilibration technique
of Prosser and Scrimgeour 25. The enrichments of equilibrated
local water standards were calibrated against SMOW (Standard
Mean Ocean Water). Based on delta SMOW, total body water
was estimated by Schoeller et al. 26 method, including a 4%
correction due to the recognized amount corresponding to deuterium dilution in other compartments.
The Wang et. al. 5C molecular model 10, was used as the reference method to estimate BF. Accordingly, BF was assessed with
the following equation:
revista
19.9.03
0:50
Página 87
BF (kg)=2.748xBV - 0.715xTBW + 1.129xMo
+ 1.222xMs - 2.051xBM
where BV is body volume (L), TBW is total body water (kg),
Mo is total-body bone mineral (kg), Ms is total-body soft tissue
mineral (kg) and BM is body mass (kg).
Statistical Analysis
Comparison of means was performed with a paired t-test.
Considering that FFM density and respective water, protein
and bone mineral fractions are age-dependent in Lohman’s
models, a one-sample t-test was used to assess if the differences between the selected variables from Lohman’s models
and the 5C model were different from zero at any given age.
Statistical significance was set as p < 0.05. The statistical
analysis was performed using the Statistical Package for the
Social Sciences (SPSS inc., version 10.0, Chicago, IL).
Results
Table 1 depicts the means and standard deviations values of
FFM density and composition, namely water, bone mineral,
soft tissue mineral and protein.
Table 1 – Means and standard deviations values for the selected variables.
1
2
Differences between FFM density estimated by the 5C model
and by Lohman’s age-adjusted values (p<0.001)
Differences between FFM composition estimated by the 5C model
and by Lohman’s age-adjusted values (p<0.001)
Differences between FFM hydration were different (p<0.05)
in boys and girls (1.88 vs. 4.28%), respectively. Differences
between FFM mineralization (0.33 vs. 0.33 %), and FFM
residual/protein fraction (2.21 vs. 3.96 %) were also different
(p<0.05) in boys and girls, respectively. Finally, FFM density
was higher than Lohman’s age-adjusted models 6 and differed
(p<0.05) by 0.004 and 0.012 g/cc, in boys and girls, respectively. FFM density was underestimated (p<0.05) by
Lohman’s models 6, due to the lower water fraction and the
higher residual/protein fraction, which has an assumed
greater density than water (1.34 vs. 0.994 g/cc). The molecular composition of the FFM, water, total body mineral, and
protein differed from Lohman’s age-adjusted constants 6. The
implications of the FFM density and composition on %BF are
shown in Figure 2.
Figure 1 – For boys and girls, means and standard deviations values
of %BF estimated by the 5C model and %BF2C-Lohman. *p<0.001
In boys, using Lohman’s age-adjusted models 6 and the 5C
molecular model yielded different (p<0.001) %BF values (11.6
± 5.5 vs 13.1 ± 4.9). Similar differences were found in girls
when these two models were used (15.8 ± 7.3 vs 19.8 ± 7.0).
Therefore, as indicated in Figure 1, %BF was underestimated
in relation to the reference 5C model when Lohman’s ageadjusted models 6were used in both genders.
There is little information regarding exercise effects on FFM
density and respective compartments as, so far, few studies
have defined the variability in FFM density among different
athletic groups 14-19. In addiction these few studies were conducted in adult athletes and presented controversial results.
The present data represents the first estimated values for FFM
composition and density in adolescent athletes using a robust
5C model. The mean values for boys matched closely to the
adults assumed FFM density (1.100 g/cc), but the mean values
for the female young athletes were significantly greater, though
the composition of the FFM in each of these groups differed
somewhat from the assumed values (73.8% for water/FFM;
6.8% for mineral/FFM and 19.4% for protein/FFM) 5.
Conversely, FFM density from the present data was higher than
the results obtained on non-athlete prepubescent children evaluated with a 4C molecular model in the study of Wells et al. 13
(1.102 ± 0.006 vs. 1.086 ± 0.007). Concerning the higher
FFM density presented in the female adolescent sample, similar results were found in the female adult gymnasts from the
study of Prior et al. 16, whereas female adults swimmers from
the referred study had a significantly less FFM density than
1.100 g/cc. It is important to note that in the present work,
fourteen girls were gymnasts, fourteen were basketball players
and the remained four were swimmers and judo athletes. In
line with the general findings of the current study, Penn et al.
17, Withers et al. 18, and Arngrímsson et al 19 using a sample of
male and female runners showed that no differences were
found between FFM density and the assumed value 1.100 g/cc.
On the other hand, Modlesky et al. 14 and Withers et al. 15
using a sample with male bodybuilders, concluded that
increased muscle development in the athletes may further
decrease FFM density, primarily due to the higher water fraction and secondarily to the lower mineral and protein fractions
of the FFM than the values found in men with average muscu-
87
revista
19.9.03
0:50
Página 88
loskeletal development. According to these studies, skeletal
muscle hypertrophy appears to increase disproportionately the
water fraction of the FFM, which dilutes the mineral and protein fractions 14. As suggested by Prior et al. 16, these findings
indicate that the FFM density may be higher or lower than the
assumed values for adults and that generalization across athletes in different sports is not appropriate.
Concerning the use of the age-adjusted constants for changes
in the composition and density of FFM developed by Lohman 6,
lower values for FFM density were obtained compared with the
FFM composition and density obtained by the reference
method. The inability to reproduce Lohman’s models 6 indicates that the values for the density of FFM were not appropriate for young athletes. These differences may be explained by
the fact that the water fraction in the current study was lower
and total mineral (bone mineral plus soft tissue mineral) and
protein fractions were higher when compared with the
Lohman’s age-adjusted values 6. Consequently, the relative contribution of the protein and mineral fractions, which have a
higher density than water (respectively, 1.34 g/cc and 2.982
g/cc vs. 0.9937 g/cc) may justify the higher FFM density found
in the present study compared with Lohman’s age-adjusted
constants 6 for both genders. Moreover, these findings may justify the significant underestimation of %BF when body density
from Lohman’s 2C model 6 was used.
In conclusion, these results suggest that some caution should
be taken when using Lohman’s age-adjusted models 6, which
were developed on a sample of non-athlete children and adolescents, to estimate FFM composition in athletes during
growth and maturation. Furthermore, more research is needed
with young athletes performing specific sports to determine
whether FFM density is affected by muscularity or musculoskeletal development. Since assumed constants, as well as
FFM hydration, are the cornerstones of several body composition methods, further study is needed to identify relatively constant relationships between FFM components at any given age
in growing athletes.
References
1. Forbes, G.B. (1987) Human body composition: Growth, aging,
nutrition, and activity., Springer-Verlag
2. Sinning, W.E. (1996) Body composition in athletes. In Human
Body Composition (Roche, A.F. et al., eds.), pp. 257-274, Human
Kinetics Publishers
3. Siri, W.E., ed. (1961) Body composition from fluid spaces and density: Analysis of method, National Academy of Sciences
4. Going, S.B. (1996) Densitometry. In Human body composition
(Roche, A.F. et al., eds.), pp. 3-23, Human Kinetics Publishers
5. Brozek, J., Grande, F.& Anderson, J.T. (1963) Densitometry analysis of body composition: Revision of some quantitative assumptions.
Annals of the New York Academy of Sciences 110, 113-140
6. Lohman, T. (1989) Assessment of body composition in children.
Pediatr. Exerc. Sci. 1, 19-30
7. Fomom, S.J. et al. (1982) Body composition of reference children
from birth to age 10 years. Am J Clin Nutr 35 (5 Suppl), 1169-1175.
8. Haschke, F. (1983) Body composition of adolescent males. Acta
Paediatr Scand (307 (suppl)), 1-20
9. Boileau, R.A. et al. (1984) Hydration of the fat-free body in children during maturation. Hum Biol 56 (4), 651-666.
10. Wang, Z. et al. (2002) Multicomponent methods: evaluation of
new and traditional soft tissue mineral models by in vivo neutron activation analysis. Am J Clin Nutr 76 (5), 968-974
88
11. Bakker, H.K. and Struikenkamp, R.S. (1977) Biological variability and lean body mass estimates. Hum Biol 49 (2), 187-202
12. Lohman, T.G. (1992) Advances in body composition assessment,
Human Kinetics Publishers
13. Wells, J.C. et al. (1999) Four-component model of body composition in children: density and hydration of fat-free mass and comparison
with simpler models. Am J Clin Nutr 69 (5), 904-912.
14. Modlesky, C.M. et al. (1996) Density of the fat-free mass and
estimates of body composition in male weight trainers. Journal of
Applied Physiology 80 (6), 2085-2096
15. Withers, R.T. et al. (1997) Body composition changes in elite male
bodybuilders during preparation for competition. Aust J Sci Med Sport
29 (1), 11-16
16. Prior, B.M. et al. (2001) Muscularity and the density of the fatfree mass in athletes. J Appl Physiol 90 (4), 1523-1531
17. Penn, I.W. et al. (1994) Body composition and two-compartment
model assumptions in male long distance runners. Med Sci Sports
Exerc 26 (3), 392-397
18. Withers, R.T. et al. (1998) Comparisons of two-, three-, and fourcompartment models of body composition analysis in men and women.
J Appl Physiol 85 (1), 238-245
19. Arngrimsson, S. et al. (2000) Validation of body composition estimates in male and female distance runners using estimates from a fourcomponent model. Am J Human Biol 12 (3), 301-314
20. Tanner, J.M. (1962) Growth and adolescence, Blackwell Scientific
21. Ross, W.D. and Marfell-Jones, M.J. (1991) Kinanthropometry. In
Phsysiological testing of the high-performance athlete (MacDougall,
J.D. et al., eds.), pp. 224-305, Human Kinetics Publishers
22. Dempster, P. and Aitkens, S. (1995) A new air displacement
method for the determination of human body composition. Med Sci
Sports Exerc 27 (12), 1692-1697
23. McCrory, M.A. et al. (1995) Evaluation of a new air displacement
plethysmograph for measuring human body composition. Med Sci
Sports Exerc 27 (12), 1686-1691
24. Heymsfield, S.B. et al. (1990) Body composition of humans: comparison of two improved four-compartment models that differ in
expense, technical complexity, and radiation exposure. Am J Clin Nutr
52 (1), 52-58.
25. Prosser, S.J. and Scrimgeour, C.M. (1995) High-Precision
Determination of 2H/1H in H2 and H2O by Continuous-Flow Isotope
Ratio Mass Spectrometry. Anal Chem 67 (13(1)), 1992-1997
26. Schoeller, D.A. et al. (1980) Total body water measurement in
humans with 18O and 2H labeled water. Am J Clin Nutr 33, 26862693
BODY COMPOSITION AND CARDIORESPIRATORY FITNESS
IN CHILDREN AND ADOLESCENTS
Santa-Clara Helena, Ornelas Rui, Sardinha Luís B
Exercise and Health Laboratory, Faculty of Human Movement,
Keywords: body composition; cardiorespiratory fitness; children;
adolescents
Introdution
The peak VO2 of children and adolescents has been well documented and, data demonstrate a progressive, linear increase in
peak VO2 with chronological age in both genders. Mean value for
revista
19.9.03
0:50
Página 89
VO2peak increase from about 1.0 L/min at age 6 years in all children to 2.0 and 2.8 L/min for girls and boys, respectively, at 15
years of age, and mean values for boys exceed those of girls at all
ages (Rowland, 1996). When VO2peak is expressed relative to
body mass, with age different patterns of change occurs.
However, using a log-linear scaling model, Armstrong et al.
(1998) had demonstrated in 12-yr-old boys and girls a significant
effect of maturation on peak VO2 independent of body mass.
More than total body mass, differences in body composition
may partially explain gender differences in weight relative
VO2max, since males have a greater lean body mass than girls
even before puberty (Rowland, 1996). Several studies have
demonstrated gender differences at all ages when VO2max values are related to lean body mass with the greater values to the
boys (Anderson et al., 1974; Kemper et al., 1989; Rutenfranz et
al., 1981). This study was designed to analyse the influence of
total lean mass (TLM) and leg lean mass (LLM) on relative
expression of peak oxygen uptake (VO2peak) in healthy
Portuguese children and adolescents.
Methods
Children were 445 (212 girls - 9.7±0.32 yrs; and 234 boys 9.7±0.33 yrs), and adolescents were 120 (58 girls - 15.7±0.3
yrs; and 62 boys - 15.6±0.3 yrs). Cardiorespiratory fitness,
defined as maximal power output per kilogram (Wmax. kg-1),
was assessed in a cycle ergometer test. The subjects performed
a maximal graded exercise test on an electronically braked cycle
ergometer. Initial and incremental workloads were 20 W for
children weighing less than 30 kg and 25 W for children
weighing 30 kg or more. For adolescent girls and boys the initial and incremental workloads were 40 W and 50 W, respectively. The workload increased every 3 minutes. Heart rate was
controlled continuously (Polar Vantage, Finland) throughout
the test until subject could no longer continue, and the criteria
defined for maximal effort was heart rate ≥ 185 beat per
minute. The cycle ergometer was electronically calibrated once
every test day and mechanically calibrated after being moved.
The equation (12*Wmax+5*weight)/weight was used to estimate VO2peak relative to the weight of total body mass, TLM
and LLM. Total body scans were performed by dual-energy xray absorptiometry (DXA) and analysed using an extended
analysis program for body composition (model QDR-1500
Hologic, pencil beam, software version 5.67), to determinate
total body mass, TLM and LLM. The same technician positioned the subjects, performed the scans, and completed the
scan analysis according to the operator’s manual using the
standard analysis protocol. Quality assurance tests were performed each morning of assessment. Descriptive statistics were
used for presentation of the data. Group differences were
assessed by two-way analysis of variance (ANOVA). Statistical
significance was set at p<0.05.
Results
Subject’s physical characteristics and peak exercise data are
presented in Table 1. Boys had higher values of TLM and LLM
(p<0.001) than girls in all ages. In children, no differences
were found between boys and girls in stature and total body
mass. Adolescents boys were taller (p<0.001) and heavier
(p<0.01) than girls. As compared with children, adolescents
boys and girls had higher values of total body mass, lean mass
and legs mass (p<0.001).
Table 1. Mean values of studied variables
Values are mean ± SD. VO2peak peak oxygen uptake; TLM,
total lean mass, LLM, legs lean mass. * adolescents had higher values
than children in both genders (p<0.05).** children:
boys had higher values than girls (p<0.001). # adolescents:
boys hah higher values than girls (p<0.01).
Maximal power (watts), VO2peak relative to total body mass,
TLM and LLM were different (p<0.05) between children and
adolescents and between both genders (p<0.001). The difference between children and adolescent boys was 23%, 12%, and
2% when VO2peak was expressed relative to total body mass
(43.94±7.84 vs.53.95±7.36 mL/kg/min p<0.001), TLM
(58.11±7.94 vs.65.29±6.41 mL /kg of TLM/min, p<0.001) and
LLM (194.03±27.55 vs.196.85±19.75 mL/kg of LLM/min,
p<0.05), respectively. In girls the differences between children
and adolescents for the same variables were 1% (37.72± 6.59
vs. 37.96± 6.73 mL/kg/min, p<0.01), 5% (54.16±6.29 vs.
56.87±7.12 mL /kg of TLM/min, p<0.01), and 5%
(181.08±23.33 vs. 190.06±27.53 mL/kg of LLM/min, p<0.05).
Cardiorespiratory differences between children and adolescent
boys tend to decrease when total and regional functional mass
such as TLM and LLM were considered. These results suggest
that, differences in cardiorespiratory fitness between boys and
girls during growth and development are largely dependent on
TLM and LLM. Since differences in cardiorespiratory fitness
between girls and boys were diminished relative to LLM, these
data emphasize that differences in cardiovascular fitness
between boys and girls were largely attributable to differences
in body composition.
References
Andersen KL, Seliger V, Rutenfranz J, Mocelin R (1974). Eur J Appl
Physiol 33:177-195
Armstrong N, Welsman JR, Kirby BJ (1998). Med Sci Sports Exerc
30: 165-169
Kemper HC, Verschuur R, De Mey L (1989). Pediatr Exerc Science 1:
257-270
Rowland TW (1996). Developmental exercise physiology
Rutenfranz F, Andersen KL, Seliger V, Klimmer F, Berndt I, Ruppel M
(1981). Eur J Pediatr 136:123-133
IMPACT OF OBESITY AND DOWN SYNDROME ON MAXIMAL HEART
RATE AND WORK CAPACITY IN YOUTH WITH MENTAL RETARDATION
Fernhall Bo1, Pitetti Ken2, Guerra Myriam3
1
Exercise Science Department, Syracuse University, Syracuse, NY, USA
Physical Therapy Department, Wichita State University, Wichita,
KS, USA
2
89
revista
19.9.03
0:50
Página 90
3 Physical Activity and Sports Sciences, Fundació Blanquerna,
University Ramon Llull, Barcelona, Spain
Keywords: heart rate, obesity, Down syndrome
Introduction
Individuals with mental retardation (MR) have low physical
work capacity and thus low aerobic capacity, regardless of the
form of testing (5). Both laboratory and field based studies show
that physical work capacity is reduced in this population (1,3,5).
The cause of the low levels of physical work capacity in individuals with MR is not clear. It has been suggested that low levels of
motivation and task understanding influences the ability of persons with MR to perform, limiting their ability to produce true
maximal effort (4). However, recent information suggests this is
not case, and work capacity is reduced in persons with MR
despite valid and reliable maximal efforts (5). Instead it is suggested that physical work capacity may be reduced because of
low levels of physical activity, high incidence of obesity, low levels of leg strength and low maximal heart rates (5,7).
Individuals with Down syndrome (DS) have even lower levels
of physical work capacity than their peers with MR without DS
(2,5,8,14). Although there are many physiological perturbations associated with DS, it is frequently suggested that individuals with DS have low levels of physical work capacity
because of a high incidence of obesity and low levels of physical activity (5,8). However, Fernhall et al, (2) have shown that
a reduction in maximal heart rate is a major contributor to
reduced physical work capacity in individuals with DS. Guerra
et al, (14) recently showed that the low maximal heart rates in
persons with DS are due to chronotropic incompetence which
is physiologically based, probably as a result of altered autonomic function (13).
Obesity lowers physical work capacity in both children and
adults without disabilities (11,15), as well as in children and
adults with MR (1,6). This appears to be the case in individuals both with and without DS (2,6). In addition to lowering
physical work capacity, obesity is associated with lower than
normal maximal heart rates in non-disabled adults (11,12).
Therefore, predicting maximal heart rate is less accurate in
obese individuals, and the reduction in maximal heart rate can
also contribute to the reduced work capacity, because of a
reduction in cardiac output (5). However, it is unknown if obesity is associated with lower than normal maximal heart rates in
children, particularly in children with MR, with or without DS.
It is possible that maximal heart rate would also be lower in
obese children with MR (with or without DS), and thus associated with lower physical work capacity. Since obesity is more
prevalent in children with MR, especially in children with DS,
this may be a larger problem in children with MR compared to
their non-disabled counterparts. However, it is unknown if
obesity alters maximal heart rates in children with MR, with
our without DS. Since obesity is related to autonomic dysfunction (related to low maximal heart rates in non-disabled obese
individuals(10), and adults with DS often exhibit autonomic
dysfunction (13), it is possible that obesity may exacerbate the
reduction in maximal heart rate in youth with DS, further
reducing their work capacity. Because of the large potential
impact of obesity and low maximal heart rate in this population, the purpose of this study was to evaluate the impact of
obesity on maximal heart rate and physical work capacity in
youth MR, both with and without DS.
90
Methods
Subjects
We recruited 89 subjects with DS. Of those, 47 were classified
as obese (OB) and 42 were classified as non-obese (NOB).
Their mean age was 14.5 years, mean height was 147, 5 cm
and mean body weight was 53.9 kg. We also recruited 84 subjects with MR, but without DS, of which 22 were classified as
OB and 62 were classified as NOB. Obesity was classified as a
BMI of 25 or above. The BMI was similar between groups with
(OB=28.9; NOB=20.2) and without DS (OB=28.6;
NOB=19.2). Subjects were recruited from local organizations
and schools, and all subjects lived at home with their parents
or guardians. All subjects were classified with mild MR according to established criteria and all subjects with DS had been
diagnosed with Down syndrome. All subjects were healthy,
none were taking any medication which could affect heart rate
or cardiovascular function, and none of the subjects with DS
had congenital heart disease.
Protocol
Subjects were familiarized with the laboratory and the testing
protocol prior to any data collection. The number of familiarization visits varied depending on the subject. Data collection
commenced when subjects could comfortably walk on the
treadmill with the mouthpiece and nose clip. We employed an
individualized walking protocol, starting at a comfortable walking pace for each subject. Speed was increased until subjects
walked at a fast waling pace, whereafter speed was maintained
constant and grade was increased. During the last 1-2 minutes
of the test, if possible, speed was again increased to bring the
subjects to a jog. Metabolic data were collected using a metabolic cart (calibrated prior to each test) and heart rates were
collected using a heart rate monitor. Tests were stopped when
subjects could no longer keep up with the treadmill speed.
Statistics
Means and standard deviations were calculated for each variable. Group comparisons were made using a 2x2 ANOVA (DS
vs no DS by OB vs NOB). To evaluate the potential impact of
maximal heart rate on aerobic capacity, we used a 2x2 ANCOVA, with maximal heart rate as a covariate. Statistical significance was set at p<.05 for all comparisons.
Results
Age was not different between any of the groups, but BMI was
higher in the OB groups (p<.05). The impact of obesity on
maximal heart rate is shown in figure 1 below. Subjects with
DS exhibited lower maximal heart rates in general and there
was no difference between OB and NOB groups with DS.
Obese subjects with MR without DS exhibited significantly
lower maximal heart rates compared to their NOB peers
(p<.05). Aerobic capacity was lower (p<.05) in the OB groups
and in subjects with DS (figure 2). Controlling for maximal
heart rate equalized aerobic capacity in the group with DS but
not in the group without DS.
Discussion
The main finding of this study was that obese youth with MR,
but without DS, have lower maximal heart rate than normal
weight youth with MR without DS. Conversely, obese youth
with DS exhibited similar maximal heart rate as the normal
weight youth with DS, showing that obesity differentially
revista
19.9.03
0:50
Página 91
affects maximal heart rate in youth with MR with and without
DS. Furthermore, aerobic capacity was higher in normal youth,
regardless of presence or absence of DS, showing that obesity
is associated with lower aerobic capacity in youth with MR.
It is not surprising that obesity lowers aerobic capacity
expressed relative to body weight. This has been shown in
many studies of non-disabled individuals (11,12,15) and it has
also been shown in children and adolescents with MR (1).
Although other methods of normalizing aerobic capacity may
suggest less negative influence of obesity, from a practical perspective, obese individuals still need to move their entire body
weight. Consequently, obesity negatively impacts aerobic
capacity in persons with MR, consistent with data on both children and adults without MR.
Several studies have shown that individuals with MR exhibit
lower maximal heart rates than non-disabled individuals
(1,2,5,7), but most of these studies have been done on adult
populations. Recent data (6) show smaller differences in maximal heart rate between children with MR and their non-disabled
peers. Our current data are in agreement with these findings, as
the normal weight youth with MR (without DS) in this study
exhibited close to normal maximal heart rates. Interestingly, the
obese youth with MR (without DS) exhibited significant reductions in maximal heart rate, consistent in magnitude with other
reports (5). This may suggest that previous studies of individuals with MR may have included many obese subjects, artificially
skewing the data, and providing lower than expected maximal
heart rates. Studies on maximal heart rate in adult, obese nondisabled individuals show maximal heart rates are between 1015 beets lower than expected (11,12), which is similar to the
magnitude of the difference observed compared to expected
maximal heart rates in adults with MR, without DS (5).
Youth with DS exhibited lower maximal heart rate compared to
their peers without DS, consistent with many previous reports
(1,2,5,7,8,9,14). Interestingly, obesity had no impact on maximal heart rate in youth with DS, as the mean heart rate was
almost identical in obese and normal weight subjects. This was
somewhat unexpected, and suggests that obesity impacts the
cardiovascular system differently in persons with DS. Our data
also suggest that DS per se affects maximal heart rate, independent of obesity. It is likely that individuals with DS have
lower than expected maximal heart rates due to autonomic
dysfunction as recently shown by Fernhall and Otterstetter
(13). Consequently, developing strategies to combat autonomic
dysfunction should be an important future consideration in
this population.
References
1.Fernhall B (1997). Mental retardation. In: ACSM, ed. Exercise
Management for Persons with Chronic Disease and Disability.
Champaign, IL: Human Kinetics; 221-226
2.Fernhall B, Pitetti K, Rimmer JH, McCubbin JA, Rinatala P, Millar
AL, Kittredge J, Burkett LN. (1996). Medicine and Science in Sports
and Exercise, 28:366-371
3.Fernhall B (1993). Medicine and Science in Sports and Exercise,
25:442-450
4.Seidl L, Reid G, Montgomery DL (1987). Adapted Physical Activity
Quarterly, 4:106-116
5.Fernhall B, Petitti K (2001). Clinical Exercise Physiology, 3:176-185
6.Pitetti KH, Millar AL, Fernhall B (2000). Adapted Physical
Activity Quarterly, 17:322-332.
7.Fernhall B, McCubbin J, Pitetti K, Rintala P, Rimmer J, Millar AL,
de Silva A (2001). Medicine and Science in Sports and Exercise,
33:1655-1660
8.Guerra M, Roman B, Geronimo C, Violan MA, Cuadrado E,
Fernhall B (2000). Adapted Physical Activity Quarterly, 17:310-321
9.Guerra M, Cuadrado F, Llorens N, Fernhall B (2000). Medicine and
Science in Sports and Exercise, 32:S235
10.Lauer MS, Okin PM, Larson MG, Evans JC, Levy D (1996).
Circulation. 93:1520-1526
11. Hulens, M, G, Vasant, R, Lysens, L, Claessens, E. Muls. (2001).
Scand. J. Med Sci Sports, 11:305-309
12.Miller, WC., Wallace, JP, Eggert, KE (1993). Med Sci Sports
Exerc, 25:1007-1081
13. Fernhall, B., Otterstetter, M (2003). J. Appl. Physiol., 94:21582165
14.Guerra, M., Llorens, N., Fernhall, B (2003). Arch. Phys.Med.
Rehabil. (In Press)
15.Rowland, T (1991). Am. J. Dis. Child. 145:764-768
EFFECTS OF TENNIS-INDUCED MECHANICAL STRAINS
ON MUSCULAR AND BONE TISSUES
Ducher Gaële, Tournaire Nicolas, Prouteau Stéphanie,
Jaffré Christelle, Courteix Daniel
Laboratory of Muscular Exercise Physiology, Faculty of Sport Sciences,
University of Orléans and Inserm ERIT-M0101, Regional Hospital of
Orléans, France
Keywords: bone mineral content, lean tissue mass, young tennis players
Introduction
Large differences in muscular mass and bone mineral content
have been reported between dominant and non dominant arms
in adult tennis players. These differences are attributed to the
mechanical loads encountered by the dominant arm during the
tennis stroke. It is assumed that the genetic, hormonal and
nutritional influences are similar in both arms. Few studies
have investigated the effects of unilateral loading on the arms
of young tennis players (Haapasalo et al., 1998).
The aim of this study was to compare the bone mineral content
and lean tissue mass of both forearms of young tennis players.
Methods
Twenty-six tennis players, aged 11.8±1.6 years, were recruited.
All subjects have been playing tennis at least twice a week.
They started their career at 6.5±2.1 years. Lean tissue mass
(LTM, g) and bone mineral content (BMC, g) of the forearms
and hands were determined by DXA. A Wilcoxon non parametric test was used to compare the measures on the dominant
and non dominant arms. An analysis of covariance was used to
test the influence of LTM on the forearm BMC. The LTM and
BMC side-to-side differences were expressed as percentage
(D%) of the non dominant value. The association between
these two variables was analysed by the Spearman ranked correlation coefficient (rSp).
Results
Significant correlations (p<0.0001) were observed between
LTM and BMC in the dominant (rSp = 0.95) and non-dominant forearms (rSp = 0.90). LTM and BMC were significantly
91
revista
19.9.03
0:50
Página 92
higher in the dominant forearm (p<0.0001). The D% LTM
was 10.4 ± 6.3 % in the dominant arm. Similarly the BMC
values (19.4 ± 18%, p<0.01) were significantly higher in the
dominant arm. When LTM was covaried, this difference was
no longer significant.
Discussion
This study demonstrated greater LTM and BMC values in the
dominant forearm of young tennis players, even though their
training history was relatively short. Results suggest that the
side-to-side difference is influenced to a great extent by the
higher muscular activity and increased bone stress loading
encountered in the dominant extremity during tennis play.
Reference
Haapasalo H., Kannus P., Sievanen H., Pasanen M., Uusi-Rasi K.,
Heinonen A., Oja P. and Vuori I. (1998). J. Bone Miner. Res. 13(2):
310-19
THE EFFECT OF STIMULANT MEDICATION ON
SUBMAXIMAL EXERCISE RESPONSES IN BOYS WITH
ATTENTION DEFICIT/HYPERACTIVITY DISORDER (ADHD)
Mahon Anthony D, Stephens Brooke R
Ball State University, USA
Keywords: stimulant medication, heart rate, VO2
ADHD is characterized by inattentive, hyperactive and impulsive behaviors and is usually treated with stimulant medication. Previous studies have suggested that this type of medication may augment the typical increases in heart rate (HR) and
blood pressure brought on by exercise. However, the effects of
this type of medication on other physiological and perceptual
responses during exercise are not well understood. Thus, this
study was designed to examine the effect of stimulant medication on the physiological and perceptual responses during submaximal exercise in 12 boys (10.9 ± 1.0 yrs) with ADHD.
Each child completed two exercise protocols on a cycle ergometer on separate days. On one day exercise was performed after
the child was treated with his usual morning dose of medication. On the other day exercise was conducted without prior
medication on the day of testing. Exercise was performed at
three intensities (25W, 50W and 75W) for 3 minutes each with
short rest periods interspersed. HR, VO2, the ventilatory
equivalent for VO2 (VE/VO2), respiratory exchange ratio (RER)
and ratings of perceived exertion (RPE) were assessed at each
level of exercise. The data were analyzed with a 2-way (day by
intensity) ANOVA. The day by intensity interaction was not
significant for any of the analyses. A significant main effect
for HR was observed with HR on medication (159.3 bpm)
higher than the HR off medication (149.0 bpm). Treatment
with medication had no effect on VO2, VE/VO2, RER, or RPE.
In addition, pre-exercise medication dose (absolute and relative
to body weight) was not related (r = -0.08 to -0.25; P>0.05) to
the individual differences in HR at each level of exercise
between the two days. In conclusion it appears that the systemic effect of the stimulant medication, used in the treatment
of ADHD, is restricted to the cardiovascular system. However,
92
a medication dose-HR response relationship was not observed.
RPE and other physiological responses during submaximal
exercise in children with ADHD appear to be unaffected by the
use of this type of medication.
EFFECTS OF AN ORAL GLUCOSE CHALLENGE
ON METABOLIC AND HORMONAL RESPONSES
TO EXERCISE IN ACTIVE PREPUBERTAL GIRLS
Foricher Jean-Marc, Boisseau Nathalie, Ville Nathalie,
Berthon Phanélie, Bentué-Ferrer Dominique,
Gratas-Delamarche Arlette, Delamarche Paul
Laboratory of physiology and biomechanic of muscular exercise, France
Keywords: substrate mobilization, challenge in glucose, insulin sensitivity
To examine hormonal and metabolic effects of an oral challenge
in glucose (16 g), fifteen prepubertal girls, age 9-12 yr, were
randomly divided in two groups according to the oral challenge
in glucose.
Each girl performed a 30min ergocycle test at 60% of Wmax.
Among them, 8 ingested an oral glucose challenge between 2
and 3 minutes after the beginning of the exercise whereas the
other 7 girls received no fluid intake. During this test, blood
samples were collected using a venous catheter, in seated position on the bicycle. In the group without oral challenge (Gw)
the measures were made at rest and every 15min. In the group
with oral challenge (Go), the measures were made at rest, at
the 3rd, 5th, 10th, 15th and 30th minute of the test.
Plasma glucose was significantly different according to the oral
challenge at the 15th minute and 30th minute, where Go was
higher than Gw (p<0.001 and p<0.01 respectively). In Go, a
significant increase in plasma glucose concentration appeared
between rest and the 30th minute and between the 15th and
30th minute (p<0.01). Concerning plasma FFA, a problem
occurred, so the statistics between groups were not realised.
Plasma norepinephrine was not influenced significantly by the
challenge in glucose. Concerning plasma epinephrine, a significant difference appeared at the 15th minute (p<0.05) between
Go and Gw, the value obtained in Go was higher than the value
of the Gw group. At last, concerning plasma insulin, no challenge effect was encountered.
In conclusion, the effects of an oral challenge in glucose
ingested after the beginning of an exercise test at 60% of
Wmax in active prepubertal girls confirm previous results well
established in adults. Many studies show that, in adults, plasma glucose can be maintained at steady state when the exercise intensity is not higher than 70-80% of VO2max during one
hour. Indeed, in prepubertal girls plasma glucose is relatively
stable during a 30 minutes exercise test. Besides, the non-significant different values of FFA found in the group Go confirm
the phenomenon of insulino-resistance in prepubertal children
and their capacity to perform prolonged exercise compared to
adults. These results suggest that prepubertal girls receiving
an oral challenge in glucose at the beginning of a prolonged
exercise could longer maintain this exercise, by avoiding a
hypoglycaemia.
revista
19.9.03
0:50
Página 93
EFFECTS OF EXERCISE AND CALCIUM SUPPLEMENTATION ON BONE
HEALTH IN PRE-MENARCHEAL GIRLS: A LONGITUDINAL STUDY
Courteix Daniel, Prouteau Stephanie, Jaffré Christelle,
Lespessailles Eric, Carlson John S.
IPROS Inserm ERIT-M and Laboratoire de la Performance Motrice,
Regional Hospital and University of Orleans, France
Keywords: calcium, exercise, premenarcheal girls
Background
Childhood activity and high calcium intake each improve bone
mass accrual, but their synergistic action has not yet been clarified. This study investigated the combined effects of calcium
supplementation and exercise on bone density and further
examined the residual effects of the intervention on bone
health twelve months following the intervention.
Method
Two milk-powder products containing either 800 mg of calcium
phosphate or placebo were randomly allocated to 113 healthy
premenarchal girls on a daily basis for 1 year. The group was
composed of 63 weight bearing exercise (7.2 ± 4 hours of
exercise/week) and 50 sedentary (1.2 ± 0.8 hours of exercise/week) children. There were 4 experimental groups: exercise/calcium (n=12), exercise/placebo (n=42), sedentary/calcium (n=10), and sedentary/placebo (n=21). Areal bone mineral density (BMD) (6 skeletal sites) and body composition were
determined by DXA. Radiographic measures determined bone
age and the daily spontaneous calcium intake was assessed by
questionnaire. Measurements were taken at baseline, following
the one-year of intervention and 1 year following the cessation
of the treatment.
Results
No differences were observed between groups in bone age, body
height and weight at any stage of the study. At baseline there
was no significant difference in the calcium intake between the
groups. After 1 year of intervention, the total body BMD gains
of the exercise/calcium group (6.3 %, p<0.05) were significantly greater than the gains of all other groups. There was no significant difference between the three other groups. Specific site
significant gains were observed in the exercise/calcium group at
lumbar spine (11 %, p<0.05), femoral neck (8.2 %, p<0.02),
and Ward’s triangle (9.3 %, p<0.01).
One year following the intervention, there were no significant
differences observe in any of the bone accrual measures
between the groups. However, the exercise/calcium group
maintained the significantly higher BMD values at the total
body (p<0.01). The two exercise groups (exercise/calcium and
exercise/placebo) produced greater BMD values than the two
sedentary groups at the femoral neck (p<0.02), Ward’s
(p<0.03), and the subregions of the radius (mid: p<0.02, U
distal: p<0.001, 1/3 distal: p<0.05).
Conclusions
These data reveal that calcium supplementation when combined
with physical exercise produces greater gains in bone health
that just exercise or calcium intake alone. In addition the calcium supplementation without physical activity did not improve
the BMD acquisition in this group of pre-menarcheal girls.
TRAINING IN 10-11 YEAR OLD BOYS: A COMPARISON OF STEADY
STATE AND INTERVAL TRAINING AT TWO DIFFERENT INTENSITIES,
WHILST KEEPING TOTAL WORK CONSTANT
McManus Alison1, Cheng Chi Hong1, Leung Maurice2, Yung TC2
1
Institute of Human Performance, University of Hong Kong, Hong Kong
Division of Paediatric Cardiology, Department of Paediatrics,
University of Hong Kong, Hong Kong
2
Keywords: training, cardiopulmonary, boys
Introduction
Previous studies with young people have indicated that the
magnitude of change in cardiopulmonary function is primarily
dependent on the intensity of the training (Shephard, 1992).
Although there have been attempts to compare the effectiveness of differing intensities using steady state and interval
training protocols (McManus et al., 1997; Williams et al.,
2000), little attempt has been made to keep total work constant. In this experiment we attempted to keep total work constant while comparing steady state cycle ergometer training at
70-75% of maximum heart rate with interval cycle ergometer
training at 85-90% of maximum heart-rate in 10-11 year old
Chinese boys. The study utilized a randomized between-group
design to test the hypothesis that when total work is held constant, the magnitude of change in cardiopulmonary function is
not significantly different between higher intensity interval
training and lower intensity steady state training.
Methods
Thirty-six boys were randomly assigned to one of three groups:
control, steady state or interval training. Both the steady state
and interval groups trained 3 times per week for 8 weeks. The
control group continued with normal physical activity. Similar
total work was confirmed during pilot work, modeling the
interval protocol (interval and rest times) on the total cardiovascular work achieved during a continuous 20-minute cycle
with heart rate 70-75% maximum. Cardiopulmonary function
was assessed pre- and post-training in all three groups from
respiratory gas analysis and heart rate response. Mean differences in submaximal and peak cardiopulmonary responses
were examined using a one-way ANOVA. Differences between
the post-training and pre-training values were compared, with
the pre-training value of each of the variables as the covariate,
and main effects being tested for using the Bonferroni post-hoc
test. Significant differences were accepted at the .05 level.
Results
A significant difference in submaximal heart rate existed. This
was lower in the interval group compared to the control group
[interval: 145(4); steady state: 152(4), control: 160(3)]. At
peak exercise significant differences were found in peakVO2
(l/min) between the control group and interval group, as well
as between the steady state group and interval group [control:
1646(31); steady state: 1736(38), interval: 1867(38)].
Significant differences were also apparent between the control
and interval group in peakVO2 (ml/kg/min), but not however,
between the interval and steady state groups. Similarly the
intensity of exercise at peak was significantly higher in the
interval group (99w) compared to the control group (78w), but
not between the steady state (88w) and interval (99w) groups.
93
revista
19.9.03
0:50
Página 94
Table 1: Descriptive Data
This study has provided evidence that when total work is held
constant, interval training at a high intensity elicits improvement in some cardiopulmonary markers when steady state
training can fail to do so. However, a comparison of the magnitude of change in peakVO2 (ml/kg/min) shows only a small,
non-significant difference exists between the steady state group
(7.5% increase) and the interval group (9.8% increase).
References
Shephard RJ (1992). Sports Med 13:194-213.
McManus AM, Armstrong N, Williams CA (1997). Acta Paediatr
86:456-9.
Williams CA, Armstrong N, Powell J (2000). Br J Sports Med 34:
168-73.
THE VALIDITY OF THE JONES & PEARSON ANTHROPOMETRIC
METHOD TO DETERMINE THIGH VOLUMES IN YOUNG BOYS:
A COMPARISON WITH MAGNETIC RESONANCE IMAGING
Winsley Richard, Armstrong Neil, Welsman Joanne
Children’s Health & Exercise Research Centre, University of Exeter,
Exeter, UK
Keywords: MRI, Lean leg volume, Jones & Pearson
Introduction
Anthropometric techniques of assessing leg muscle volume
have found popularity with child based research due to their
non-invasive nature, ease of use, low cost and fast completion
times (Knapik et al., 1996). The development of Magnetic
Resonance Imaging (MRI) now allows for a more precise, noninvasive determination of muscle volume rather than just lean
tissue volume. However, the high scanning costs and restricted
access to MRI scanners per se has meant that the use of this
equipment in research is limited outside the clinical setting.
The use of anthropometric techniques therefore appears to be
more feasible for child based research, but studies have consistently reported a large differences in measured leg volume
between the two measurement techniques; 7.1-17.7% (Housh
et al., 1994), 22% (Knapik et al., 1996). The Jones & Pearson
(1969) technique in particular has been frequently used in paediatric exercise physiology research, yet there remains the
question of the suitability of this method to accurately predict
the quantity of lean leg tissue in children. Therefore, the pur-
94
pose of this study was to compare the Jones & Pearson anthropometric and Magnetic Resonance Imaging methods in determining thigh volumes in young boys.
Methods
Sixteen boys with a mean (± SD) age of 9.9 ± 0.3y volunteered
to participate in the study. All boys were classified as prepubertal (pubic hair rating 1) (Tanner, 1962). Stature was
measured using a Holtain Stadiometer (Crymych, Dyfed, UK)
to the nearest 1cm. Body mass was measured using an Avery
beam balance (Avery Berkel, Birmingham, UK) to the nearest
0.1kg. Leg volume measures for each child were collected
according to the procedures of Jones & Pearson (1969), using
Holtain skinfold callipers and anthropometric tape measure
(Crymych, Dyfed, UK). The same investigator took all measures at the same time of day for each child. All children
remained inactive prior to measurement. The right leg was
measured in all cases. All children were subsequently taken to
the Somerset MRI centre (Bridgwater, Somerset, UK) to undergo scanning of the thigh region. Scans were performed using a
Philips Gyroscan T5 II (0.5 Tesla). The right thigh was scanned
from medial to lateral in 6mm thick, contiguous, longitudinal
slices. The number of slices ranged from 22 to 27 depending
on the size of thigh. T2 weighted gradient echo images were
produced (20° flip angle, field of view = 450mm, scan matrix =
256 x 256) using a multiple spin-echo sequence (echo time =
20ms, repetition time = 50ms). The region of interest on each
scan was measured from the head of femur to the distal femur
below the medial and lateral condyles. For each scan, total area,
muscle area and bone area were calculated by tracing around
the specific area with a mouse controlled cursor, from which
the computer generated an area measurement using built-in
algorithms. Total slice, bone and muscle volumes were calculated by multiplying the slice areas by slice thickness (6mm).
Total thigh volume, total bone volume and total muscle volumes were calculated by summing all the individual slice volumes. Fat volume was taken to be the residual quantity when
bone and muscle volumes were subtracted from total thigh volume. To enable comparison with the Jones & Pearson (1969)
technique, lean thigh volume was also calculated by summing
muscle and bone volumes for each subject. Statistical analyses
were performed using SPSS computer statistics package
(Version 9) (SPSS Inc., Chicago, Illinois, USA). Paired t-test
analyses were used to determine significant differences between
measurement techniques. Relationships between variables were
investigated through Pearson product moment correlation coefficients. Limits of agreement between the data were calculated
according to the recommendations of Bland & Altman (1986).
Statistical significance was accepted at p≤0.05.
Results
Mean stature and body mass of the boys was 1.40 ± 0.08 (m)
and 31.5±5.2 (kg) respectively. Pearson correlation coefficients between the thigh volume measures calculated by the
two methods were high; r=0.95 (total thigh volume (TTV)),
r=0.79 (lean thigh volume (LTV)) and r=0.90 (fat thigh volume (FTV)), yet there was a significant difference in all mean
values between the two methods (see Table 1). Table 1 indicates that the anthropometric technique under estimates
total, lean and fat thigh volume in young children. This represents an underestimation for TTV of 36%, LTV of 31% and
for FTV 52%.
revista
19.9.03
0:50
Página 95
Table 1: A comparison of lean and fat thigh volume measures calculated by anthropometry and MRI techniques. Values are mean ± SD.
A calculation of the limits of agreement between the two measures (±1.96 SD) (Bland & Altman, 1986) are shown in Table 2.
The figures show that there is a consistent bias towards an
underestimation of actual thigh volume by the Jones & Pearson
(1969) method.
Table 2: Differences and limits of agreement between thigh
volume measures as measured by anthropometry and MRI.
The range of potential underestimation by using the Jones &
Pearson technique represents between 19-52 % for TTV, 1446% for LTV and 5-98% for FTV.
The simplicity and non-invasive nature of using anthropometric techniques to estimate lean or muscle volume has allowed
these techniques to be widely employed in child based
research. However, the specificity of the Jones & Pearson
(1969) technique for use with children has not been previously
questioned. These data indicate that using this particular
anthropometric technique with child subjects greatly underestimates the volume of all leg tissue components. Although the
strong positive correlations between the thigh volumes measured by the two methods suggest that one is a valid predictor
of the other, the significant difference in the measured thigh
volumes raises questions as to the ability of correlation coefficients to indicate agreement between two methods. The limits
of agreement data presented in Table 2 demonstrate that the
size of this underestimation of lean thigh volume ranges from
0.4 – 1.3 L, which represents a significant proportion of a
child’s thigh volume. Scrutiny of the original Jones & Pearson
(1969) paper reveals that the original methods were validated
against water displacement and X-ray methods. The correlation coefficients between the two methods ranged from
r=0.84-0.90, but anthropometry was seen to underestimate the
quantity of adipose tissue even in these original adult subjects.
Indeed it has been reported previously that anthropometry
underestimates cross-sectional areas in comparison to MRI
(Housh et al., 1994; Knapik et al., 1996). Why should anthropometry produce this underestimation? The technique
assumes the limb is a cylinder and that the subcutaneous fat is
evenly distributed. In reality, the leg is not a perfect cylinder
(Knapik et al., 1996; Malina, 1986) and there are individual
differences in fat distribution, which cannot be catered for by
the in-built general regression equations. The MRI method
included sections of the thigh that were omitted from the Jones
& Pearson (1969) method. The region of interest on the MRI
scans was classified as being from the head of femur to the
bottom of the femoral bone. Inevitably part of the gluteal muscles and the adjacent buttock fat were included into the thigh
volume measurement, something omitted using the anthropometric method. The gluteal inclusion does answer the criticism voiced by Winter et al., (1991) who argued that the Jones
& Pearson (1969) method was at fault for not including these
muscles, but this extra tissue may have inflated the MRI measures. Fundamentally, such a difference between the two methods may have arisen because the original Jones & Pearson
(1969) method was validated for use with adults and not children. The regression equations fundamental to the prediction
capabilities of the method are not specific for use with children
and therefore will inevitably produce an error in prediction for
this population. The beauty and simplicity of the method
makes it very attractive for child based research and so it may
be unwise to dismiss the method outright. Indeed, the Jones
& Pearson (1969) method may be used if, as suggested by
Bland & Altman (1986), the appropriate correction factors are
applied (see Table 2).
In conclusion, the Jones & Pearson (1969) method of determining thigh volumes in children greatly underestimates the true
volume. As the use of MRI is both expensive and unfeasible for
many research projects, the Jones & Pearson (1969) method may
be utilised with young children if the appropriate correction factors are included into the estimates of leg volume provided.
References
Bland JM and Altman DG. (1986). The Lancet, February 8th: 307-310.
Housh D et al. (1994). Isokinetics Ex Sci, 4(1): 3-7
Jones PRM and Pearson J. (1969). J Phys, 204: 63-66.
Knapik JJ et al (1996). Med Sci Spts Ex, 28(1): 1523-1530.
Malina RM. (1986). Human growth; a comprehensive treatise.
Tanner JM (1962). Growth at adolescence.
Winter EM et al.(1991). J Spts Sci, 9(1): 3-13
ARE BEDSIDE TECHNIQUES ACCURATE AND SUITABLE
TO ESTIMATE BODY FAT IN ADOLESCENT ATHLETES?
Silva Analiza, Minderico Claudia, Sardinha Luís B
Laboratory of Exercise and Health, Faculty of Human Movement,
Keywords: body composition, athletes, body fat
Introduction
Accurate assessment of body composition (BC) during growth
and maturation is important in many areas of nutrition-related
research including clinical assessment, obesity-related research,
and research into the regulation of growth and development
(Goran, 1996). In addiction, BC assessment in adolescent athletes has an important role when prescribing desirable body
weights, in optimising competitive performance, and in assessing the effects of training 1.
Despite a recent raise of interest in BC techniques, relatively
few studies have specifically addressed methodological aspects
in the paediatric population 2,3. Thus, a small number of specif-
95
revista
19.9.03
0:50
Página 96
ic equations for estimating BC from skinfold-thickness measurements were developed for use in children and adolescents 47. Also, several body fat analysers based on the bioelectrical
impedance analysis (BIA) principles have been widely used in
the clinical setting to estimate percent body fat (%BF) in different populations, including the infancy and the youth period.
Even do it is recognized the need to assess body composition
in paediatric groups, it remains difficult to measure with accuracy and precision, particularly in young athletes.
Although ch anges in fat-free mass (FFM) density have been
described during puberty 8-11, the validity of specific equations
developed for children and adolescents when applied to young
athletes, concerning other potential alterations in FFM density
is not yet clarified. Thus, the validation of those specific models
in other laboratories is needed to assess their generalizability.
Due to chemical immaturity in growing children, multicomponent models should be used as the “gold standard”, against
which other body composition techniques should be evaluated
2. Multi-compartment models such as the three-compartment
(3C), 4C, and the recently 5C molecular model 12, are more
robust to interindividual variability in the composition of FFM.
The 5C molecular model divides body weight into fat, water,
bone mineral, soft tissue mineral, and protein.
Considering the need of accurate data on body composition
assessment during growth and maturation, specifically concerning the athletic population, this study was designed to
assess the performance of the specific skinfold-thickness
equations of Slaughter et al. 4, Deurenberg et al. 6, Sardinha
et al. 7, and two body fat analysers based on BIA principles to
estimate %BF in adolescent athletes, using the 5C molecular
model as the reference 12.
Methods
Sample
A total of 32 girls (age: 15.1 ± 0.3 y; weight: 56.2 ± 14.2 kg;
stature: 1.65 ± 0.13 m; BMI: 20.2 ± 2.6 kg/m2) and 46 boys
(age: 15.3 ± 1.2 y; weight: 71.5 ± 12.3 kg; stature: 1.80 ± 0.12
m; BMI: 22.0 ± 2.5 kg/m2), Caucasian, pubescent and postpubescent, volunteered for the study (Table 1). Subjects were recruited
from several sports clubs and were involved in a variety of sports
(e.g. swimming, basketball, gymnastic, rugby and judo).
According to the regulations of the Ethical Committee of the
Faculty of Human Movement, Technical University of Lisbon,
all subjects were informed about the research design and
signed a consent form. All measurements were obtained with
subjects fasted overnight (≥ 12 h).
Maturation
Subjects were grouped by puberty stage of development, determined by self-assessment according to Tanner 13 stage and
adapted by Ross and Marfell-Jones 14. A self-evaluation
method, with figures, was used to identify the degree of development of the genital organs, breast and pubic pilosity.
Measurements of body composition
Measures of body volume assessed by air displacement plethysmography, bone mineral content by dual-energy x-ray absorptiometry (DXA) and total body water by deuterium dilution
were used to estimate %BF. Briefly, body volume was estimated
using the BOD POD® (Life Measurement Instruments,
Concord, CA) as described elsewhere 15,16. The bone mineral
content was obtained by DXA (QDR-1500; Hologic, Waltham,
96
MA) from the whole body scans and converted to total body
bone mineral (as bone mineral content represents ashed bone)
by multiplying it by 1.0436 17. Total body water (TBW) was
assessed by the deuterium dilution technique using an isotope
ratio mass spectrometer (PDZ, Europa Scientific, UK). After a
completed 12 h fast, an initial urine sample was collected and
immediately administrated a deuterium oxide solution dose
(2H2O) of 0.1g/kg of body weight diluted in 150 mL of water.
After a 4h period new urine sample was collected. Urine was
prepared for 1H/2H analysis using the equilibration technique
of Prosser and Scrimgeour 18. The enrichments of equilibrated
local water standards were calibrated against SMOW (Standard
Mean Ocean Water). Based on delta SMOW, total body water
was estimated by Schoeller and colleagues 19 method, including
a 4% correction due to the recognized amount corresponding
to deuterium dilution in other compartments.
The Wang et al. 12 5C molecular model, was used as the reference method to estimate BF. Accordingly, BF was assessed with
the following equation:
BF (kg)=2.748xBV - 0.715xTBW + 1.129xMo
+ 1.222xMs - 2.051xBM
where BV is body volume (L), TBW is total body water (kg),
Mo is total-body bone mineral (kg), Ms is total-body soft tissue
mineral (kg) and BM is body mass (kg).
To assess %BF from the morphological models, ten skinfolds
were measured, according with Lohman´s 20 procedures, with a
Lange Caliper: abdominal horizontal, abdominal vertical,
biceps, triceps, subscapular, suprailiac anterior, suprailiac medial, mid thigh, and calf. Also, two body fat analysers, BF300 and
Tanita based on BIA principles were used to estimate %BF.
The statistical analyses included examination of the coefficient
of correlation (R), standard error of estimation (SEE), pure
error (PE) and coefficient of variation (CV). Agreement
between models was assessed with the Bland-Altman 21
method. Comparison of means between %BF methods was performed with a Paired t test. A one-sample t-test was used to
assess if the differences were different from zero. Statistical
significance was set as p < 0.05. The statistical analysis was
performed using the Statistical Package for the Social Sciences
(SPSS inc., version 10.0, Chicago, IL) and the MedCalc
Statistical Software (MedCalc Software, Mariakerke, Belgium).
Results
For both genders, table 1 depicts the means and standard deviations values of %BF from the morphological models, BF300,
Tanita and the reference method. Means and standard deviations values are also presented in table 1 for the density and
composition of the FFM, namely water, bone mineral, soft tissue mineral and protein.
revista
19.9.03
0:50
Página 97
Table 1 – Means and standard deviations values of %BF
from the morphological models, BF300, Tanita and the reference
method (%BF5C) for boys and girls. Means and standard deviations
values for the density and composition (water, bone mineral,
soft tissue mineral and protein) of FFM for boys and girls
*Differences between %BF estimated by the 5C model
and the other techniques (p<0.001).
For boys, %BF from the morphological models and the device
BF300 was higher than the reference method (p<0.05), and
was lower than %BF from Sardinha’s model 7. However, %BF
using Tanita did not differ from %BF5C (p>0.05). For girls, all
the morphological models and Tanita presented higher %BF
estimations in relation to the reference method (p<0.05), with
the exception for the device BF300 (p>0.05).
For boys and girls, FFM density is similar to the reference man
(1.100g/cc) but higher than Lohman’s age-adjusted models 22
based on a non-athlete sample of children and adolescent, a
widely used procedure to estimate body fat from 2-component
models during growth and maturation. In addiction, the molecular composition of the FFM, water, bone mineral, soft tissue
mineral, and protein are presented in table 1.
The performance criterias used to validate the above equations
in the present study are shown in table 2.
Table 2 – Performance of predictive equations validated
using the 4C model as reference.
*Significant differences from %BF5C (p<0.001).
Abbreviations: r, correlation coefficient; r2, coefficient of determination; adj, adjusted; SEE, Standard error of estimation; PE, pure error;
CV, coefficient of variation; FM, fat mass; M, male; F, female.
For boys and girls, a reasonable precision was found for the
Slaughter et al. 4, Deurenberg et al. 6 and Sardinha et al. 7 models as presented by the high coefficients of correlation (r) and
lower standard errors of estimation (SEE). When the SEE
value of each equation was standardized for the mean value of
%BF for each equation, the so-called coefficient of variation
(CV) was obtained. This parameter indicates that the lowest is
the CV, the better is the performance of the predictive equation. Considering this fact, morphological models presented a
better performance for girls. Conversely, the pure errors were
higher for both genders, which means that the performance of
these morphological equations when applied in the present
sample of adolescent athletes were poor. The devices, BF300
and Tanita showed a reduced precision as indicated by the
lower r and the higher SEE and CV. And also a poor performance was found for these devices when applied to a sample of
young athletes, as indicated by the PE.
All the models differed from the line of identity, which means
that the slope differed from 1 (p<0.05) and the interception
differed from 0 (p<0.05), with the exception for the
Deurenberg et al. 6 models for both genders (p>0.05) and
Sardinha et al.’s 7 equation and BF300 for girls (p>0.05).
All the equations and BIA devices overestimated %BF as indicated by the bias (p<0.05), with the exception of the Sardinha
et al. 7 equation for boys that underestimated %BF in relation
to the reference method (p<0.05). No bias was found between
the differences of the 5C model with Tanita for girls and with
BF300 for boys (p>0.05).
Agreement between the 5C model and all the bedside techniques were large, particularly for BF300 and Tanita, indicating a
poor performance of these techniques to estimate %BF on an
individual basis. However, the Sardinha et al. 7 equation for boys
presented the smaller limits and no tendency was found between
the difference of the methods and the mean of both methods.
On the other side, a correlation was found in the Slaughter et al.
4 and Deurenberg et al. 6 models for boys and BF300 for girls,
which means that the differences between these techniques and
the reference method were related with body fatness.
During growth and maturation of athletes two sources of variation in the composition of FFM may occur, which are the biological maturity and the changes in body composition due to
exercise. Thus, the biological variability increases the methodological problems in %BF estimation in growing athletes.
Therefore, in the development of new body composition methods a multicomponent model regarding the composition of
FFM is required as reference. For this reason, the 5C molecular
model emerged as the most robust methodological process to
validate bedside techniques. This study revealed that the morphological models and BIA devices were not precise and accurate to estimate %BF in this population.
The poor performance obtained may be explained by the reference method used in the development of the predictive equations, the characteristics of the skinfold caliper and the sample
characteristics. As a result, the models developed by Sardinha et
al. 7 were developed using DXA as reference overestimated %BF
in girls and underestimated %BF in boys. Several studies demonstrated that this method overestimates %BF in relation to the 4C
molecular model 2,23,24, which may explain the obtained overestimation in the predictive equation for girls. However, for boys the
greater body fatness of the male sample used to developed
97
revista
19.9.03
0:50
Página 98
Sardinha et al.’s 7 model may explain the obtained underestimation of the equation when applied in the young athletes.
The results obtained by the Slaughter et al. 4 models presented
a greater adiposity for boys and girls in relation to the 5C
molecular model. Although these models were developed using
a 4C molecular model as reference (body density by underwater weighing, bone mineral by single photon absorptiometry
and total body water by deuterium dilution), the Harpenden
caliper used in the skinfold measurement of the non-athletic
children and youth sample that provided the development of
the Slaughter et al. 4 equations are known to underestimate
skinfold measurements from 1 to 4mm comparing to the Lange
caliper used in the present study 25. The poor performance of
the Deurenberg et al. 6 models in estimating %BF in this sample are related with the reference method used in the development of the Deurenberg et al. 6 equations. These equations
were developed in a non-athletic sample of children and adolescents against a 2C model (body density by underwater
weighing), assuming that density of the FFM slowly increases
with age, from 1.080 g/cc at 7 years 26 to 1.100 g/cc at 18 years
27 in both sexes 5. Concerning that the density of FFM of the
adolescent athletes in the present work was similar to the
adults (1.100 g/cc) the reference method used in the prediction equations of Deurenberg et al. 6 was not appropriate for
the present sample. Furthermore, a Harpenden caliper was
used to measure skinfold thickness in the Deurenberg et al. 6
sample, which is known to underestimate skinfold measurements from 1 to 4mm comparing to the Lange caliper, used in
the present study 25.
The solutions provided by the bioelectrical impedance method
using the devices BF300 and Tanita, were not accurate and
suitable in %BF estimation for this population. Effectively, the
coefficients of correlation were lower and standard errors of
estimation were higher. In addiction, the regression lines
between %BF from the reference method and %BF from BF300
and Tanita differed from the line of identity for both genders.
To estimate FFM and to calculate BF from the difference of
total body mass and FFM, the bioelectrical impedance method
assumes the constancy of FFM hydration. In the manual of
both equipments this value is not refered. However, whichever
the used value, the measurement of the impedance and respective derivation of total body water, FFM and BF, these equipment are inadequate to be used in young athletes.
In conclusion, the morphological models based on skinfoldthickness and the two body fat analysers based on BIA principles were not enough precise and accurate to estimate %BF in
adolescent athletes. Based on a five-component model, these
data illustrate the need for the development of more accurate
models regarding the molecular composition of FFM to estimate body composition in adolescent athletes.
References
1. Sinning, W.E. (1996) Body composition in athletes. In Human
Body Composition (Roche, A.F. et al., eds.), pp. 257-274, Human
Kinetics Publishers
2. Fields, D.A. and Goran, M.I. (2000). J Appl Physiol 89 (2), 613-620
3.Sardinha, L.B. et al. (2003). Acta Diabetol 40(1) (58-63.)
4. Slaughter, M.H. et al. (1988). Hum Biol 60 (5), 709-723.
5.Weststrate, J.A. and Deurenberg, P. (1989). Am J Clin Nutr 50 (5),
1104-1115.
6. Deurenberg, P. et al. (1990). Br J Nutr 63 (2), 293-303.
7. Sardinha, L.B. et al. (2000). Arq Med 14 (2), 68-77
98
8. Boileau, R.A. et al. (1984). Hum Biol 56 (4), 651-666.
9. Lohman, T.G., Boileau, R.A. & Slaughter, M.H. (1984) Body composition in children and youth. Advances in Pediatric Sports and
Sciences. Champaign, I.L:Human Kinetics, 29-57
10. Lohman, T.G. (1986). Exerc Sport Sci Rev 14, 325-357
11. Lohman, T.G. (1992) Advances in body composition assessment,
Human Kinetics Publishers
12. Wang, Z. et al. (2002). Am J Clin Nutr 76 (5), 968-974
13. Tanner, J.M. (1962) Growth and adolescence, Blackwell Scientific
14. Ross, W.D. and Marfell-Jones, M.J. (1991) Kinanthropometry. In
Phsysiological testing of the high-performance athlete (MacDougall,
J.D. et al., eds.), pp. 224-305, Human Kinetics Publishers
15. Dempster, P. and Aitkens, S. (1995). Med Sci Sports Exerc 27
(12), 1692-1697
16. McCrory, M.A. et al. (1995).Med Sci Sports Exerc 27 (12),
1686-1691
17. Heymsfield, S.B. et al. (1990). Am J Clin Nutr 52 (1), 52-58.
18. Prosser, S.J. and Scrimgeour, C.M. (1995). Anal Chem 67
(13(1)), 1992-1997
19. Schoeller, D.A. et al. (1980). Am J Clin Nutr 33, 2686-2693
20. Lohman, T.G. et al., eds (1988) Anthropometric standardization
reference manual, Human Kinetics Publishers
21. Bland, J.M. and Altman, D.G. (1986). Lancet 1 (8476), 307-310.
22. Lohman, T. (1989) Assessment of body composition in children.
Pediatr. Exerc. Sci. 1, 19-30
23. Roemmich, J.N. et al. (1997). J Appl Physiol 83 (3), 927-935
24. Wong, W.W. et al. (2002). Am J Clin Nutr 76 (2), 384-389
25. Pollock, M.L. et al. (1995) The measurement of body composition.
In Physiological assessment of human fitness (Maud, P.J. and Foster,
C., eds.), pp. 167-204, Human Kinetics Publishers
26. Fomom, S.J. et al. (1982). Am J Clin Nutr 35 (5 Suppl), 1169-1175.
27. Siri, W.E., ed. (1961) Body composition from fluid spaces and
density: Analysis of method, National Academy of Sciences
BODY FAT IS MORE RELATED TO BLOOD PRESSURE
THAN BODY MASS INDEX IN ADOLESCENTS
Minderico Claudia, Marques-Vidal Pedro
Superior Institute of Health Sciences South – Lisbon, Portugal
Keywords: hypertension, adolescent, body fat
Introduction
Cardiovascular diseases (CVD) are a leading cause of death in
most industrialized countries including Portugal 1. The development of cardiovascular disease, obesity and other chronic diseases in adulthood is thought to be the result of lifelong
processes having origins in childhood 2. This pathology is the
result of a complex interaction among a variety of risk factors in
which hypertension hypercholesterolaemia and inactivity are
common 3. According to the National Institute of Health 4,
blood pressure values in childhood can predict what they will be
15 years later; this marking is important to evaluate this parameter in children. It is now common to regard obesity in children
as an indicator of future CVD risks during adulthood 5,6. In
adults, the body mass index (BMI) represents a good parameter
to describe overweight and obesity, as it estimates body fat by
simple means7 and predicts cardiovascular risk and mortality 8.
In children it is not known which of the available obesity
revista
19.9.03
0:50
Página 99
parameters can best predict the increased risk for obesity-related diseases and mortality. In the present study was examined
the relationships between body composition parameters, namely, anthropometrics measurements (BMI and waist/hip ratio –
WHR) and percent of body fat (%BF) using the body fat
analyser BF300 based on the bioelectrical impedance analysis
(BIA), with blood pressure levels (systolic and diastolic, SBP
and DBP, respectively) in a sample of adolescents.
Methods
Sample
A transverse study was conducted in a sample of 511 secondary school adolescents (mean age: 16.5 ± 1.1 years) who volunteered for the study.
Measurements
In each child, blood pressure (SBP and DBP), height and
weight, BMI, waist, hip, WHR and %BF were determined.
Body weight was measure by a digital scale (SECA, Hamburg,
Germany) to the nearest 0.1kg, and body height was determined by a stadiometer to the nearest 0.1cm, as indicated by
the standard anthropometrics methods (Council of Europe,
1988). According to the procedures described by Lohman et
al.9, waist circumference was measured to the nearest 0.1cm, at
the smallest circumference of the torso, which is at the level of
natural waist and hip circumference was measured at the level
of maximum extension of the buttocks to the nearest 0.1cm.
The device BF300 (BF300, OMRON Healthcare Europe,
Hoofddorp) based on the bioelectrical impedance analysis
(BIA) was used to assess %BF.
After resting 5 minutes, blood pressure was obtained in the sitting position in the left arm once by an automated device
(OMRON M-4).
The statistical analysis was performed using Spearman correlation and stepwise multivariate regression. Statistical significance was set at p<0.05.
The statistical analysis was assessed using the Statistical
Package for the Social Sciences (SPSS inc., version 10.0,
Chicago, IL).
Results
For boys and girls, means and standard deviations (SD) values
of age, weight, height, BMI, waist, hip, WHR, %BF, SBP, and
DBP, are presented in Table 1.
Table 1 – Means and standard deviations (SD) values of age, weight,
height, BMI waist, hip, WHR, %BF, SBP, and DBP, for boys and girls
For boys, significant correlations were found between SBP and
DBP with: BMI (r=0,31 and r=0,17, respectively, p<0,01),
WHR (r=0,22 and r=0,1, respectively, p<0,01), and %BF
(r=0,26 and r=0,17, respectively, p<0,01). In girls, similar
findings were obtained between SBP and DBP with BMI
(r=0,13 and r=0,30, respectively, p<0,01). However, WHR
presented a significant correlation just with SBP (r=-0,16,
p<0,05), and %BF presented a significant correlation only with
DBP (0,29, p<0,01).
Finally, stepwise multivariate regression analysis adjusting for
age showed that %BF was more related to DBP than BMI or
WHR. In addiction, %BF was also related to SBP in boys,
whereas WHR was related to SBP in girls.
The significant correlations found between BMI and blood
pressure levels in the adolescent males and females support the
results of Boucherd et al. 4,10 that pointed out stature and
weight overload to have an enormous influence on blood pressure values. These data is also in line with the studies conducted by Macedo et al. 1, which revealed that heavier and/or taller
adolescent tend to have higher blood pressure in comparison to
lighter and/or shorter adolescent of the same age, despite the
fact that, stature and weight were analysed as isolated obesityparameters. The significant correlations found between BMI
and blood pressure levels in the adolescent males and females
support the findings of previous studies which have indicated
that in adults and children 11,12 BMI and cardiovascular morbidity and cardiovascular mortality are correlated with each other
8,12-14. Therefore, BMI has been recommended as an appropriate
parameter to define obesity in adults and, more recently, in
children and adolescents 11,12. However, it was also shown that
adolescents obesity defined by the excess of subcutaneous fatness has been associated with elevated BP 15, demonstrating
that high levels of CVD risk factors often accompany excess
body fat in youth. The regression analysis of the present work
showed that %BF was related to blood pressure according with
the findings of Williams et al. 16 which suggested that measurement of both total and regional fatness may be informative
of CVD risk factors, especially for adolescent health screenings.
In conclusion, these results suggest that body fat is more related to BP levels than BMI or WRH in healthy adolescents.
Therefore, body fat might be of interest in the assessment of
adolescents at risk of developing hypertension.
References
1. Macedo, M.E. et al. (1997). Rev Port Cardiol 16 (9), 679-682, 663
2. Berenson, G.S. et al. (1992). Am J Cardiol 70 (9), 851-858
3. Raitakari, O.T. et al. (1997). Med Sci Sports Exerc 29 (8), 10551061
4. NIH. (2000). The Practical Guide Identification, and treatment of
overeight and obesity in adults
5. Clarke, W.R. and Lauer, R.M. (1993). Critical Reviews in Food
Science and Nutrition 33, 423-430
6. Porkka, K.V. et al. (1994). Am J Epidemiol 140 (12), 1096-1110
7. Bray, G.A. (1987). Ann N Y Acad Sci 499, 14-28
8. Calle, E.E. et al. (1999). N Engl J Med 341 (15), 1097-1105
9. Lohman, T.G. et al., eds (1988) Anthropometric standardization
reference manual, Human Kinetics Publishers
10. Bouchard, C. et al. (1993). Endocrine Reviews 14, 72-93
11. Barlow, S.E. and Dietz, W.H. (1998). Pediatrics 102 (3), 1-19
12. Bellizzi, M.C. and Dietz, W.H. (1999). Am J Clin Nutr 70 (1),
99
revista
19.9.03
0:50
Página 100
173S-175S
13. Gunnell, D.J. et al. (1998). Am J Clin Nutr 67 (6), 1111-1118
14. Must, A. et al. (1992). New England Journal of Medicine 327,
1350-1355
15. Gortmaker, S.L. et al. (1987). Am J Dis Child 141 (5), 535-540
16. Williams, D.P. et al. (1992). Am J Public Health 82 (3), 358-363
INCREASED BONE MASS IN THE FINGERS
OF ELITE ADOLESCENT ROCK CLIMBERS
Conclusion
High level rock climbing during adolescence might lead to an
increased bone mass in the fingers by simple muscle contractions without any impact loading. Longitudinal studies have to
be performed, however, to exclude selection bias.
RELATIONSHIPS OF LEPTIN AND ANDROGENS TO BONE MASS
IN PREMENARCHEAL SPORTIVE GIRLS
Jaffré Christelle, Collomp Katia, Courteix Daniel
Kriemler Susi, Schlegel Christian
Laboratoire de la Performance Motrice, Université d’Orléans, France
Dept of Pediatrics, Triemli Hospital, Zurich, Switzerland
Keywords: bone mass, leptin, androgens
Keywords: bone, physical activity, rock climbing
Objectives
Sport activities that are characterized by high magnitudes of
skeletal loading such as weightlifting or tennis have been associated with a higher regional bone density in adolescent athletes. It is not clear however, whether an activity where skeletal
loading is purely through muscle contractions without any compressive forces might also lead to bone mass accumulation. The
purpose of this study was therefore to determine whether high
volume rock climbing was associated with greater than normal
bone mass in the fingers of elite adolescent rock climbers.
Methods
Twenty-nine 10- to 17-year-old nationally ranked rock climbers
took part in the study. Climbing history was assessed by interview, followed by an anterior-posterior radiograph of both
hands. Age-and sex-matched control subjects were selected
from the Zuerich longitudinal study. Cortical thickness of the
second and third proximal (PP) and middle phalanx (MP) of
the 2nd and 3rd finger of the right hand was assessed at the
junction of the distal third and proximal two-thirds (2ndMP-A
and 2ndPP-A, 3rdMP-A and 3rdPP-A) and at the middle of the
phalanx (2ndMP-B and 2ndPP-B, 3rdMP-B and 3rdPP-B). Cortical
thickness was then expressed as percentage of the total width.
Results
Climbers and controls did not differ in age (14.7±1.6 vs.
14.6±2.3 years), height (162.3±25.0 vs. 161.1±14.5 cm) and
weight (52.1±12.1 vs. 49.3±12.3 kg). The climbers were able
to perform a UIAA climbing grade of 8.2±0.56, they trained
5.9±3.3 hours per week during at least a year and they started
their regular climbing career 26.3±16.9 months prior to the
study. Cortical thickness was significantly higher in the
climbers compared to controls at all sites: 2ndMP-A: 37.7±4.7
vs. 33.8±4.7%, p<0.005; 2ndPP-A: 51.7±5.6 vs. 46.9±3.9%,
p<0.0005; 3rdMP-A: 32.4±4.7 vs. 29.5±4.4%, p<0.05; 3rdPP-A:
50.7±4.2 vs. 46.5±2.7%, p<0.0001; 2ndMP-B: 53.6±5.4 vs.
49.1±5.8%, p<0.005; 2ndPP-B: 43.0±4.5 vs. 39.3±5.2%,
p<0.01; 3rdMP-B: 49.0±5.5 vs. 45.4±4.5%, p<0.01; 3rdPP-B:
42.5±3.8 vs. 39.9±4.3%, p<0.05. The relative cortical thickness of all sites but 3rdPP-A correlated significantly with the
duration of the active climbing career (r=0.48-0.56,
0.05>p>0.005).
100
Introduction
In young girls, physical activity increases the bone mass by a
direct effect of the mechanical loading on the skeleton. A
potential effect by way of hormonal activity remains unclear.
Some studies have reported that leptin and androgens concentrations are associated with bone mass in non active women.
The aim of thi study was to analyse the relationship between
serum leptin levels, urinary androgens concentrations and bone
mass in premenarcheal sportive girls.
Methods
Serum leptin and urinary androstenedione and DHEA-S levels
were measured by RIA in 113 premenarcheal girls, includind
63 actives (7.2 ± 4.1 hr/week) and 50 non actives (1.2 ± 0.8
hr/week) subjects. Bone age, Tanner’s stages and anthropometric characteristics were determined in each subject. Bone mineral content (BMC) and density (BMD) were measured by
DXA at the total body and 5 skeletal sites.
Results
Except at the whole body, bone mineral content and bone mineral density were significantly higher in the active as compared
with the non active girls. There were no differences between
the two groups for serum leptin levels and urinary androstenedione and DHEA-S concentrations. A positive correlation has
been found between androstenedione and BMC (r = 0.241 to
0.570, p < 0.05) as well as BMD (r = 0.286 to 0.583, p <
0.05) at all sites in controls. By contrast no relationship was
noticed in sportive girls. In the same way, serum leptin levels
were related with femoral neck and mid radius bone mass (r =
0.210 to 0.487, p < 0.05) as well as density (r = 0.444 to
0.565, p < 0.05) in non active girls. No relationship was found
in active girls.
Conclusion
Our results show a positive relationship between leptin, androgens and bone mass only in non active girls suggesting a role
of these hormones on the bone mass. The lack of relationship
between leptin, androgens and bone mass in active subjects
could suggest that physical activity acts as a modulator of the
hormonal influence.
revista
19.9.03
0:50
Página 101
GENDER DIFFERENCES IN VENTILATORY RESPONSES
OF YOUTH ARE RELATED TO EXERCISE INTENSITY
Murray Robert G1, Baggett Chris2, Pennell Michael3,
Bangdiwala Shrikant3, Harrell Joanne4
1
Department of Exercise & Sport Science, 2 School of Public Health,
University of North Carolina, 3 Department of Biostatistics, 4 School
of Nursing, University of North Carolina, Chapel Hill, NC, USA
Keywords: respiration, ventilatory equivalent, sex
Introduction
The early works of Robinson (1938) have shown that minute
ventilations (VE) during submaximal exercise declines, while
absolute oxygen uptake (L/min) increases, as males aged from
6 to 25 years of age. This results in an improvement in ventilatory efficiency for oxygen (VE/VO2 ratio). In addition, we
know from the work of Rowland and Cunningham (1997) that
at a given VE, tidal volume (VT) increases with a simultaneous
decrease in respiratory frequency (fR) with age. Although these
changes occur, there appears to be little data comparing gender
specific development of these respiratory patterns. In adults,
we know from the research of Aitken et al. (1986) and White
et al. (1983) that gender differences in ventilatory responses
and ventilatory control do exist. However, Rowland and
Cunningham (1997), using 9 girls and 11 boys, ages 8 to 14
years, have suggested that no gender differences exist.
Therefore, the purpose of the present study was to determine
the trajectories of gender differences in the evolution of the
respiratory pattern as it relates to rest and exercise intensity.
Methods
The subjects consisted of 326 youth aged 8 to 18 years who
were participating in the Energy Expenditure of Physical
Activity in Youth Study (EEPAY). They were similarly dispersed
by age and gender such that there were at least nine subject of
each gender per year of age. The data used for this study were
obtained from rest, while walking at 4 and 5.6 km/h, running
at 8 km/h and cycling at 22.4 km/h. Ventilatory measures and
oxygen uptake (VO2) were obtained from breath-by-breath
measurement using a COSMED K2b4 portable metabolic system (COSMED, Rome, IT). The subjects were given time to
become comfortable breathing through the mask. Resting
measurement were taken in a quiet room, with the subject in a
supine position, and a minimum of 3 hours post prandial.
Measurements were taken for 15 minutes, with the first 5-min
and the last minute of measurement eliminated from analyses.
Ventilation and VO2 were obtained during 10-min of walking
and running at each speed. All subjects were habituated to
walking and running on the treadmill. For analyses, the first 2min and final minute was eliminated. If the participant could
not run for a minimum of five minutes, giving us 3 min of
steady state response, there data were excluded. Cycling was
completed using a standard bicycle and a set of training rollers,
simulating cycling on a flat, asphalt road. The children were
not allowed to change the gears. Attainment of steady state
was verified from plots of the data in which there was <1.5
ml/kg/min variation in VO2. The breath-by-breath measures
were averaged over the steady-state time interval to obtain a
mean for each subject for each activity.
Results
There were significant differences in all measures by age
(p<0.01). VO2 (mL/min) increased with age at rest and for all
four activities (p<0.0001). No gender differences for VO2 were
noted at resting, during walking, running (p>0.065), but males
had a higher VO2 during cycling (p=0.046). Minute ventilation
(VE), tidal volume (VT) and PETCO2 increased with age
(p<0.01). There were no significant gender or gender-by-age
interactions for VE at rest or during the four activities
(p>0.088). In addition, VE per kilogram weight declined by
approximately 50% at rest and during exercise as the youth
aged from 8 to 18 years. VT was higher for the older males
than aged-matched females at rest, during walking and running
(p<0.05). PETCO2 was similar between the genders (p>0.11)
and there were no significant age-by-gender interaction
(p<0.26). Respiratory frequency (fR) declined with age
(p<0.0001). There were no significant main effect for gender
but there were gender-by-age interactions for walking and
cycling (p<0.02), with the older females (16-18 y) having a
higher fR than the males. Ventilatory efficiency for oxygen
(VE/VO2) declined with age and was similar between the genders at rest and walking. During the higher intensity exercises
(cycling and running) the VE/VO2 of the females was higher
than males (p<0.004).
Discussion
These data indicated that gender difference in VE were note
evident; however, it is interesting to note that VE for all exercises continued to increase as the males aged until age 17 yrs,
while in the females, VE increased to age 15 then appeared to
level off. Similarly, body mass increased as the males aged,
whereas body mass tended to level off about age 15 years for
the females. Thus growth, or attainment of adult mass,
appears an important determinant of ventilatory responses. In
support, we found a good correlations between VE, height and
weight (R2~0.7). Although there were good correlations
between VE, height and mass, other factors besides these, such
as ventilatory neural drive or mechanical factors, may be
important (Rowland and Cunningham, 1997).
Although VE and VE/kg appeared similar, VE/VO2 ratio, in general, tended to be lower for males than females, in agreement
with Rowland and Cunningham (1997). These differences in
VE/VO2 were not related to changes in body mass or stature, as
the R2 for these relationships were low (R2 = 0.09-0.36). VO2
at rest and during the four activities, although not significantly
different among the genders, did show a trend with the females
being slightly less than the males (p ~ 0.051-0.088). In addition, the VE of the females, in general, was slightly higher than
for the males. The combination of these two small differences,
neither of which in itself are significant, resulted in the
changes in VE/VO2.
Gender differences in VT and fR were evident particularly during late adolescence, and particularly during high intensity
exercise. Aitken et al. (1986) and White et al. (1983) have suggested that in adults, these gender-differences may be related
to differences in the sensitivity to CO2. This may not be the
complete explanation for our youth, as we noted no differences
in CO2 production, as indicated by respiratory exchange ratio,
or PETCO2; however, we did not measure CO2 sensitivity. We
did notice that height was highly correlated to VT and fR, and
that the late adolescent females were generally shorter than the
males. It is possible that the shorter height of the females
101
revista
19.9.03
0:50
Página 102
resulted in a higher stride frequency, which concomitantly
modified neural respiratory drive. This relationship between
stride frequency and respiration rate has been previously
shown in adults (Dejours, 1967; McMurray 1985).
The ability of the younger participants (8-9 y) to increase VT
was quite limited, as VT only increased by approximately 100%
from rest to running (high intensity) exercise. In contrast, the
VT in the late adolescents was approximately 400% from rest
to running. These differences were probably related to the size
of the youth, as the VT/kg was similar during running for 8 and
18 year olds (mean = 20.3 vs. 22.0 ml/kg, respectively) and
not different by gender. The limited ability of the young children to increase VT appears to be compensated by increase fR,
and, consequently, a lower PETCO2 (Cooper et al., 1987).
In adults, the typical ventilatory response to increasing exercise
intensity is for VT to level off at moderate intensities of exercise and further increases during high intensity exercise to
occur by increasing fR. The adult response maximizes ventilatory efficiency (West, 1979). This VT/fR pattern was not evident
in our youth aged less than 15 years. Since the ability to
increase VT was limited in our younger sample, as noted above,
attempts to increase VE must occur via fR. Although this
response is inefficient compared to adults, it allows small children with limited lung capacity to effectively increase VE in
relation to metabolic rate. As our sample aged, and VT
increased more, then changes in VE could be met with less an
increase in fR, increasing the ventilatory efficiency. In support
of our point, our VE/VO2 ratios declined as age increased.
Thus, our results do not totally agree with those of Boule et al.
(1989), who found that in the untrained child (aged 6-15 y),
VT and fR increased in proportion to oxygen uptake.
In conclusion, the data suggests that there are minimal gender
differences in ventilatory pattern during rest and low-intensity
exercise; however, as the intensity of the exercise increases,
gender differences in tidal volume, respiratory frequency and
VE/VO2 become evident. These results also suggest that there
are no gender differences in ventilatory pattern of pre-adolescents and that the development of the adult ventilatory
response to exercise occurs during mid-adolescence, with
males developing a more efficient ventilatory pattern then
females. The difference between children and adults could be
related at differences in CO2 sensitivity, but appear to be more
highly correlated with height and weight of the child.
References
Aitken ML, Franklin JL, Pierson DJ, Schoene RB (1986) J Appl
Physiol 60:1894-1899
Boule M, Gaultier C, Girard F (1989) Respir Physiol 75:225-234
Cooper DM, et al. (1987) Pediatr Res 21:568-572
Dejours P (1967) Circ Res 20:Suppl 1:146-153
McMurray RG, Smith LG (1985) Respira Physiol 62:117-124
Robinson S (1938) Arbeitsphysiol 10:318-323
Rowland TW, Cunningham LN (1997) Chest 111:327-332
West JB (1979) Respiratory Physiology
White DP, et al (1983) J Appl Physiol 54:874-879
EIGHT WEEKS OF HIGH INTENSITY RUNNING INTERVAL-TRAINING
INDUCE AN IMPROVEMENT IN SPIROMETRIC AND MAXIMAL
FLOW-VOLUME VALUES IN HEALTHY PREPUBERTAL CHILDREN
102
Mucci Patrick1, Nourry Cédric1, Baquet Georges2, Deruelle
Fabien2, Guinhouya Comlavi2, Fabre Claudine2, Berthoin Serge2
1
Laboratoire d’Analyse Multidisciplinaire des Pratiques Sportives,
University of Artois, France
2 Laboratoire d’Etudes de la Motricité Humaine, University of Lille II,
France
Keywords: lung, boys and girls, pulmonary capacity
Introduction
Several studies showed that respiratory muscle strength may be
improved by aquatic physical activities in adults. This fact
seems to be involved in the alterations of airway resistance or
maximal expiratory flow-volume in prepubertal girls who have
followed one year of intensive swimming training [1]. However,
swimming need specific breathing pattern during exercise.
Therefore, we questioned if a short training period in running,
as it could be used in school physical activities [2], may induce
an alteration in maximal expiratory flow volumes. The aim of
this investigation was to study the effect of an eight-weeks period of running interval-training in prepubertal children.
Methods
Eighteen prepubertal children (age = 10.0 ± 0.8 yrs, Tanner’s
stade 1) participated to this study. The subjects were divided
into two groups: one Experimental group (n = 9; age = 9.7 ±
0.7 yrs; height = 135.3 ± 8.6 cm; weight = 34.6 ± 12.2 kg)
who followed an high-intensity interval-training programme
associated with school physical education lessons (2
sessions.wk-1 for a period of 8 wk [2]); and one Control group
with untrained children who followed their habitual activities
during the same period (n = 9; age = 10.4 ± 0.5 yrs ; height =
141.9 ± 10.4 cm; height = 40.9 ± 14.2 kg). All the children
performed spirometric and maximal flow-volume tests before
and after the 8-week period. All the children were preliminary
familiarised with the apparatus and the tests. At each investigation time, three maximal flow-volume tests was performed
and the best values were retained as recommended by
American Thoracic Society.
Results
Following the 8-week period, Experimental group showed a
significant increase in forced vital capacity (FVC: +7%), in
forced expiratory volume in l.-s (+11%), in peak expiratory
flow (+17%) and in maximal expiratory flow at 75% of FVC
(+15%) and at 50% of FVC (+18%). None of these changes
was noted in Control group.
revista
19.9.03
0:50
Página 103
Values are means ± SD. ExpG, experimental trained group; CG,
untrained control group; FVC, forced vital capacity; FEV1, forced expiratory volume in 1 s; PEF, peak expiratory flow; MEF75%, maximal
expiratory flow at 75% of FVC; MEF50%, maximal expiratory flow
at 50% of FVC; MEF25%, maximal expiratory flow at 25% of FVC.
Significant difference between pre- and post-training period *P <
0.05, **P < 0.01.
Table 1: Change in spirometric and maximal flow-volume parameters
after eight-week period in trained and untrained groups.
We concluded that the high-intensity interval-training programme during eight weeks seemed to be sufficient to observe
alterations in pulmonary volume and maximal flow-volume
parameters. Improvement in respiratory muscle strength
and/or contractility may be hypothesised [3], nonetheless specific studies on these parameters need to be performed in order
to explain this rapid increase in resting pulmonary function.
Heart rate (HR - beat/min), left ventricular ejection time
(LVET in ms), LVET related to data at rest (LVET rel.), LVET
index (LVETI in ms), duration of cardiac output (LVET⋅ HR in
s), mean systolic ejection rate (MSER in ml/s) were determined. Exercise test in supine reperesented standard work load
and after 4 min. rest submaximal gradually increasing work
load till subjective refusal. The parameters obtained in all subjects under study were computed and statistical analyses were
made using the SAS statistical analysis programme. Statistical
differences were calculated by Student’s criteria, the normal
regression equations relating HR and LVET, expressed in ms
were calculated [Weisler]: LVET = LVETI − b ⋅ HR and used as
a criteria for contractility of myocardium.
Results
During growth and development from 7 to 16 years age related
changes in heart rate and time characteristic of ventricular performance are represented in Table 1. From age 11, gender differences in HR appear as lower values in boys if compared with
girls. At the age of 13, gender differences became signifficant
(P<0.05-0.01). Age related changes in the time characteristic
of ventricular performance were the same for both genders and
manifested in prolonging LVET corresponding to the duration
of the cardiac cycle. The stabilization of LVET rel. was
observed, which constituted, on average, 0.34 of the duration
of the cardiac cycle for females and 0.33 for the males.
References
1. Courteix D et al (1997). Eur J Appl Physiol 76: 264-69
2. Baquet G et al (2002). Int J Sports Med 23: 439-44
3. Farrel P (1981). J Sports Med 21:145-149
AGE RELATED CHANGES IN THE TIME CHARACTERISTIC
OF VENTRICULAR PERFORMANCE
AberbergaAugskalne Liga
Department of Physiology, Riga Stradins University, Riga, Latvia
Keywords: systolic time interval, heart rate, exercise
Introduction
Systolic time intervals (STI) reflect the left ventricle’s hemodynamic environment as well as its contractile status and are
used as criteria of left ventricular contractility [ 3,7,8 ]. In normal individuals ejection time varied inversaly with HR and
directly with stroke volume [ 10 ]. The aim of the present
study was to perform a longitudinal analysis of 1041 observations of the time charasteristic of ventricular performance on a
cohort of females and males between the ages of 7 to 16 years.
Methods
This study represents the analysis of age related changes in the
time characteristic of ventricular performance when more than
100 schoolchildren-volunteers of the same cohort were
observed yearly over a ten-year period. Tetrapolar impedence
cardiography was used measuring systolic volume, ECG and
carotid pulse were recorded at rest and immediately after bicycle exercise. Blood pressure was measured by auscultation.
Table1. Longitudinal data for systolic time intervals
at the ages 7-16. Values are mean ± SD.
High significant correlation took place between the LVET and
HR (r = - 0.61) during the observed period. The relationship
between LVET and HR with increasing age of the subjects
became more pronounced and at the ages 14-16 the slopes
LVET-HR became steeper and LVETI increased. Relatively stable values of LVET⋅ HR for boys and girls corresponded to age
related increase in MSER. In addition, mean values for MSER
varied highly in all age and sex groups (c.v. > 30%).
Regression equations relating HR and LVET are represented in
Table 2.
Average values for LVETI and b during the observed period
were: 342.6± 5.1 and − 1.04± 0.06 for females (n = 536); 351.2
±4.8 and − 1.17± 0.06 for males (n = 482).
103
revista
19.9.03
0:50
Página 104
Table 2. Calculated regression equations
relating HR and LVET, expressed in ms.
Restructuring in the time characteristic of ventricular performance took place due to bicycle exercise of different intensity
(standard and submaximal). Age related tendency to reduce
LVET and relatively stable LVET rel. and LVET⋅ HR were
observed during the standard bicycle exercise. The relationship between LVET and HR became weaker and there were
decreases in LVETI due to exercising. At ages 14-16, when
there existed greately pronounced gender differences in relationship between the LVET and HR, higher values for LVETI
resulted and relationships were more pronounced. Average values for LVETI and b during the whole observed period were:
268.6± 17.5 and − 0.47± 0.14 for females; 270.4± 20.4 and −
0.47± 0.23 for males. The relationship between HR and the last
level of submaximal load of the bicycle exercise with increasing
age became steeper, more pronounced, at ages 14-16 in girls
and 13-16 in boys. With every 50 watt increase boys revealed
lower HR if compared with girls. Restructuring of the cardiac
cycle caused by bicycle exercise of different submaximal intensity revealed shortening of LVET by 15 -30% and LVET rel.
represented 0.50 of the duration of the cardiac cycle. Duration
of the cardiac output prolongated by 30-50% if compared with
data at rest. Revealed decrease in LVET with age did not combine with significant changes in LVET rel. Correlation between
LVET and HR at the last load of increased exercising was
weak, regression coefficient (b) and LVETI decreased during
the observed period. Gender differences revealed higher regression coefficient and LVETI in males if compared with females.
Age related changes during 7 to 16 years revealed a decrease
in HR (r = - 0.46; p<0.01) and gender differences characterised by lower values for boys. Gender differences at the age
of 13 became significant. The time characteristic of ventricular
performance was the same for both girls and boys and manifested in prolonging LVET corresponding to the duration of
the cardiac cycle with age. Statistically no significant differences were found not between STI in girls and boys aged 3-16,
as reported by [ 2 ]. According to our data high significant
correlation took place between the LVET and HR at rest during the whole observed period. This agreed with [ 8 ] considering that HR influenced all of the STI. The relationship
between LVET and HR with increasing age of the subjects
became more pronounced and at the ages 14-16 there was a
steeper rise in LVETI. However they did not reach the level
observed in adults [ 10 ].
104
Figure 1. Relationship between left ventricular ejection time
and heart rate (HR) in boys (LVETb) and girls (LVETg)
as compared with adults (LVETa).
Close correlation between the STI and HR, less striking than in
adults were demonstrated too by [ 9 ]. Our data, based on cardiointervalometry of the same subjects at the ages 15-16 when
magnitude of HR reached that in adults, suggested that changes
in the variables indicated to the incomplete formation of the
endogenic structure of the cardiac rhythmus. However, the
development of the control mechanisms of the mean HR and its
endogenic structure were relatively independent and heterochronic. Beside it, the age related changes in time characteristic of ventricular performance and relatively stable values of
LVET⋅ HR for boys and girls associated with age related increase
in MSER. This gave evidence of strengthening of the pumping
function of heart with age. MSER as a valid indicator of left ventricular function with greater sensivity since calculation corrects
LVET for the size of stroke volume was reported by [ 11 ].
Increase in HR due to exercise was accompaned by shortening
of LVET. LVET varied with enhanced ventricular filling, stroke
volume as well as with HR and myocardial inotropy [ 11 ].
Duration of systole should be affected due to findings [ 6 ] by
an increse in afterload during ventricular relaxation. Our data
in relation to standard exercise revealed age related tendency
to reduce LVET, relatively stable values for LVET rel. and
LVET⋅ HR accompanied by increased MSER and blood pressure. This adaptive response due to observed parameters were
related not only with increasing HR but also with increased
contractility of the myocardium as there was age related
increase in systolic volume. The relationship between LVET
and HR with increasing age became less pronounced and there
was a decrease in LVETI.
During exercise with stepwise increased workloads, mechanical
systole at first decreased lineary with increasing HR, but at
high HR demonstrated a significant curvilinearity with successively smaller decrease of mechanical systole [ 4 ]. In our study
relationship between HR and the last level of submaximal
workload of the bicycle exercise with increasing age became
steeper, more pronounced, at the ages 14-16 in girls and 13-16
in boys. With every 50 watt increase boys revealed lower HR if
compared with girls. Similar findings that girls had higer HR in
submaximal exercise was reported by [ 1, 5 ]. Thus increasing
HR due to intensity of submaximal exercies depended on age
and gender. Restructuring of the cardiac cycle caused by bicycle
exercise of different submaximal intensity revealed shortening
of LVET by 15 -30% and LVET rel. represented 0.50 of the
revista
19.9.03
0:50
Página 105
duration of the cardiac cycle. Duration of the cardiac output
prolongated by 30-50% if compared with data at rest. Revealed
decrease in LVET with age did not combine with significant
changes in LVET rel. Weak correlation between LVET and HR
at the last workload of exercising, lowered regression coefficient (b) and values for LVETI during observed period disagreed with submaximal exercising data for man demonstrated
by [ 4 ] when higher correlation coefficients were present. In
our study gender differences revealed relatively higher regression coefficient and LVETI in males if compared with females
over the observed period.
In conclusion, the gradual increase of duration of the cardiac
cycle with age at rest was followed by the corresponding prolongation of ejection period of left ventricle and a tight relationship between left ventricular ejection time and heart rate
not reaching the level for adults. Adaptive response to bicycle
exercise in supine was characterized with less pronounced
dependence of left ventricular ejection time from heart rate if
compared with adults. The results of the present investigation
suggested that subjects of higher cardiovascular fitness displayed slightly longer ejection times, larger systolic volumes
and faster mean systolic ejection rates at the rest as well as at
the same exercises heart rate.
References
1. Gutin B et al (1997). Children and exercise XIX: 460-4
2. Kasih EN, Hofman W (1984). Klin Padiatr196:360-6
3. Lewis RP et al (1977). Circulation
4. MaherJT et al (1974). Am Heart J 87:334-42
5. Mahon AD et al (2001). Pediatric Exercise Science 13: 319
6. Mobert J et al (1997). Children and exercise XIX: 429-33
7. Solomon SB et al (1999). Am J Physiol277: H 262-7
8. UlmerHE et al (1982). Basic Res Cardiol 77:197-212
9. Vitolo E et al (1991). Acta Cardiol 46:631-40
10. WeisslerAM et al (1961). Am Heart J 62:367-78
11. Wolf LA et al (1978). J Appl Physiol:Respirat Environ Exercise
Physiol 44:55-8
WHOLE BODY PROTEIN TURNOVER IN YOUNG TRAINED
GYMNASTS AS COMPARED TO NON ACTIVE GIRLS
MEASURED WITH [15 N] GLYCINE
Boisseau Nathalie1, Persaud Chandarika2, Jackson Allan2,
Poortmans Jacques R3
1
Laboratoire de la Performance Motrice, UFRAPS de Poitiers,
Poitiers, France
2 Institute of Human Nutrition, University of Southampton,
Southampton, United Kindon
3 Institut Supérieur d’Education Physique et de Kinésithérapie,
Université Libre de Bruxelles, Bruxelles, Belgium
Keywords: children, exercise, protein turnover
Introduction
Nowadays, health professionals encourage children and adolescents to increase physical activity to prevent the emergence of
obesity linked to inactivity in this population. Although the
positive effects of increased physical activity are well known in
adults, most of the physiologic consequences of regular exer-
cise in young subjects are still unexplored. Childhood and adolescence is a time of important growth and development which
induce elevated energy intake and nutrients needs (National
Research Council Food and Nutrition Board 1989). Protein
metabolism play here an important role. It has been shown in
adults that protein oxidation increases with exercise and training (Gontzea et al. 1974, Poortmans 1993, Lemon 1994) and
acute changes in activity may be associated with differences in
protein kinetics in childhood (Bolster et al, 2001), but there is
a lack of information concerning the habitual protein needs in
children and adolescents regularly involved in physical activity.
The purpose of this study is to estimate if regular intensive
physical activity may alter protein turnover in children. To this
end, whole body protein turnover was measured non invasively
in competitive young gymnasts and non active girls of 7-12yr
using the end product method with [15 N] glycine.
Methods
Twenty young girls participated in this study. The subjects were
classified into two groups comprising 10 competitive gymnasts
and 10 non active girls. All the gymnasts had been training
from 5 to 9 h a week for at least 6 months. Ethical approval for
the study was received from the Ethical Committee of the
Université libre de Bruxelles.
Protein turnover: Nitrogen flux (Q), whole body protein synthesis (PS), protein breakdown (PB), and net protein balance
(NB) were determined in young gymnasts and control girls
from a single oral dose of [15N] glycine and collecting total
urine output (Jackson et al. 2000). Enrichment was measured
in urinary ammonia and urea. This method is non invasive and
does not induce any risk for the children.
Protein turnover studies started at night to minimise the effect
of physical activity. The following day, all the subjects were
predominantly non active and food intake were all recorded.
Just before bedtime, children provided a baseline “spot” urine
sample for 15N-ammonia and 15N-urea background and then
emptied their bladders. Then, the procedure required the
ingestion of a single oral dose of 15N-glycine (2mg/kg body; 98
+ atom % enrichment; Cambridge Isotope Laboratories,
Andover, USA) dissolved in orange juice or water. The rate of
nitrogen excretion and the total amount of 15N excreted either
as ammonia or as urea, for a period of 12h. Labelled ammonia
is completely excreted after 12h. For labelled urea, that excreted as 12h is taken as that available for excretion over 12h
although some has been retained within the body pool at 12h
and is only excreted more slowly over the next 12h. For this
reason, and to avoid having to take a sample of blood, the
urine collection was thus performed up to 24h after the initial
dose of tracer. The urine was acidified with 10ml HCL, 6mol/L,
the volume measured and an aliquot was stored at -20°C.
Diets: The habitual dietary intake of each subject was assessed
using a 7 day food record collected by questionnaires and interviews. Nutritional intakes were obtained using a computerised
dietary analysis (Prodiet 5.2, France). Nitrogen balance was
calculated from daily protein intake and urine nitrogen excretion (micro-Kjeldhal method, Fleck et Munro 1965) a week
before the protein turnover protocol.
Calculations: Flux was calculated by the method of Waterlow et
al. 1978 and Fern et al. 1985:
Q = rate of nitrogen excretion x (dose of 15N /
amount of 15N excreted over 12h)
105
revista
19.9.03
0:50
Página 106
Q was determined from urinary ammonia and urea. Results
from both ammonia and urea were averaged.
Rates of protein synthesis and breakdown in the whole body
were derived from the expression:
Q = E + PS = I + PB, where E is the rate of excretion of total
nitrogen in urine, PS is the rate of whole-body protein synthesis, I is the rate of intake from the diet and PB is the rate of
whole-body protein breakdown. All units are expressed as g of
nitrogen/24h. A factor of 6.25 was used to convert g of nitrogen into g of protein. The net protein balance (NB) corresponds to PS-PB.
Statistics: Statistical analysis to compare the control group and
the gymnasts was performed using the Wilcoxon-MannWhitney U-test. All data were presented as means and standard errors of the mean (SEM). P values < 0.05 were considered statistically significant.
Protein turnover (figure 2): Q was 1.13 (± 0.05) and 1.15
(±0.12) g N.kg-1.d-1 in gymnasts and control girls, respectively
(p = NS between the groups). PS was calculated at 6.06 (±
0.27) in gymnasts and 6.53 (± 0.74) g N.kg-1.d-1 in controls. PB
was estimated to 5.45 (± 0.38) and 5.27 (± 0.74) g N.kg-1.d-1 in
gymnasts and in controls, respectively. Despite no statistical
differences for PS and PB between the two groups, the net
protein balance in controls (expressed in g.d-1 , g. d-1 per
kg.BW-1 and kg.FFM.-1) was twice as compared to gymnasts
(p< 0.01).
Fig. 2: Protein metabolism in gymnasts and controls.
*: p <0.01 between both groups.
Results
The morphological data of the two groups are shown in table 1.
Table 1. Morphological characteristics of the subjects.
Values are mean ± SEM.
*: p< 0.01between controls and gymnasts.
Diets: The results showed that most of the nutritional status of
the two groups was similar. The average energy consumption
was insufficient in all subjects to cover the energy expenditure
(±1650 kcal/day). Their diet was near to the recommended
allowances for total carbohydrate intake (53% instead of 55-60%
in the gymnast group) but widely inappropriate for simple sugar
fraction (26% of total energy intake instead of 10% recommended). As well, lipid fraction was too high (35% of total), in addition to inadequate polyunsaturated acid fraction. The protein
distribution was lower in the gymnast group and appeared less
(11.5%) than the recommended value (15%). Insufficient
intakes were registered for several minerals and vitamins (calcium, phosphorus, magnesium, iodine, zinc, vitamins B5, A, E)
and fibres in controls and gymnasts. Both groups showed a positive nitrogen balance with a mean protein intake of 1.39 g.kg1.day-1 in all subjects (1.34 g.kg-1.day-1 and 1.43 g.kg-1.day-1 in
gymnasts and controls respectively, p =NS) (Figure 1).
Fig. 1: Daily nitrogen balance (mg.kg-1.day-1) and protein intake
(g.kg-1.day-1) relationship in gymnasts and controls.
106
Conclusion
Based on 7 day food record questionnaire, the present study indicate that the total daily energy intake and the nutritional status of
the two groups were not appropriate to cover growth, maturation
and exercise needs. Specific recommendations should be
addressed to children, parents and coaches who are aware of the
dietary rules of individuals involved in physical practice.
The amount of food consumed by our subjects indicates a protein need of 1.39 g.kg-1.day-1 in non-active girls and competitive female gymnasts. This result suggests a higher protein
need (± 35%) than the usual Recommended Dietary
Allowances proposal. As already stipulate by Boisseau et al.
(2002) in adolescent soccer players of 15 yr, growth, development and exercise could increase the real protein requirement
in a young well fed population. However, in our study, the
higher protein need does not seem to be strictly related to the
energy expenditure imposed by the exercise training in competitive female gymnasts, rather than a higher need for protein
for metabolism, as shown by similar protein turnover in both
groups. Indeed, whole body protein turnover in young trained
gymnasts as compared to non active girls indicated no significant difference in nitrogen flux, protein synthesis and protein
degradation. The only difference between both groups appears
in the net protein balance which was twice in controls as compared to gymnasts. The lower accretion in gymnasts could be
due to a significant protein oxidation induced by physical activity and/or to a higher nitrogen ingestion in control subjects the
day of the protocol.
The present study postulates that despite their specific training
status, young gymnasts do not need extra protein intake as
compared to non active girls to meet growth, maturation and
exercise needs.
References
Boisseau N, Le Creff c, Loyens M, Poortmans JR (2002). Eur J Appl
Physiol, 88, 288-293.
Bolster DR, Pikosky MA, McCarthy LM, Rodriguez NR (2001). J
revista
19.9.03
0:50
Página 107
nutr 131: 2659-2662.
Fern EB, Garlick PJ, waterlow JC (1985). Clin Sci, 271-282.
Fleck A, Munro HN (1965). Clinica Chimica Acta, 11, 2-12.
Gontzea I, Sutzescu R, Dumitrache S (1974). Nutr Reports Int 10:
35-43.
Jackson AA, Duggleby SL, Grove G (2000). Eur J Clin Nutr 54,
329-336.
Lemon PW (1994). J Sports Sci 12: S17-S22.
National Research Council Food and Nutrition Board (1989)
Commission on Life Sciences Recommended Daily Allowances (RDA),
1Oth ed. National Academy Press, Washingthon, DC.- Poortmans JR
(1993) Protein metabolism. In Principles of Exercise Biochemistry,
Poortmans JR (ed), 2nd, rev ed. Med Sports Sci Basel: Karger, vol 38,
pp 186-229.
Waterlow JC, Golden MHN, Garlick PJ (1978). Am J Physiol, E165E174.
results of these researches allows us to emphasize that an
increase in performance can happen but, generally, is associated
with an improvement in training loads. However, after some
years of training, this increment can’t be kept systematically but
only in determined phases of the year or an athlete’s career.
In present study the greater number of subjects show alterations in 3000 running time lower than 3% (~15s), in agreement with above values of different rankings. This value, even
so relatively low if considered in statistical terms, can be substantial in terms of classification in the ranking performance.
In conclusion we found that: (i) the average values of 3000m
running performance remain stable over six time points; (ii)
there occurred a strong stability of the running performance in
function of time.
PEAK BLOOD LACTATE AND MATURATION IN 11-13 YEAR-OLD
MALE SWIMMERS
STABILITY AND CHANGE OF 3000M RUNNING PERFORMANCE
IN YOUNG WELL TRAINING MALE MIDDLE DISTANCE RUNNERS
Alves Francisco, Noronha Cecília, Vieira Filomena, Fragoso Isabel
Bragada José1, Santos Paulo2, Maia José AR2
Faculty of Human Kinetics, Technical University of Lisbon, Portugal
1
Keywords: lactate, testosterone, swimming
Higher School of Education, Polytechnic Institute of Bragança, Portugal
Porto, Portugal
2
Keywords: performance, distance runners, tracking
The study of changes in performance over time can be made by
identification of the occurred alterations in the average values
and researching aspects of the stability or tracking. Some available research in literature, although appreciating the evolution
of the performance in the 3000m does not appreciate its stability. Therefore the purpose of the present study was to document changes in 3000m running performance in well trained
distance runners throughout two following seasons.
18 Portuguese male well trained distance runners showed at
beginning of the study the following characteristics: over 2
years regular training; 20(3) years old; 64,1(6,2) Kg of body
mass; 175(5) cm of height; VO2max =70,4(9,0) ml/kg/min;
3000m running performance was evaluated in each runner 6
times throughout 2 following years. A multivaried statistical
procedure was used (General Linear Model – repeated measures, SPSS 10,0), for asserting the alterations in function of
time. The index Kappa (k) of Cohen was used for the study of
the tracking (Longitudinal Data Analysis software).
The results indicate that there was no significant change in
mean values of 3000m running performance, during six evaluations accomplished over two following seasons [lambda of
Wilks =0,55; F(5,13)=2,146, p=0,124 ]. This means the
absence of variation of the average values in this period. The
study of the tracking of performance was made by determination of index Choen’s k. The value of k for the group was excellent (k=0,79), i.e., the subjects had strong probability of keeping in the same distribution track along the time. This result is
in agreement with Houmard e col (1991) who found a relative
stability in running performance over time. However, in other
studies there was observed significant changes in middle distance running competitions (Tanaka e col 1984, 1986;
Svedenhag J, Sjodin 1985; Jones 1998). A global analysis of the
Changes in peak blood lactate concentration with age may provide an indication of how children’s glycolityc capacity changes
with growth and development. Metabolic response to exercise
during adolescence are thought to be closely related to the elevated levels of circulating androgen hormones. Eriksson et al.,
(1974) suggested that the evolution of glycolytic capability is
linked to hormonal changes. Recent studies, however, failed to
confirm this hypothesis. The aim of this study was to determine
the influence of maturity on peak blood lactate concentration
and short distance performance in circum-pubertal swimmers.
11 well trained male swimmers participated in this study (Agec:
12.77±0.66 years, height: 156.49±10.549 cm, body mass:
49.72±10.03 kg, %FAT: 20.76±10.50). Each subject performed
3 x 200 m front crawl repeats with 15 min of rest, at a velocity
corresponding to 70%, 80% (v95) and 100% (Vmax) of best
performance in the 200 m freestyle race. The last repeat was
broken in 4 x 50 m with 10” rest to ensure for maximum effort.
Two minutes after the completion of each repeat a blood micro
sample was drawn from the earlobe for lactate concentration
measurement, using the Accusport™ Portable Lactate Analyzer.
Values obtained after the last bout was considered as peak lactate concentration (LaPeak). Serum levels of total testosterone
(Tes) were determined by a immunoanalysis technique (enzyme
linked fluorescent assay, Vidas®/Biomérioux). Skeletal age
(AgeS) based on radiographs of the hand and wrist bones was
assessed acording to Tanner-Whitehouse III Method (TW3).
LacPeak was lower than the usually found in adult swimmers
(10.08±1.46 mmol.l-1) and showed a strong correlation (r =
0.656; p < 0.03) only with Vmax. However Vmax was slightly
related to penis size and very significantly to chronological age.
Tes (1.71±1.61 nmol.l-1), as expected, was well correlated with
AgeS (r = 0.619; p < 0.04) and also with height, arm span and
biacromial breadth. This group of 11 swimmers included 5
late-maturing boys (Tes: 0.98±1.15 nmol.l-1; LaPeak:
9.94±1.58 mmol.l-1) e 2 early-maturing boys (Tes: 3.62±0.92
nmol.l-1; LaPeak: 10.35±0. 64 mmol.l-1), categories defined as,
107
revista
19.9.03
0:50
Página 108
respectively, 1 year behind or ahead AgeS for Agec.
Factors other than maturation during puberty seem to influence peak blood lactate responses, perhaps linked to the
amount of active muscle mass which increases throughout
childhood into adulthood and is strongly activated by chronic
exercise.
USING DATA FROM THE CRITICAL VELOCITY REGRESSION LINE
FOR THE ESTIMATION OF ANAEROBIC CAPACITY
IN INFANT AND ADULT SWIMMERS
Soares Susana, Vilar Sónia, Bernardo Carla, Campos Ana,
Fernandes Ricardo, Vilas-Boas João P
Faculty of Sport Sciences and Physical Education,
Keywords: swimming, aerobic capacity, anaerobic capacity
Introduction
Comparatively with estimations made over the aerobic system,
the evaluation of the anaerobic energetic system, namely in
pre-pubertal athletes, is rather difficult and the results produced are limited (Rowland, 1996). Evaluation of anaerobic
response to the effort of young ages brings us methodological
and, especially, ethical problems. So, controlling the changes
that occur in anaerobic system due to the training is very difficult in any sport. The best measures for the best results are the
ones obtained in real ecological conditions and, most of the
times, its very difficult to work with the evaluation instruments both along the swimming pool or inside the water.
Therefore, easy and non invasive reliable methods are needed
for training evaluation and advice, and are permanently
searched by scientists and coaches.
According to Wakayoshi et al. (1992a,b; 1993) the maximal
velocity that can be sustained without significant participation
of the anaerobic system (critical velocity) and the maximal distance that can be swam using anaerobic system can be determined from the regression line computed between competition
distances and the correspondent swimming times. This regression is defined by an equation type: y = ax + b. The “a” value,
or the slop of the line, or the critical velocity (CV) value, has
been successfully used and is accepted as an indicator of individual swimmers aerobic capacity (Wakayoshy, 1992a, b; VilasBoas et al.,1997; Fernandes and Vilas-Boas, 1998; Rodríguez et
al., 2002). The “b” value, or the y–intercept, has been pointed
out as a possible indicator of swimmers anaerobic capacity
(Jenkins and Quigley, 1991; Hill et al., 1995). Despite some
authors defend that “b” value is not a useful tool for anaerobic
training control (Dekerle et al., 2002) that possibility deserves
to be very well and fully explored, once considered the difficulties in studding swimmer’s anaerobic performance, especially
for the youngest ones.
The purpose of this work was to analyse “b” values in swimming as indicators of individual swimmers anaerobic capacity,
relating: the “b” distance to the correspondent maximal blood
lactate (b[La-]) values and with the b[La-] after a 100 m maximal swimming test (Study one); the “b” value with two anaerobic tests performed on Biokinetic Swim Bench (BSB) - one arm
pull and 45 sec arm pull (study two); the changes in “a” and
108
“b” values with the training process of infant and adult swimmers (study three).
Methods
We performed three studies over a general sample of 39 swimmers of two age groups, infants (10-12 years old) and adults
(15-21 years old), of both genders.
The maturational status of the infant swimmers was determined using Tanner scales for sexual maturation (penis and
breast size) (Tanner, 1962) and all the children were classified
as pre-pubertal.
Study one
For the determination of the individual “b” value, 37 subjects
(12 infant males, 6 infant females, 11 adult males and 8 adult
females) performed two maximal efforts of 50 m and 400 m
front crawl swimming (youngest group) and 50 m and 800 m
(older group). The tests were performed in the same day,
infants in short course and adults in long course swimming
pools. The subjects perform each test starting within water.
The individual distance values used in tests and the correspondent times were plotted in a regression mode.
On day after, rest b[La-]) were firstly determined. After that,
each swimmer performed the “b” predetermined distance using
maximal front crawl swimming. The start jump was cross out
again, and the “b” distance start to be measured only after the
swimmers foot cross over the 5 m swimming pool mark, in
order to have real maximal swimming over the total “b” distance performed. b[La-]) after swimming were collected from
finger tip at 1, 2, 3 and 5 min after effort, for determining maximal value. All the lactate values pre and post efforts were
determined using an automatic analyser Accusport, from
Boehringer Mannheim.
Each swimmer has even performed a single bout of 100 m
front crawl swimming for determination of post effort maximal
b[La-]) value, starting within water. Blood collections were
obtained and analysed as described.
All the tests were performed after a light aerobic warm up and
each swimmer was informed of the importance of swim all the
distances at the maximal velocity.
Study two
females) performed three maximal efforts of 50 m, 100 m and
400 m front crawl swimming (youngest group) and 50 m, 200
m and 800 m (older group). The tests were performed in two
consecutive days (short and long distance in first day and
median distance in second day), in short course swimming
pool. The subjects performed each test starting within water.
The individual distance values used in tests and the correspondent times were plotted in a regression mode. The first test
was performed 10 min after a light aerobic warm up and each
swimmer was informed of the importance of swim all the distances at the maximal velocity. The rest time between the two
tests performed in the first day was of, approximately, 7 min.
After a minimum interval of 48 hours, each swimmer performed, two anaerobic tests on a Biochinetic Swimming Bench
(Sport Fahneman, Germany). The first one consisted on a maximal
45 sec effort performed in simulated front crawl swimming to
determine individual mean power. The second test consisted on
an isolated maximal simultaneous arm pull to determining the
revista
19.9.03
0:50
Página 109
individual peak power. The first test was preceded by a 2 min
warm up at 60% of maximal 100 m front crawl stroke rate. The
level of resistance of the machine was established in level 3 for
infant group and level 4 for adults. The rest time between the
warm up and the first test was of 10 min, and between the two
BSB tests was not inferior to 7 min. All the swimmers were
informed of the necessity of apply the maximal force during the
tests. The results showed on machine digital display have been
video recorded for posterior registration of the data. The start
and the end of the tests were signed by voice. Voice was always
used for motivate the swimmers during the 45 min test.
Study three
females) have performed three maximal efforts of 50 m, 100 m
and 400 m front crawl swimming (youngest group) and 50 m,
200 m and 800 m (older group). The tests were performed in
two consecutive days (short and long distance in first day and
median distance in second day). Test distances were performed
in short course (infant) and long course (adults) swimming
pools. The subjects performed each test starting within water.
The individual distance values used in tests and the correspondent times were plotted in a regression mode. The first test
was performed 10 min after a light aerobic warm up and each
swimmer was informed of the importance of swim all the distances at the maximal velocity. The resting time between the
first day tests was of, approximately, 7 min.
The swimmers were evaluated, as described, in four moments
during the second training macro cycle of the season. The first
evaluation was conducted during the transition period that
occurred between the first and the second macro-cycle (M1).
The second, third and fourth evaluations were made, respectively, after the general preparation period (M2), the specific
preparation period (M3) and the competitive period (M4).
In all three studies chronometric data was obtained using a
manual chronometer.
Statistical procedures were performed on SPSS 11.0 for PC computers and consisted, firstly, on an exploratory analyse of the data
collected. All the variables, in all studies, have a normal distribution. The means and standard deviations were determined. For
means comparisons ANOVA tests were used and Bonferroni pot-hoc
tests were performed. The level of significance was established at
5%. For correlation studies Pearson coefficient (r) was determined.
Results
Study one
The results of this study are presented in table I.
The results show that the mean “b” distances are higher for
infant groups, comparatively with adults. The differences are
significant between infant and adult female groups. The infant
female group is the one who presents the highest registered
mean value.
The most interesting correlation results were found for adult
male and female subgroups between “b” and [La-]b . [La-]netb
seams to reveal a good correlation with “b” distance for adult
and infant male groups.
For studding the results of each age group, independently of
the gender, we correlated the “b” values with [La-]b. The
results showed a very low value for infants (r = 0.29), and a
higher one for adults (r = 0.69). In what concerns the [La]net100, the values obtained for both groups were very lower (r
= 0.28 for the older and r = 0.30 for the youngest ones).
Study two
Table II shows the mean estimated “b” values and the results
of the correlations computed between those values and the two
anaerobic BSB tests performed by the swimmers.
Table II. Mean “b” values and r-values of “b” individual values with performance on one arm pull and 45 sec arm pull tests for each age group.
*Significant for p≤ 0.05.
The mean “b” value of the older swimmers its of the same
magnitude as the one of the infant and there was a higher variability of the adult group values. No significant differences
were found.
The two anaerobic tests performed on BSB are highly and significantly correlated for adults than for infant swimmers.
The infant swimmers show a negative and significant correlation between the “b” distance and the one arm pull anaerobic
test. The same negative relation, but non-significant, as been
observed for the 45 sec test. The adult swimmers have positive
but non-significant correlations, with the same tests.
Study three
Figure 1 show the CV and the “b” variation observed along the
training macro-cycle for each age and gender groups.
Table I. Mean value and standard deviation of “b” distance (“b”) and
r values obtained between “b” distance and b[La-] correspondent to “b”
(r “b” / [La-]b), “b” distance and net b[La-] correspondent to “b” (r
“b” / [La-]netb ), “b” distance and b[La-] correspondent to 100 m (r
“b” / [La-]100), and “b” distance and net b[La-] correspondent to 100
m distance (r “b” / [La-]net100 ), for each group studied.
* Significant for p ≤ 0.05; **Significant for p≤ 0.01.;
***Significantly different from infant males and females.
Fig. 1. CV and “b” changes for each age group and gender
during the studied macro cycle. * significant for p≤ 0.05.
Legend: M1- Moment one; M2 – Moment two;
M3 – Moment three; M4 – Moment four.
109
revista
19.9.03
0:50
Página 110
The results showed very smooth alterations in CV mean values
along the training macro cycle. “b” mean values changed considerably more and tended to be higher for infant group comparatively with adults, exception made for the fourth moment
of evaluation. The variability tend to be higher in adult groups.
Discussion
Study one
Once “b” value could gave us some information about anaerobic
capacity of swimmers it is not strange to expect to find any relation between this “b” distance values and the post exercise
b[La-]. “b” distances have revealed good correlations with [La-]b
and [La-]netb for adult groups, but not for children. This pattern
does not maintained for correlations with b[La-]100 m front
crawl. Such inconsistent results leads us to think that this
method could not be the best one for the determination of
anaerobic capacity, at least for children. Is it admissible that the
possibly higher difficulty of the infants in pacing maximal
swimming rhythms and its lower capacity for accumulate higher
b[La-] after exercise (Rowland, 1996) can explain these results.
It is possible, too, that the distances used for regression were
not the better ones for children. Balonas et al. (2002) and
Soares (2002) have already showed that the “b” distances alter
accordingly to the regression method used. In face of the results
we can hypothesise that the use of “b” as an indicator of anaerobic capacity would be only possible for adult swimmers.
Study two
Just as we stated before, a positive correlation between “b” distance and anaerobic tests performed on BSB would be expected. However, results of this study were very inconsistent too.
The two anaerobic tests performed on BSB revealed a surprisingly negative correlation with “b” distances for infant swimmers. It could be, again, a problem related with the method
used for the determination of “b” in children, since adults
revealed higher correlations between “b” distance and BSB
tests. “b” seams to be, again, nearest of anaerobic potential of
adults. Other factor that could influenced the results is the use
of a BSB test of 45 sec. That may be not so well mastered by
the youngest swimmers.
Study three
The CV results obtained in this study are very consistent and
are in accordance to a similar study conducted by MacLaren
and Coulson (1999), inclusively the non-increments in CV of
older swimmers that could reflect a higher training level. The
low variation of the CV for infant swimmers along to the
fourth moments of the studied macro-cycle is quite unexpected
once it is traditional to emphasise the aerobic training of the
infant swimmers. Contrarily to CV results, “b” distances and
the evolution profile during the macro-cycle were very variable.
Just as has already happen in studies one and two, “b” values
of infant tend to be higher than those of adults, except at the
end of the macro-cycle, when competition takes place. This
results are not similar to those found by MacLaren and
Coulson (1999). This is an interesting result and seams to
show, once again, that the “b” is more sensitive to changes in
adult swimmers, when results are compared with infants.
As general discussion, its interesting to note that the different
distances used in our three studies for regression lines determination produced quite similar “b” values despite previous studies have already showed that the use of different distances in
110
regression influences “b” results (Balonas, 2002; Soares, 2002).
In all the studies the “b” distances tend to be higher in infants,
with the highest values observed in infant females group.
The higher “b” values for infants, specially the ones obtained
for the girls, are strange when we consider the developmental
physiology knowledge. Several authors (for references see
Rowland, 1996) refer the lower anaerobic capacities of the children in comparison with adults and the smaller values of the
females, when compared with male subjects. Our “b” results
are also somewhat different from those of literature. In fact,
the results found in other studies are somewhat inconsistent.
Wilson and Sleivert (1996) have obtained “b” values ranging
from 10 to 25 m for top-level swimmers. Wakayoshi at al.
(1993) in a study with trained swimmers found values ranging
between 17 and 31 m and Vilas-Boas et al. (1997) found a
mean value of “b” of 19,33 m. The most similar values to those
obtained in our studies are the ones published by Hill et al.
(1995). Nevertheless, these authors registered a mean value of
10,2 and 15,7 for young and older swimmers, respectively,
exactly in opposition to our findings on age group differences.
Conclusion
In study one, results pointed out that the “b” distance is correlated with the correspondent b[La-] for the older swimmers. A
very low correlation has been found with the 100 freestyle
b[La-] values for adult and infant swimmers. In study two the
higher correlation result between “b” and BSB tests was found
for adult groups and only for one arm pull test. In study three,
results showed that during the training macro cycle, “b” values
seem to change considerably in opposition with “a” values. The
“b” values have risen at the end of the macro-cycle for the
adult swimmers and were kept stable for infants.
In general, “b” values seem not to provide consistent information’s about the anaerobic performance of swimmers, irrespectively of the age group considered. Although, results of
older swimmers seams to be more coherent than those
obtained for infants.
References
Balonas A et al (2002. Congresso Desporto, actividade física e saúde.
Dekerle J et al (2002). Int. J. Sports Med., 23: 93-98.
Fernandes R, Vilas-Boas JP (1998). Biomechanics and Medicine in
Swimming VIII: 233-238.
Hill DW et al (1995). Paediatric Exercise Science, 7: 281-293.
Jenkins DG, Quigley BM (1991). Ergonomics, 34 (1): 13-22.
MacLaren D, Coulson M (1999). Biomechanics and Medicine in
Swimming VIII: 227-231.
Rodríguez F et al (2002). Biomechanics and Medicine in Swimming.
Rowland TW (1996). Human Kinetics.
Soares S et al (2002). Congresso Desporto, actividade física e saúde..
TannerJM (1962). Blackwell Scientific Publications.
Vilas-Boas JP et al (1997). 9th European Congress on Sports
Medicine.
Wakayoshi K et al (1992a). Eur. J. Appl. Physiol., 64: 153-157.
Wakayoshi K et al (1992b). Int. J. Sports Med., 13: 367-371.
Wakayoshi K et al (1993).Eur. J. Appl. Physiol., 66:90-95.
Wilson B, Sleivert G (1996). New Zealand Swimming Academy High
Performance Centre.
revista
19.9.03
0:50
Página 111
ANAEROBIC PERFORMANCE ON PRE AND POST-PUBERTAL
BASKETBALL PLAYERS
Santos Amândio, Batista RCJ, Fontes Ribeiro CA
Laboratory of Biokinetics, Faculty of Sport Science and Physical
Education, University of Coimbra, Portugal
Keywords: anaerobic, peak power, force velocity test
Documentation about the development of short-term power
output in young people is scarce compared with the abundant
literature describing the development of aerobic power. There
are intrinsic problems with determining peak power from the
Wingate test, particularly with regard to optimal braking force,
which was originally set to optimise mean power. The force
velocity test (FVT) overcomes this problem as several sprints
are completed against different braking forces. By plotting the
highest power achieved for each of these bouts against the
respective braking force the resulting parabola enables peak
power (PPopt) to be calculated accurately for each subject. The
aim of this study was to characterise the anaerobic performance obtained through FVT, vertical jump test and velocity running test in a pre and pos-pubertal basketball players population compared with a control group.
Written informed consent to participate was obtained from 132
boys subdivided in four groups (pre and post-pubertal basketball athletes and control groups). Basketball players ages are:
10.7 ± 0.8 and 17.1 ± 1.0 yrs old; control groups ages are: 10.8
± 0.5 and 17.4 ± 1.0 yrs old. Basketball players body masses
are: 43.06 ± 10.41and 74.28 ± 11.80 kg; control groups masses
are: 37.35 ± 4.58 and 64.94 ± 8.61kg. Basketball players
stature are: 147.59 ± 7.64 and 181.44 ± 8.12 cm; control group
statures are: 142.45 ± 4.22 and 171.84 ± 4.46 cm. The FVT
consisted of 4 to 6 sprints (on a Monark 824E cycle ergometer)
lasting 5 to 8s against a range of randomly presented resistances (75 to 155 g·kg-1). PPopt was determined according to the
procedures described by Winter et al. (1991).
FVT PPopt (in w) squat jump height (in cm) and 10 meter
velocity running (in m/s) were the followings for pre and postpubertal basketball players / control groups. FVT: 333.71 ± 74.91
and 928.88 ± 157.12 W / 315.15 ± 57.95 and 806.26 ± 139.97
W ; squat jump height: 23.3 ± 2.1 and 37.6 ± 4.3 cm / 21.2 ±
2.0 and 31.2 ± 3.1cm; 10 meters velocity running: 4.26 ± 0.45
and 5.19 ± 0.33 m/s / 3.98 ± 0.29 and 5.07 ± 0.27 m/s).
Basketball players are significantly heavier and taller than control groups (pre and post-pubertal). In relation to FVT PPopt,
post-pubertal basketball players are significantly powerful; in
squat vertical jump height basketball players group jump significantly higher (pre and post-pubertal); and in 10 meter
velocity running, only pre-pubertal basketball players are significantly faster.
TIME TO PEAK TORQUE FOR KNEE AND ELBOW EXTENSORS
AND FLEXORS IN CHILDREN, TEENAGERS AND ADULTS
De Ste Croix Mark, Deighan Martine, Armstrong Neil
Keywords: isokinetic, time to peak torque, muscle
The aim of this study was to examine the age and sex associated development in muscle contraction time of the knee and
elbow extensors and flexors using time to peak torque data.
137 subjects participated in this study consisting of three
groups aged 9/10 y, 16/17 y and 21+y. Isokinetic concentric
knee and elbow extension and flexion were measured using a
calibrated Biodex system 3 and time to peak torque determined. ANOVA identified significant (p<0.05) interaction
effects for stature and body mass. A main effect for group for
knee extension (range 0.20-0.26s) and elbow flexion (range
0.33-0.40s) was identified. For elbow flexion the 16/17 y-olds
demonstrated significantly faster time to peak torque than the
9/10 y-olds and adults. No significant interaction or main
effects for knee flexion (range 0.0.19-0.23s) or elbow extension
(range 0.40-0.44s) were observed. Pearson product moment
correlation coefficients identified no significant relationship
between time to peak torque and peak torque for knee and
elbow extensors and knee flexors in all groups. A significant
negative correlation (p<0.05) was found for the elbow flexors
for both 9/10 y-olds and adults for females but not males. To
conclude, no sex differences in contractile speed of the knee
and elbow extensor and flexor muscles were found. Age related
changes in contractile speed appear to be muscle group and
muscle action specific and highlight the insecurity of making
assumptions between muscle groups and actions.
PREDICTION OF SKATING PERFORMANCE WITH OFF-ICE
TESTING IN MALE AND FEMALE ICE HOCKEY PLAYERS
Bracko Michael, Fellingham Gilbert
Institute for Hockey Research, Canada
Keywords: ice hockey, fitness, gender
Introduction
Investigations to find the predictors of skating performance
have been done with males and females separately, in different
studies (Bracko and George, 2001 and Bracko and Fellingham,
1997). No research has examined predictors of skating performance with the sexes combined. This can useful information because at young ages, males and females will play together, or against each other. Bracko and Fellingham (1997) found
that vertical jump height and push-ups predicted acceleration
and speed in young male ice hockey players age 10 - 14 years.
Bracko and George (2001) found 40-yard (36.5-m) dash time
to predict speed in 8 - 16 year old female ice hockey players.
The purpose of this study was to find the off-ice fitness variables that predicted skating performance in male and female
ice hockey players.
Methods
Eighty-three male and female (38 males and 45 females) ice
hockey players were tested. Average age of subjects equals
12.04 years. Regression analysis was used to find the predictors of skating performance. Demographic data included: age
and playing experience. Off-ice fitness was measured with the
following evaluations: body mass, standing height, vertical
111
revista
19.9.03
0:50
Página 112
jump height, maximum push-ups and sit-ups per minute, sit
and reach flexibility, and percent body fat. Skating performance
was measured with the following tests: 6.10-m acceleration,
44.80-m speed, and agility.
aerobic fitness however a significant decline in submaximal lactate levels was observed.
Results
Regression analysis found the following prediction equations to
be significantly (p<.05 for each variable) related to the outcome variables: Acceleration = 2.00565 - 0.00186 x height
(cm) - 0.00361 x vertical jump (cm) (adjusted R-Squared =
0.2232), Speed = 10.44921 - 0.01471 x height (cm) - 0.02180
x vertical jump (cm) (adjusted R-Squared = 0.4950), and
Agility = 16.08844 - 0.02739 x height (cm) - 0.84075 x gender
(males) (females = 1, males = 2) (adjusted R-Squared =
0.4288). These results indicate that a subjects’ standing height,
and vertical jump height, predicted skating acceleration and
speed. Standing height and gender predicted skating agility.
MEASUREMENT OF LOWER LIMB MUSCLE POWER OF
ADOLESCENT BOYS WITH MODERATE INTELLECTUAL DISABILITY
Conclusions
Standing height, and vertical jump height, predicting acceleration and speed indicate taller players, who have a higher vertical
jump, can accelerate faster from a static start and skate faster
over 44.80-m. Standing height and gender predicting agility
indicate taller males have better skating agility. Although no
cause-and-effect can be established, the results suggest vertical
jump may be important when training young male and female
hockey players on the same team. Once predictor variables are
established, training studies can be designed to evaluate the
effect of off-ice training on skating performance. The importance of conducting evaluations that are related to skating is
because professional coaches, general managers, and scouts
consider skating ability a significant factor when selecting players for a team (Hansen and Reed, 1979).
THE INFLUENCE OF A 20 WEEK EXERCISE TRAINING PROGRAMME
ON AEROBIC FITNESS AND SUBMAXIMAL BLOOD LACTATE LEVELS
IN 13-14 YEAR OLD GIRLS
Stoedefalke Kerstin, Armstrong Neil, Welsman Joann
Keywords: exercise training, adolescent girls, blood lactate
This study examined the effect of a 20 week exercise training
programme on aerobic fitness and blood lactate levels in 13-14
year old girls (experimental group =22, control group =19).
Peak oxygen uptake (peak) and submaximal blood lactate levels
were measured at baseline and following the 20 week programme. Training for the experimental group included three
aerobic exercise sessions per week for 20 minutes at an exercise intensity of 75-85% of peak heart rate. Training sessions
were rigorously monitored by all subjects wearing heart rate
monitors throughout each session. The controls were instructed to continue with their daily lifestyle patterns. There were no
significant (p>0.05) differences over time between the groups
for peak. A Significant (p<0.05) decline in submaximal blood
lactate levels was observed in the experimental group after the
20 week programme. These findings suggest that a 20 week
aerobic training period produces no significant changes in peak
112
Chia Michael YH
Physical Education and Sports Science Academic Group, National
Institute of Education, Nanyang Technological University, Singapore
Keywords: muscle power, dual-energy X-ray absorptiometry, moderate
intellectual disability
Introduction
Research has established the reliability and validity of laboratory and field tests for appraising cardiovascular fitness (Fernhall
et al, 1998) and muscular strength (Stadler & Pitetti, 1996) of
young people with mild intellectual disabilities (ID).
Subsequent comparative studies show that young people with
moderate ID have inferior cardiovascular fitness (31) and also
higher levels of body fat than people without ID (Wondra,
2000). Studies of isokinetic muscle strength also show that
young people with moderate ID are significantly weaker than
their peers without ID (Horvat et al, 2000). While there are
research data on the cardiovascular fitness and muscle strength
of young people with moderate ID, there are apparently none
on their capability to perform all-out intensity cycling exercise
such as that which characterizes the WAnT. This paucity of
such data might be due in part, to the lack of an establishment
of a reliable test to assess this sort of exercise in young people
with moderate ID. Additionally, the general perception that
young people with moderate ID might not have the motivation
or the ability to accomplish intense exercise also explain the
lack of research attention in the area (Cormack et al, 2000).
Nonetheless, these views might not be tenable they have not
be confirmed or refuted by research data. Contrarily, it appears
that young people with moderate ID are able to perform
intense exercise since many of them engage in power-type
training and intense exercise when they prepare for competitive events such as those featured in the Special Olympics.
Previous steady-state exercise data show that boys and girls
with moderate ID demonstrate greater variability in their exercise performance than their counterparts without ID (Wondra
et al, 2000). Consequently, the reliability and short-term stability of the exercise measure (e.g. peak oxygen uptake) will be
affected in repeated performances of the same test. However,
the situation as it pertains to all-out intensity exercise or nonsteady state exercise of young people with moderate ID needs
to be examined and elucidated. High intensity exercise data are
insightful as they complement the available steady-state exercise data and provide a more complete picture of the exercising
person with moderate ID. Importantly, assessing the all-out
intensity exercise of participants with moderate ID provides
information about individuals who might be in need of remediation or intervention to address areas of deficiency. Such data
also provide a reference upon which appropriate goals for
improvements can be formulated for boys with moderate ID.
The Wingate Anaerobic Test (WAnT) (Inbar et al, 1996) is by
far the most popular all-out exercise intensity test.
revista
19.9.03
0:50
Página 113
Comprehensive reviews of the test are available (Chia, 2000).
Essentially, the test involves pedalling or arm cranking for 30
seconds at an all-out intensity effort, against a constant applied
force using commonly available cycle ergometers. These
ergometers have be instrumented and customised to be more
sensitive in many laboratories. The outcome variables of interest are PP- a power that is equivalent to two to four times that
which elicits peak oxygen uptake in young people (Blimkie et
al, 1986), and MP, a surrogate measure for local muscle
endurance (Chia, 2000). Despite the WAnT being the test of
choice for populations with various needs, the test has apparently not been used to assess boys with moderate ID. The reasons for this might be that researchers have not considered
that young people with moderate ID are capable of performing
exercise that requires an all-out effort. Therefore the purpose
of the study was to examine the agreement, reliability and variation of PP and MP achieved in the WAnT in adolescent boys
with moderate ID.
Methods
Participants: Participants were 19 male adolescents with ID.
Both participant and parent/guardian informed consents were
obtained prior to testing. The University Institutional Review
Board approved the study. The sampling design was purposive
(Sherill & O’Conner, 1999) in that the participants had to meet
the criteria of moderate ID and come from two MINDS
(Movement For The Intellectual Disabled Of Singapore)
schools in Singapore. Classification of ID was determined
according to the model for diagnosis by Luckasson et al (1992)
and was determined by educational psychologists at the
MINDS schools. Other criteria for inclusion in the study were:
(a) participants were male between the ages of 15 and 17
years; (b) participants were free from any known physical disabilities and chronic disease; (c) participants were not taking
medications affecting heart functions; and (d) participants were
adept at cycling. Boys with Down Syndrome were excluded
from the study since this category of intellectual disability has
its own unique set of physical and mental characteristics.
Anthropometric measurements and determination of sexual maturity
status: Age was computed from the date of birth and date of
examination. Stature, body mass and skinfold thicknesses over
the triceps and sub-scapular regions were measured by techniques described by Weiner and Lourie (1981). A male physician assessed the sexual maturity status of the participants in
accordance to the criteria that are popularised by Tanner
(1962). The method of Tanner involved a visual inspection of
pubic hair development, with a rating of 1-5. A rating of 1 indicated pre-pubertal status and a rating of 5 indicated the attainment of sexual maturity.
Habituation to the test procedures and the test procedures: All participants reported to the laboratory on four different days, over a
two-week period accompanied by two teachers from the
MINDS schools. The WAnT was conducted on a friction loaded
cycle ergometer (Monark 834E; Monark-Crescent AB, Varberg,
Sweden) that was interfaced to a microcomputer. The ergometer was calibrated in accordance to the manufacturer’s instructions immediately prior to the test series and the same
ergometer was used throughout for all tests. The seat height
and handle bars were adjusted appropriately for each participant, and the test resistance was set at 0.74N per kilogramme
of body mass (Chia, 2000).
On the first day, participants practised maintaining a pedal
cadence of 50-60 rpm, over three attempts. Participants were
also taken through the warm-up protocol that was standardized
as four minutes of pedaling at 50-60 rpm against a minimal
applied force (with the load basket supported). This was interspersed with three, all-out intensity sprints of 2-3 seconds
against the test resistance, at the end of the 1st, 2nd and 3rd
minutes. After the warm-up, the participant performed two
minutes of stretching that involved the quadriceps, hamstrings
and groin muscles. The entire practice session took about 40
minutes.On the second day, when the standardised warm-up
was completed, participants performed a15-second WAnT
twice, with a recovery period of 20 minutes separating the two
sprints. The WAnT was initiated from a rolling start (i.e. 50-60
rpm). Throughout the all-out cycle sprint, participants
remained seated and were verbally encouraged to give a maximum effort. Immediately after the test, participants completed
a cool down that involved continuous light pedaling against
minimal resistance and at a self-selected pedal cadence for
three minutes. On the third day, the procedures of the second
day were repeated, except that the test duration was increased
to 30 seconds. On the fourth day, participants completed
another 30-second WAnT, and duplicate fingertip blood samples were taken at two minutes after the WAnT (Chia et al,
1997). The sample was immediately assayed for blood lactate
(BL) concentration using a YSI 2300 Stat Plus whole blood
analyzer (Clandon Scientific, Farnborough, Hampshire, UK).
The analyser self-calibrated with a known concentration of lactate every five samples, and the calibration was checked regularly against commercially prepared standards of verified concentrations. Inertial corrected power data-namely, peak power
(PP), and mean power (MP) that were computed over 1-second
time periods (Chia et al, 1997) over the two 30-second WAnTs
were obtained.Throughout the familiarisation sessions, the
boys’ teachers were present to motivate and encourage to the
participants. Importantly, both the teachers and the researcher
were able to elicit a maximum effort from the participants
when they performed the test. The participants were deemed
to be adequately habituated to the WAnT when the PP
achieved in successive familiarization sessions was not significantly different between repeated WAnT trials.
Statistical analyses: Data were stored and analysed using a SPSS
software programme (SPSS version 10.0). Descriptive statistics-means and standard deviations-for anthropometric variables, PP, MP and BL concentration were generated. Intra-class
reliability coefficients, the 95% limits of agreement, and the
co-efficients of variation for PP and MP, over the third and
fourth test sessions were computed to determine the reliability,
levels of agreement and variation of the variables in the WAnT.
The intra-class reliability co-efficient is a correlation coefficient
that takes into account the relationship between two data sets.
The reliability co-efficient is sensitive to the means of the two
data sets, and also takes into account the actual change in
scores in the data. The 95% limits of agreement provide information about the test-retest differences of the scores in the
two data sets for 95% of the cases. The co-efficient of variation
provides variability information with regard to how the spread
of scores compares with the mean. For all analyses, statistical
significance was established at p<.05.
113
revista
19.9.03
0:50
Página 114
Results
Participant and WAnT performance characteristics
Table 1 presents descriptive anthropometric data, WAnT performance, and blood lactate concentration measured after the
test. In terms of the sexual maturity status of the participants,
86% were Tanner Stage 2 or 3 in their pubic hair development.
The other 14% were adjudged as Tanner Stage 4 in pubic hair
development.
Table1: Descriptive and WAnT performance characteristics of the boys
Data are means and standard deviations.
Reliability and level of agreement of PP and MP for adolescent boys
with moderate ID
Table 2 presents the intra-class reliability co-efficient, indicators of agreement and coefficients of variation for PP and MP
in the WAnT for adolescent boys with ID. The intra-class reliability co-efficients for PP and MP are significant at p<.05.
Table 2: Agreement, reliability and variability
of PP and MP of adolescent boys with moderate ID.
* Significant at p<.05
Discussion
The intellectual disability descriptions of the participants are
consistent with the diagnosis of moderate intellectual impairment (Luckasson et al, 1992). The stature, body mass and sum
of two-site skinfold thicknesses of boys with moderate ID are
in general agreement with their peers without ID for that age
group (Chia, 1998), even though some studies have shown
that the body mass index (BMI) of females with ID were significantly higher than their peers without ID (Wondra, 2000). In
terms of the sexual maturity status, the male adolescents with
moderate ID do not appear to be ahead or delayed in their sexual maturity in comparison to their peers without ID (Chia,
1998). The significance of assessing sexual maturity status as it
relates to anaerobic performance is that there appears to be a
positive maturity effect on WAnT-type performance in some
but not in all studies in normal young people without ID
(Armstrong et al, 2001). Intra-class reliability coefficients were
high for MP and PP at 0.95 and 0.93, respectively. The results
are comparable to those reported for young people without ID
114
(Inbar et al, 1996), and also in physically disabled populations
and in young patients with chronic disease (26), where correlation coefficients for peak and mean power are in excess of 0.90.
It is of interest that test-retest correlation coefficients in
healthy young people in repeated WAnTs are 0.96 for PP and
0.92 for MP (Unithan et al, 1998). By this manner of comparison, it appears that the reliability of all-out intensity exercise
efforts of boys with moderate ID is comparable to that of boys
without ID. Researchers have debated the appropriateness of
the use of inter-class and intra-class correlations, in test-retest
computations to establish reliability (Bland & Altman, 1995) of
the test instrument for various subject populations. The 95%
limits of agreement (4) has been proposed as the more appropriate alternative to establish reliability and agreement
between two data sets, as the method is less affected by sample
heterogeneity, compared to the use of intra-class correlations
(Atkinson & Nevill, 1998). In essence, the 95% limits of agreement represent the test-retest differences for the variables
reported for 95% of the sample cohort tested. However, the
method has yet to take on prominence as few researchers
report on the 95% limits of agreement as an indicator of reliability. Some researchers in sports science have used the 95%
limits of agreement in studies of body composition (Clasey et
al, 1999) and also in studies on the aerobic fitness of adults
with mental retardation (Draheim et al, 1999) but to date,
apparently only Chia (1998) has apparently used it to substantiate the reliability or agreement between data sets of WAnT
performance in young people without ID. Chia (1998), reported that the 95% limits of agreement for a 20s WAnT were (i)57W to 63W for PP and (ii)-40W to 44W for MP, in twentyfive 10 year-old boys without ID. The 95% limits of agreement
for PP (-51W to –5W) and MP (-23W to 16W) in the present
study on boys with moderate ID were well in agreement with
the results reported by Chia (7). In other words, in the case of
MP, when the test is repeated, there is a 95% chance that the
difference between the first MP score and the second MP score
was between –23W and 16W. This is within the range of differences identified by Chia (1998) for boys and girls without ID.
This demonstrated the 95% levels of agreement between
repeated WAnT performances in male adolescent s with ID
were comparable to those of normal young people without ID.
The coefficients of variation for PP and MP (55% and 42%,
respectively) were considerably higher than the 6-7% reported
by Naughton et al (1992) for MP, for six to 12 year old boys
and girls who were skilled at cycling. The present results were
also higher than the 21% to 27% for WAnT power in 10-yearold boys and girls (8). Like their peers without ID, PP was far
less stable as a measure than MP in the participants with ID.
The results demonstrated that boys with ID were more variable
and less consistent in their power performances as a cohort
compared to trained young people and young people without
ID. In the present study, every attempt was made to habituate
the participants to the WAnT and the test environment, and
for the participants to give an all-out effort throughout the 30second test. It is therefore unlikely that the variability of the
WAnT performances was due to a lack of motivation on the
part of the participants since both the participants’ teachers
and the researcher were confident that participants did give an
all-out effort based on their subjective evaluations (facial flushing, accelerated ventilation, and PP in the test was not significantly different from the warm-up and the final familiarisation
session) of the participants’ capabilities. Since PP during the
revista
19.9.03
0:50
Página 115
warm-up phase was not significantly different to that of the
actual test, this was taken as evidence that all the participants
gave a maximum effort during the test. Moreover, all the participants were sufficiently practiced at sprint cycling during the
familiarisation sessions (i.e. no significant difference in PP
between that of the practice trials and during the actual
WAnT). Researchers reported that WAnT performances in populations with disabilities are not only inferior to that of populations of people without ID, they are also more variable (Inbar
et al, 1996). The present result supported this view. Although,
the 95% limits of agreement for repeated WAnT performances
of the adolescent males with moderate ID are in concord with
those reported for young people without ID (e.g. Chia, 1998),
their means for PP and MP of 219W and 155W, respectively
were about 35% and 34% of the PP and MP attained by their
peers without ID, using a similar WAnT protocol (Chia, 1998).
This is in agreement with published norms that were established for healthy untrained male adolescents, albeit using a
dissimilar WAnT protocol (Inbar et al, 1996). The present
results of low peak muscle power (as indicated by PP) and
local muscle endurance (as indicated by MP) were also buttressed by the low post-exercise lactate values taken at two
minutes following the WAnT. Some researchers have used the
post-exercise blood lactate value as an indicator, albeit a blunted one, of the extent of anaerobic metabolism that has taken
place during exercise, and there appears to be a positive correlation between the high power outputs in the WAnT and postexercise lactate concentration (9), however it should be noted
that interpretation of post-exercise BL concentration is fraught
with difficulties because it is a function of not only lactate production in the muscle cell, but also its release into the circulation, its distribution in total body water, and its removal and
uptake by other tissues (Chia, 1998). There are apparently no
data on the post-exercise blood lactate values in people with
moderate ID but the values in the present study are substantially lower than those found for in people without ID of the
same age range (Chia, 1998). The low blood lactate concentration should not be taken to mean that the participants did not
produce a maximum effort since the teachers and researchers
were confident that maximum efforts were elicited (i.e. facial
flushing, heavy breathing and PP in the test was not significantly different to that achieved in the warm-up and familiarization trials). Moreover, the low blood lactate concentrations
after the test could reflect a physiological deficiency in this
group of participants with moderate ID. The present result of
low PP and MP achieved by the boys with moderate ID is consistent with findings in the extant literature where a similar
pattern of low cycle power and power endurance are also documented for children with cerebral palsy (Emons & Baak, 1993)
and children with chronic diseases (Inbar et al, 1996). An
emergent body of information has shown that the steady state
exercise performance of young people with moderate ID is substantially lower to that of young people without ID (Wondra et
al, 2000). The present results suggested that in adolescent boys
with moderate ID, the PP and MP are also poor in comparison
to their peers without ID. The reasons of that are a combination of decreased physical activity and a lack of opportunities
for exercise for people with various forms of disabilities. More
opportunities for exercise and physical activity should therefore
be organised for young people with moderate ID to help them
develop fully their exercise potential. In conclusion, our results
showed that while the reliability coefficients and levels of
agreement between repeated WAnTs are high and comparable
to that of young people without ID, there were greater variations in WAnT power in the adolescent boys with moderate ID
compared to boys without ID.
References
Armstrong, N., Welsman, J. & Chia, M. (2001). Brit. J. Sp. Med.,
35, 118-124.
Atkinson, G. & Nevill, A. (1998). Sp. Med., 26, 222-238.
Bland, J. & Altman, D. (1995).. Int. J. Epidemiol., 24, S7-S14.
Blimkie, C.J., Roche, P. & Bar-Or, O. (1986). Children and Exercise
XII, Rutenfranz, J. (Ed.).
Chia, M.(1998). Ph.D Thesis. University of Exeter. UK.
Chia, M. (2000). Eur. J. Phys. Educ., 5, 231-258.
Chia, M., Armstrong, N. Childs, D. (1997). Pediatr. Exer. Sci., 9,
80-89.
Clasey, J., Kanaley, J., Wideman, L., Heymsfield, S., Teates, C.,
Gutgesell, M., Thorner, M., Hartman, M. & Weltman, A. (1999). J.
Appl. Physiol., 86, 1728-1738.
Cormack, K.F., Brown, A.C., Hastings, R.P. (2000). J. Intel. Dis.
Res., 44, 125-129.
Draheim, C.C., Laurie, N., McCubbin, J.A. Perlins, J.L. (1999). Med.
Sci. Sp. Exerc., 31, 1849-1854.
Emons, H.J.G. Baak, M.A. (1993). Pediatr. Exer. Sci., 5: 412.
Fernhall, B., Pitetti, K.H., Vukovich, M., Stubbs, N.S., Hensen, T.,
Winnik, J. Short, F. (1998). Am. J. Ment. Retard., 102, 602-612.
Horvat, M., Croce, M., Pitetti, K.H. Fernhall, B. (2000). Med. Sci.
Sp. Exer., 31, 1190-1195.
Inbar, O., Bar-Or, O. Skinner, J. (1996). The Wingate Anaerobic Test.
Luckasson, R., Coulter, D., Polloway, E., Deiss, S., Schalock, R.,
Snell, M, Spitalnick, D. Stark, J. (1992). Mental retardation: definition, classification, and systems of supports (9th ed.).
Naughton, G., Carlson, J. Fairweather, I. (1992). Int. J. Sp. Med., 13,
512-51
Sherill, C. O’Conner, J. (1999). APAQ, 16, 1-8.
Stadler, L. Pitetti, K. (1996). Med. Sci. Sp .Exer., 28, S49.
Tanner, J (1962) Growth at Adolescence.
Unnithan, V., Clifford, C. Bar-Or, O. (1998). Sp. Med., 26, 239-251.
Weiner, J.S., Lourie, J.A. (1981). Practical Human Biology.
Wondra, V.C, Pitetti, K.H., Yarmer, D.A. (2000). Med. Sci. Sp .Exer,
32, 1273.
WINGATE ANAEROBIC TEST POWER OF BOYS AND GIRLS
EXPRESSED IN RELATION TO LOWER LIMB MUSCLE MASS AS
DETERMINED USING DUAL ENERGY X-RAY ABSORPTIOMETRY
Chia Michael YH
Physical Education & Sports Science Group, National Institute of
Education, Nanyang Technological University. Singapore
Introduction
Performance in the Wingate Anaerobic Test (WAnT), an allintensity cycle test, is often described in relation to a body size
descriptor (e.g. stature, body mass, fat-free mass), so as to facilitate comparisons between boys and girls, or between distinctive groups (e.g. athletes vs. non-athletes). The use of DEXA
has gained widespread acceptance as a valid and reliable procedure for scientific research in adults and in young people as it is
easy to administer and most established research centers will be
115
revista
19.9.03
0:50
Página 116
able to afford its intermediate cost of operation (Gotfredsen et
al, 1997). Researchers commonly use the ratio method to
address differences in body size but there is a growing conviction that the ratio method may not appropriately normalise
exercise data or produce a size-independent variable that appropriately takes into account differences in body size (Armstrong
& Welsman, 1997; Nevill et al, 1992). Allometric (log-linear)
methods are recommended as more appropriate in accounting
for body size effects as they are able to accommodate data that
are heteroscadastic (Nevill et al, 1992) in nature, that is, as
body size increases (e.g. LLMM), so does the variability of the
performance variable of interest (e.g. PP or MP). In essence, the
technique requires the derivation of a common b exponent for
two different groups by applying the least-squares regression to
logarithmically transformed data (e.g. Ln PP and Ln LLMM)
(Armstrong & Welsman, 1997). Allometric methods have
apparently not been used to describe young people’s power performances in relation to LLMM. Therefore, the aim of the study
was to examine the lower limb muscle power of boys and girls,
as determined in the WAnT that are described in relation to
LLMM using both ratio and allometric methods.
Methods
Participants and assessment of sexual maturity status
Forty-eight boys and thirty-eight girls with the appropriate
written informed consent were involved in the study. Age and
anthropometric variables-body mass and stature, were measured using standard procedures and that used calibrated
machines. All participants had previously completed a familiarization session with sprinting on a cycle ergometer. The session involved three attempts on an abbreviated WAnT protocol.
An experienced female physician assessed the sexual maturity
of the boys and the girls, one participant at a time, in a private
setting, in accordance to the criteria that were popularized by
Tanner (1962). In essence, ratings of pubic hair development
for both sexes were noted and recorded.
LLMM determination using DEXA
The DEXA equipment used was a QDR 4500 Elite X-Ray Bone
Densitometer Hologic model manufactured in Waltham, MA,
USA. The machine was equipped with a patented Hologic continuous calibration system and was operated by a trained and
licenced technician. LLMM was determined using a DEXA procedure that involved the participant, dressed in shorts and a Tshirt, lying still in a supine position on the scanning table with
both feet rotated inward toward each other, and with arms
placed by the side with the palms pronated. LLMM was derived
from the Hologic computer software (Version 9.80).
Data management
The data were stored in computer and analysed using the
Statistics Package for Social Sciences (SPSS for Windows
Version 10.0). Descriptive statistics of the participants-namely,
means and standard deviations for stature, body mass, and
LLMM were generated. Sex differences in descriptive characteristics and WAnT performances (peak power, PP and mean
power, MP) were analysed using one-way analysis of variance
(OW-ANOVA). The best predictor for PP and MP among the
body size descriptors-BM, HT and LLMM was identified using
stepwise linear regression with PP and MP entered respectively
as the dependent variable and BM, HT and LLMM entered as
covariates. Allometric scaling factors for PP and MP for the
boys and girls were identified from log-linear analysis of covariance (ANCOVA), with LLMM entered as the covariate, to
derive a common b exponent for boys and girls (Armstrong &
Welsman, 1997). Power function ratios (i.e. PP/LLMMb and
MP/LLMMb) that are size-independent were subsequently computed (Armstrong & Welsman, 1997; Nevill et al, 1992). The
level of statistical significance was set at p<0.05.
Results
The physical and anthropometric characteristics of the boys
and girls are presented in Table 1.
Table 1: Anthropometric and descriptive characteristics of the participants
* Significantly different at p<0.05. Data are mean ± SD.
Eighty-six percent of the boys and 89% of the girls were
assessed as Tanner stages 3 and 4 for sexual maturity status,
based on the pubic hair criteria. Boys were significantly, taller,
had greater body mass and LLMM than the girls. Stepwise
regression analysis revealed that LLMM was the best predictor
for PP (r=0.78 and r=0.82, p<0.05) and MP (r=0.66 and
r=0.82, p<0.05) in boys and girls.
The relationships between PP and MP and LLMM in boys and
girls are shown in Figures 1 and 2.
Conduct of the WAnT
After a standardized warm-up, participants completed a 30s
WAnT on a cycle ergometer (Monark 834E), from a rolling
start of 60 rev·min-1, with the applied force set at 0.74 N·kg-1
body mass. Inertia-adjusted 1-s peak power (PP) and mean
power over 30s (MP) were computed according to standard
procedures that have been previously described (Chia, 2000;
Chia et al, 1997). In essence, PP was the highest 1-s power
achieved during the test (usually within the first 10s). PP is
often taken as a measure of explosive power (Chia, 2000). MP
was the average power over 30s and is often regarded as a
measure of muscle endurance (Chia, 2000).
Figure 1: PP & LLMM relationship Figure 2: MP & LLMM relationship
116
revista
19.9.03
0:50
Página 117
Log-transformed data analysed by ANCOVA that described the
allometric relationships between WAnT performances (i.e. PP
and MP) and LLMM, revealed common b exponents for PP for
boys and girls as (b=0.65[95% confidence interval=0.47-0.82])
and for MP as (b=0.79 [95% confidence interval 0.49-1.10] for
boys and girls. Despite the boys being taller than the girls, the
inclusion of stature into the log-linear equation(s) did not
make a significant additional contribution to the b exponent.
WAnT performances in absolute terms and described in relation to LLMM are shown in Table 2.
Table 2: Peak and mean power of the participants
in absolute terms and described in relation to LLMM.
* Significantly different at p<0.05. Data are mean ± SD.
Discussion
The DEXA data demonstrated that boys had greater LLMM
than girls, in contrast to previously reported data, that showed
no gender difference in TMV of seven to 15 year old children,
measured using anthropometric methods (Van Praagh et al,
1990). Inter-study participant differences and the limitations of
anthropometric techniques to estimate TMV of the cited study
could account for the dissimilar results between the cited study
and the present study.
A result of the present study showed that boys were significantly taller than the girls and this could explain the greater LLMM
of the boys. Moreover, many studies have shown that after male
puberty, lean muscle mass of boys increases sharply in contrast
to girls of equivalent maturity status (Armstrong & Welsman,
1997; Docherty & Gaul, 1991). However in terms of sexual
maturity, the girls in the present study were slightly more
mature, based on the pubic hair criterion. However, 86% of
boys were assessed as Tanner stages 3 and 4 for sexual maturity.
Peak power (PP) in absolute terms of the boys was 144% that
of the girls. When PP was expressed in ratio to LLMM1.0, PP in
watts per kg LLMM1.0 in boys was still 125% that of girls (see
Table 2). Mean power (MP), in absolute terms and expressed in
ratio to LLMM1.0 were significantly higher in boys than in girls
(see Table 2). This result is not supported by the findings of
others (e.g. Armstrong & Welsman, 1997; Carlson & Naughton,
1994). In essence, results of the cited studies show that during
a period between late childhood and early puberty, girls could
be more powerful, or just as powerful as boys in the WAnT.
This was not apparent in the present study, even though girls
were sexually more mature than the boys. It should be noted
however that in the cited studies of Armstrong & Welsman, and
Carlson & Naughton, PP and MP were expressed in watts and
watts per kg BM1.0, and not LLMM1.0.
Stepwise regression analysis revealed that among the body size
descriptors, BM, HT and LLMM, LLMM was the strongest predictor for PP and MP (see Figures 1 and 2) in boys and girls.
This was expected since LLMM was more specifically engaged
than BM or HT in the generation of PP and MP in the WAnT.
This result suggested that BM or HT should not always be the
body size descriptor of choice when expressing performance in
relation to body size. Rather, the body size descriptor of choice
should be based on the informed decision of the researcher, and
where possible the decision should be buttressed by the results
of statistical analysis, as was the case in the present study.
Although the use of allometric modeling of data is common in
biological science (Schmidt-Nielsen, 1984) its use in sports science is less widespread (Armstrong & Welsman, 1997; Chia,
1998). The use of the common ratio method among sports scientists to compare performances (e.g. PP in W/kg BM1.0 or peak
V02 in ml/min/kg BM1.0) between distinct groups (e.g. male vs.
female, athletes vs. non-athletes), without first verifying if the
common b exponent is equal or not significantly different from
1.0 has been criticized as inappropriate (Armstrong &
Welsman, 1997). Such indiscriminate use of the ratio method
without proper verification of its suitability of application to
data sets could potentially lead to erroneous interpretations.
Power function ratios derived for PP (W/kg LLMM0.65) and MP
(W/kg LLMM0.79) for boys and girls revealed that boys were significantly more powerful than girls (see Table 2). This result
contrasted with the result of no sex difference in allometrically
adjusted peak oxygen uptake expressed in relation to TMV in
13 to 14-year-old boys and girls (Armstrong & Welsman, 1997).
However, the finding that boys were more powerful than girls
in maximal exercise tests is supported by other studies
(Docherty & Gaul, 1991). Even though testosterone was not
measured in the present study, many researchers are of the
view that boys are more powerful than girls after puberty
because of increased musculature and the effects of circulating
testosterone in boys (Docherty & Gaul, 1991; Van Praagh et al,
1990). However, it should be noted that in the cited studies,
the performance comparisons have been made using PP and
MP expressed in ratio to BM1.0 or to HT1.0.
In the present study, b exponents identified for PP (i.e. b=0.65,
p<0.05) and MP (i.e. b=0.79, p<0.05) in boys and girls, in
relation to LLMM were markedly different from 1.0, which is
the b exponent used in the simple ratio method. These results
of the present study echoed the arguments of others (e.g.
Armstrong and Welsman, 1997; Nevill et al, 1992) that the
simple ratio method inappropriately adjusts for body size differences in groups.
It is noted that the b exponents identified for PP and MP that
were expressed in allometric terms in relation to LLMM, were
close to b=0.67 as predicted by geometric similarity theory
(Schmidt-Nielsen, 1984). However, it should be cautioned that
the exponent b=0.67 should not, like the b exponent used in
the simple ratio method (i.e. b=1.0) be applied indiscriminately to all data sets. It is prudent to derive the exact b exponent
to appropriately describe the relationship between a performance variable and the body size descriptor so as to accurately
generate a size-free variable in the form of a power function
ratio (i.e. performace/body size descriptorb exponent)
Conclusion
Data in the study support that there are sex differences in PP
and MP generated by 13-14 year old boys and girls when the
performances were allometrically adjusted for in relation to
LLMM. Despite a similar interpretation of boys generating significantly greater WAnT power than girls when the same dataset was ratio-scaled to LLMM1.0, in order to appropriately
adjust for the influence of body size, the identified b exponent
117
revista
19.9.03
0:50
Página 118
should be used rather than a b exponent of 1.0.
Common b exponents, for boys and girls that defined the allometric relationship between PP and MP in the WAnT were not
exactly 1.0 (i.e. b exponent used in the ratio standard), but
were close to 0.67 as suggested by geometric similarity theory.
It is therefore strongly recommended that sample-specific allometric modeling of the data be used to appropriately describe
relationships between power elicited in the WAnT and the relevant body size descriptor, in this case LLMM.
References
Armstrong, N., Welsman, J. (1997). Young People and Physical
Activity.
Carlson, J. Naughton, G. (1994). J Sp Med Phy Fit, 34: 362-369
Chia, M. (1998). Ph.D thesis. University of Exeter. UK
Chia, M. (2000). Eur J Phy Educ, 5 (2): 231-258
Chia, M., Armstrong, N., Childs, D. (1997). Pediatr Exerc Sci, 9: 80-89
Docherty, D., Gaul, C.A. (1991). Int J Sp Med, 12: 525-532
Gotfredsen, A., Baeksgaard, L., Hilsted, J. (1997).. J Appl Physiol,
82: 1200-1209
Nevill, A., Ramsbottom, R., Williams, C. (1992). Eur J App Physiol,
65: 110-117
Schmidt-Nielsen, K. (1984). Scaling: Why is animal size so important?
Tanner, J.M. (1962). Growth at Adolescence.
Van Praagh, E., Fellman, N., Bedu, M., Falgairette, G., Coudert, J.
(1990). Pediatric Exercise Science, 2: 336-348
118
revista
19.9.03
0:50
Página 119
PHYSICAL ACTIVITY, SCHOOL ENVIRONMENT
AND MOTOR PERFORMANCE
revista
19.9.03
0:50
Página 120
revista
19.9.03
0:50
Página 121
GENDER DIFFERENCES IN LONGITUDINAL CHANGES OF MAXIMAL
SHORT-TERM LEG PEAK POWER DURING GROWTH
Martin Ronan1, Doré Eric1, Twisk Jos2, Van-Praagh Emmanuel1,
Bedu Mario1
1
Laboratory of Exercise Physiology, Auvergne University, ClermontFerrand, France
2 EMGO Institute, Faculty of Medicine, Free University, Amsterdam,
The Netherlands
Keywords: multilevel regression analysis, qualitative muscular factors,
cycling
Introduction
Although it provides the only method for the direct study of
the natural course of human growth and development, longitudinal data on young people’s short term power output (Pmax)
are sparse. Recently, using an apropriate statistical method for
multiple longitudinal data analysis (multilevel regression analysis; MlwiN) Armstrong et al. (2001) demonstrated that Pmax
values are higher in boys than in girls and that gender differences increase with age. It may be attributable to quantitative
(muscle volume) and qualitative (muscle fiber type, anaerobic
energy production and neural adaptation) muscular factors.
However, Pmax was not standardized to the effective muscle
quantity and younger age groups are missing. Moreover, the
authors don’t use the optimal pedalling frequency (Vopt; rpm)
and force (Fopt; N) as done by Martin et al. (2003) with the
force-velocity test. The purpose of the present multiple longitudinal study is to examine the effect of lean leg volume (LLV),
body mass and age on Pmax in both sexes from 7.5 to 17.5
years using multilevel regression analysis with multiplicative
allometric equations. Additionally, the measurement of Vopt
and Fopt with the force-velocity test will provide information to
understand gender differences better.
Methods
Subjects consisted of 100 girls and 109 boys divided in eleven
cohorts which cover the human growth pubertal period from
7.5 to 17.5 years old. Individual were measured twice and the
time interval between the two measurements was 3.8±0.4 years.
Each session period was used for anthropometric measurement
including LLV, mass and leg length (LL) and for a short term
cycling power test (Doré et al., 2000). Pmax was defined as the
apex of the power-velocity relationship. Fopt and Vopt corresponded to the force and pedalling frequency at Pmax.
Results
Figure 1 showed that the increase of Pmax doesn’t depend on
sex until the age of 14. From that age, Pmax values are lower
in girls than in boys. It also demonstrate that the increase of
Pmax between 7.5 and 17.5 years old is higher in boys than in
girls. Table 1 summarizes the results of the multilevel regression analysis in girls and in boys. It showed that mass, LLV and
age are significant explanatory variable in both sexes and that
in girls, LLV is the parameter which best explains the variance
of Pmax (68%) whereas in boys it is age (57%). Significant
exponential relationships were found between Fopt and LLV in
girls (r2=0.74, p<0.0001) and in boys (r2=0.83, p<0.0001).
ANCOVA indicated that the ordinate and slope of the linear
regressions were not significantly different between girls and
boys. Significant exponential relationships were also found
between Vopt and LL in boys (r2=0.55, p<0.0001) and in girls
(r2=0.41, p<0.0001). ANCOVA indicated that the ordinates
were significantly different (p<0.0001).
Discussion
The results of figure 1 demonstrated that between 7.5 and 17.5
years old, Pmax increased 295% in girls whereas it increase
375% in boys. In girls, LLV was responsible for 68% of the
total explained variance (Table 1). Accurately, it means that
Pmax increase was greatly dependent on quantitative muscular
factors improvement. In boys, age was responsible for 57% of
the total explained variance of Pmax. In the present multilevel
regression analysis, when quantitative muscular factors such as
LLV and mass were significant explanatory variables, the significant main effect of age refers to muscular qualitative factors
which are related to the percentage of type II fibers, glycolytic
ability motor coordination and motor unit activation changes
during the adolescent spurt. It was shown that for the same
LLV, there are no significant differences between boys and girls.
On the contrary, for the same LL, Vopt is higher in boys than in
girls. It demonstrate that the observed gender differences in
Pmax are related to contracting velocity determinants (type II
fiber and motor coordination).
Table 1: Results of the multilevel regression analysis
with log-transformed Pmax as dependent variable and age (years),
lean leg volume (LLV, l) and mass (kg) as explanatory variables.
Figure 1: Relationship between Pmax (W) and age (years) in girls
(°; dashed line) and in boys (▲; black line). Girls: R2= 0.75;
p<0.05;Boys: R2=0.85; p<0.05.
References
Armstrong, N., J. R. Welsman, and M. Y. H. Chia.( 2001). Br J
Sports Med. 35:118-124
Dore, E., M. Bedu, N. M. Franca, O. Diallo, P. Duche, and E. Van
Praagh. (2000). Med Sci Sports Exerc. 32:493-498
Martin, R. J. F., E. Dore, C. A. Hautier, E. Van Praagh, and M. Bedu.
(2003). Med Sci Sports Exerc (under press)
121
revista
19.9.03
0:50
Página 122
LONGITUDINAL STUDY IN PREPUBERTAL CHILDREN
WITH REFERENCE THE LEVEL OF PHYSICAL ACTIVITY
Ihász Ferenc2, Prókai András2, Ildikó Vajda2, Mészáros János2
1
Faludi Judit, Zsidegh Miklós, Farkas Anna, Mészáros Janos
Semmelweis University, Faculty of Physical Education and Sport
Sciences, Hungary
Keywords: somatic developement, aerobic power, physical performance
The aim of the present 5-years longitudinal study was to
analyse the changes in somatic development and cardiorespiratory performance of 7-year-old children, living in higher socioeconomic conditions in one of the districts of Buda.
The children took part in the investigations on their voluntary
base between the years of 1997 and 2002. The written consents of their parents were also collected. Altogether 42 children have been taken part in all the 6 data collections.
For the anthropometric characterisation the Conrad (1963),
Drinkwater-Ross (1980) and Parízková (1961) techniques were
used, all of them are accepted by the international literature.
The biological development of children was assessed according
to the suggestions of Mészáros and Mohácsi (1983). The peak
spiroergometric variable were recorded by Jaeger m-DATASPIR
analyser, and the test exercise was performed on treadmill
(Jaeger 6000 LE). All the children had preliminary practice in
treadmill running.
The means of the anthropometric and peak exercise physiological variables were statistically the same at the time of first data
collection, consequently the possible initial differences may not
restrict the evaluation of the effects of regular physical actívity.
The anthropometric and exercise physiological characteristics
can be divided into two groups by the differences between the
respective means of the two samples and by the directions of
their changes. No significant effects of the regular physical
activity could be observed on the age dependency of mean
height, body mass, plastic index, heart rate, absolute aerobic
power, respiratory exchange ratio, oxygen utilisation, respiratory equivalent.
These observations are inconsistent in part with the publications of Frenkl and associates (1998) and also with our respective hypothesis.
The essential point of view in this relationship is, that the
physical performance and also the efficiency of the physical
work were greater in the active sample during the time of the
final 5 data collections. The distorting effects of sampling error
can clearly be excluded in this respect, since the initial performances were not used as consideration in grouping.
The development of aerobic power, however, cannot be end in
itself. We have to stress for the extremely high aerobic performances relative to body mass do not refer good or excellent
physical performance necessarily.
Our evaluation could be right only in such manner, if we can
qualify and evaluate the exercise physiological fundamentals and
the outcomes (the characteristic physical performances) together.
PHYSIQUE, BODY COMPOSITION AND MOTOR PERFORMANCE IN
HUNGARIAN AND ROMA BOYS
Tatár András1, Zsidegh Miklós2, Mészáros Zsófia2,
122
Ministry of Children, Youth and Sports, Hungary
Faculty of Physical Education and Sport Sciences, Semmelweis
University Budapest, Hungary
2
Introduction
Though no clear agreement exists with respect to the anthropologic origin of different Roma (Roma is the official terminus
technicus for the indication of gypsy) ethnicity, the Roma population is characteristic in almost all of the European countries.
The Roma ethnicity represents the greatest minority within the
population in Hungary. The ratio of Roma ethnicity has doubled during the past 30 years, bringing it to about 9% of the
population in 2003. As a comparison the summarised ratio of
German, Slovakian, Serbian, Rumanian, and other nationalities
combined is less than 9%. The marked increase has two important components. One of them is that more Roma families
have declared their ethnicity during the past national census,
and secondly the birth rate in the Roma families is more than
2.5 times greater than in the Europid groups.
Though the official former politics (between 1945 and 1990)
declared that no differences exist among the nationalities and
ethnic groups of Hungary, nevertheless, the Roma population
lived separately in the settlements, and it has represented the
lowest socio-economic class in Hungary. Anthropometric or
socio-cultural studies were published neither about the nationalities nor the ethnic group of the Hungarian society.
In spite of that the 8th grade elementary school is obligatory
for all Hungarian citizens, including Roma, about 50% of
Roma children do not answer this requirement (though special
schools with adapted curricula, including their Beas language
were organised and adjusted to their special culture), and less
than 10% of the Roma children take part in the secondary
school education. Moreover, only 1-2% enter into the colleges
and universities. The most marked barrier to their elementary
education is that a majority of 6- and 7-year-old Roma children
do not speak the Hungarian language at the necessary level.
More and more Roma families have moved into the centre of
greater settlements (that is, mainstream Hungarian life) during
the past 20 years. However, because of their special life style
basically they could not adapt themselves to the new surroundings. The ratio of unemployment (about 50%) and crime are
the highest among them, consequently their life condition did
not change remarkably. Both unemployment and crime rate are
related to their very low educational level. Though their integration was aimed by all Hungarian governments of the past 50
years, the endogamy is almost solely characteristic among
them, and neither their educational level, nor life standard and
life style changed.
The aim of the present study was to compare the body dimensions, physique, body fat content, and motor performance
scores of Europid and Roma origin boys. By the anthropologic
differences and according to their long lasting social separation,
and living standards, remarkable differences can be supposed
between the compared two groups.
Methods
A total of 1225 volunteer urban, Europid and 435 Roma boys
aged between 9.51 and 13.50 years were recruited for the study.
The subject numbers are not proportionate to the representation
within the population. They ranged between 269 and 342 in the
revista
19.9.03
0:50
Página 123
European group, and 106 and 113 in the Roma sample. It was
extremely difficult to collect the written consents of the Roma
parents. Many of them refused participation without reason, and
the other explanation was, that this comparison gives a new
basis for the additional separation. Height, body mass, shoulder
width, chest depth and -width, lower arm girth, hand circumference and five skinfold thicknesses were measured according to
the suggestions of the International Biological Program (Weiner
and Lourie 1969). Physique was characterised between the
extremes of leptomorphic and picnomorphic body build by the
metric index, and the bone-muscle development by the plastic
index following the suggestions of Conrad (1963). Relative body
fat content was estimated by the modified Parízková (1961)
technique (Szmodis et al. 1976) and the body mass index was
also calculated. Running speed was estimated by the scores in 30
m dash. The best results of the 3 trials were analysed.
Cardiorespiratory endurance was assessed by the results in 1200
m run. Differences between the means were tested by t-tests for
independent samples at 5% level of random error.
Results
Means, standard deviations, and results of comparative statistics are summarised in Tables 1-4. The Europid children were
significantly taller than their Roma age mates in all four compared age groups, however, the respective standard deviations
around the means were the same (Table 1). The investigated
10 and 13-year-old Europid boys were slightly taller than those
in the national representative sample (Eiben et al. 1991). As
we stressed earlier no anthropometric data were published
about the Hungarian-Roma ethnicity. In spite of the significant
differences between the height means the average body masses
were statistically the same consistently, nevertheless the intragroup variabilities were more marked in the groups of Roma
boys (Table 1). The age dependent increases in height and body
mass were significant in both anthropologically different
groups, and no remarkable difference can be supposed between
the speeds of age dependency.
The different height means and the similar body mass averages
theoretically predict the differences among the BMI averages.
The statistical analysis did not prove the theoretical expectation (Table 2). The only difference that can be pointed out in
this respect is the consistently greater standard deviations in
the Roma samples. The increasing BMI trends with age were
significant in both samples. The mean relative body fat contents were between 18.5-19.0% in the Europid age groups; the
body fat content of the Roma children and adolescents were
significantly higher (Table 2). The lowest average in this sample was 21.77% and the highest 23.01%. Beyond the greater
mean body fat content, the intra-group variabilities were consistently greater in the Roma samples. The age dependent fat
increase was not significant in the group of Europid children,
however, an increasing mean trend can be calculated in the
group of Roma boys.
Table 1. Descriptive and comparative statistics for height and body mass
Abbreviations: SD = standard deviation, <5% = difference between
the means is significant, NS = non significant.
Table 2. Descriptive and comparative statistics
for body mass index and body fat content
for metric and plastic indices
for 30 m dash and 1200 m run
Table 3 contains the descriptive and comparative statistics for
the growth type indices. The mean metric indices were significantly more negative in the sample of Europid children, consequently their physique was more linear, more leptomorphic,
although the intra-group variablities were similar in both races.
The average absolute bone-muscle development of the Roma
children was significantly less than those of the Europid boys.
The differences were greater, and were not just attributed to
their shorter body height. No remarkable inter-race variability
was found between the respective standard deviations.
The characteristic means for running speed and cardiorespiratory endurance can be seen in Table 4. The Europid children
and adolescents performed significantly better than the Roma
boys. Interestingly, the standard deviations around the means
were greater in the age groups of the Europid subjects. The age
dependency in 30 m dash was significant in both groups, nevertheless the age group means for 1200 m run in the Roma
sample did not differ significantly.
Discussion
Among the eight variables studied only the stature and metric
index can be attributed to the race differences. The height and
physique variability among various races of same age range
were significant in another investigation (Mészáros et al.
2002). The rate in height growth between 10 and 13 years of
age is high in spite that the peak height velocity cannot be supposed within the observed age range, however, the respective
averages are comparable if the biological maturation level of
the subjects is the same. The observed taller stature of the
Europid children can be attributed to race differences. The patterns of age dependent metric index trends of the two compared races were similar, but the trend lines of the means ran
parallel. Consequently the race differences were marked,
although the three dominant Roma subraces (Beas, Olah, and
XXX) were not separated in this comparison.
The body mass, BMI, and body fat content are more sensitive to
environmental effects than height and physique characteristics
(Bouchard et al. 1997). Consequently the relatively greater body
123
revista
19.9.03
0:50
Página 124
mass and the high body fat content are the consequences of their
characteristic life style, namely definite hypo-activity or sedentarism. Since the marked hypo-activity was also characteristic
during the observation period among Europid children according
to the findings of Laki and Nyerges (2000), we have to evaluate
the differences between the quality of everyday nutrition also. As
it was stressed in the introductory paragraph of this article, the
majority of Roma families represent the lowest socio-economic
class of present day Hungarian society. In such economical circumstances the price and quantity of everyday nutrients are
determinative. It is a returning observation that the members of
poor families are more often fat and obese than those belonging
to middle and higher socio-economic classes (Mészáros et al.
1989, Frenkl and Mészáros 2002). The serious hypo-activity can
be related to the urban status of our subjects. Higher, but not
remarkably high habitual physical activity characterises the rural
children in Hungary (Eiben et al. 1991).
The characteristic hypo-activity or definite sedentarism determines the quality of running performances too. The observed
better scorings of the Europid sample were also lower than
means for non athletic children published 26 years ago (Szabó
1977). The very low level of cardiorespiratory fitness and the
high ratio of body fat content together imply greater risks than
the mentioned anomalies separately (Bouchard 2000).
Although both ratios were high, the distribution of relative
body fat content was about 25% for the Europid boys, and
more than 35% (indicating great obesity) for the investigated
Roma children.
The observed anthropometric and physical characteristics of
Roma children are in close harmony with their low socio-economic status. The possible and necessary solution belongs to
the Roma families just in part, since without effective governmental and social intervention the Roma population reproduces enlargedly the observed unfavourable living conditions.
Acknowledgement
The authors express their gratitude to the Ministry of Children,
Youth and Sports for the financial support of this investigation.
References
Bouchard C (2000). Physical Activity and Obesity. Human Kinetics,
Champaign, Illinois.
Bouchard C, Malina RM, Pérusse L (1997). Genetics of Fitness and
Physical Performance. Human Kinetics, Champaign, Ill.
Eiben OG, Barabás A, Pantó E (1991). Humanbiologia
Budapestinensis, 21: 123.
Frenkl R, Mészáros J (2002). Hippocrates, 4: 5. 294-297.
Laki L, Nyerges M (2000). Kalokagathia, 75th Anniversary, Special
Issue, 24-35.
Mészáros J, Mohácsi J, Farkas A, Frenkl R (1989). Children and exercise XIII. Human Kinetics Publishers, Inc., Champaign, Illinois, 75-80.
Mészáros J, Lee CP, Tatár A, Zsidegh P, Mohácsi J, Frenkl R (2002).
Acta Biologica Szegedinensis, 46: 1-2. 61-65.
Parízková J (1961). Metabolism, 10: 794-807.
Szabó T (1977). Utánpótlás-nevelés, 3: 1-53.
Szmodis I, Mészáros J, Szabó T (1976). Testnevelés- és
Sportegészségügyi Szemle, 17. 4. 255-272.
Weiner JES, Lourie JA (Eds.)(1969). Human Biology. A Guide to
Oxford
124
PHYSIQUE, BODY FAT CONTENT AND MOTOR PERFORMANCE
IN TWINS
Mészáros János, Zsidegh Miklós, Ihász Ferenc, Mészáros Zsófia,
Tatár András, Prókai András, Vajda Ildikó, Mohácsi János
Semmelweis University Budapest, Faculty of Physical Education
and Sport Sciences, Hungary
Keywords: speed, endurance, physique
Introduction
The inheritance of various anthropometric characteristics is different, it depends for instance on the investigated sample size
and age range, however, the available evidence indicate that a
significant proportion of the within-pair variation in size and
physique is genetically determined (Bouchard et al. 1997). The
biologically related persons often have in common similar
measurable phenotypic characteristics, however, by using the
anthropometric somatotyping technique for the description of
physique in male twins had greater heritability indices than in
female twins (Carter and Heath 1990). Gender differences
could be observed also in other morphological variables.
Since the absolute or relative body fat content is the linear
function of energy intake and energy expenditure, no clear
agreement exists among the investigators regarding the importance of genetic factors for body fat content (Garn et al. 1989).
Body composition and skinfold thickness patterning vary with
growth and development, moreover show significant gender
differences from early childhood up to adulthood. The dramatic
increase in the prevalence of overweight, fatness and obesity in
the economically developed countries during the past 4-5
decades also reveals that the non-genetic influences are
extremely important in the development of body fat content.
Estimated heritabilities in various motor performance scores
vary within a very wide range in the early study of Kovar
(1981). A variety of running, jumping, and throwing tasks have
been considered in non-athletic twins. The comparisons suggest a significant genetic effect during childhood and adolescence, but the magnitude of the effect varies among motor performances and among studies. Some investigations suggest
that fine motor performances have a significant genetic component that reaches about 50% of the variation and perhaps more
(Pérusse et al. 1987, Malina 1995, Chatterjee and Das 1995).
Thus, the genetic influence was significantly reduced by habitual physical activity (Malina and Mueller 1981). Although a
great variety of motor perfomance tests are available for estimation of motor qualities, limited data are available for the
inheritance level of simple motor performance scores.
The aim of this investigation was to assess the heritability of
morphological growth type and selected motor performances
in pubertal and postpubertal twins. Comparison of the
results of various assessment procedures can be determined
as a secondary aim.
Methods
A total of 50 Hungarian, non-athletic volunteer twins were
recruited into the comparison. Their calendar age ranged
between 13 and 18 years. Among them 22 were identical (13
boys and 9 girls), and 28 (13 boys and 15 girls) dizygotic
twins. Zygozity was determined by blood and/or placental
analysis. All the pairs were living in the same family. No long
revista
19.9.03
0:50
Página 125
lasting disorders (asthma bronchiale, renal, metabolic, gastrointestinal or endocrine diseases, myocarditis etc.) that may
influence on the physiological pattern of child development
were reported by the parents. The investigated children and
adolescents were the members of middle and high socio-economic class families, thus the possible modifying effects of
chronic under nutrition can be excluded definitely.
Growth type indices, describing the physique between the picnomorphic and leptomorphic extremes were determined by the
anthropometric characterisation of Conrad (1963). This technique is more often used in the Central European countries
and Germany. The metric index is a ratio of chest width and
chest depth corrected by the stature. The plastic index is the
sum of the shoulder width, lower arm girth and hand circumference. This character is one of the absolute estimations of
bone-muscle development, and it has significant correlation
with bone-age and motor performance scores in children and
adolescents. The successive means of growth type indices
describe the age dependent changes in physique and body proportions that is followed by every healthy children.
Body fat content was estimated by the suggestions of Parízková
(1961), and expressed as a percentage of body mass. This procedure requires 10 skinfold thicknesses. In taking the necessary body dimensions the guideline of the International
Biological Program (Weiner and Lourie 1969) were observed.
Running speed was estimated by the scores in 30 m dash.
Reading accuracy: 0.01s. Standing long jump (reading accuracy:
5 cm) and fist ball throw (reading accuracy: 10 cm) were used
for the estimation of explosive strength and arm-trunk-leg coordination. Three trials were performed in these tests, and the
best results were entered into the statistical analysis.
Cardiorespiratory endurance was estimated by the scores in
1200 m run (reading accuracy: 1s). The pairs were physically
tested separately on the same day.
Within-pair linear correlation coefficients were calculated in
the groups of monozygotic and dizygotic twins. Differences
between the correlation coefficients were tested by Z-transformation at 5% level of random error. The level of inheritance
was calculated by two different equations:
long jump and fist ball throw could be characterised by similar
correlation coefficients around 0.50 only. Statistical differences
between the coefficients calculated in the group of mono- and
dizygotic twins were consistently significant.
Table 1. Inheritance in studied variables
Figure 1. Congruence between 30 m dash scores.
Figure 2. Congruence between standing long jump scores.
equation 1: h2 = 2 × (rMZ-rDZ),
equation 2: h2 = (rMZ – rDZ) × (1 – rDZ)-1.
Results
The results of statistical analysis are summarised in Table 1
and the within-pair differences of motor performnaces scores
are shown in Figure 1-4. The vertical axis is scaled by the differences between the first born and second born. The horizontal line in the position of zero value indicates that theoretical
case, when no differences were found between the values of
identical twins. Dots indicates the monozygotyc twins, and the
squares refer to the fraternal twins. According to the published
results in the international literature all the correlations were
significantly stronger in the group of identical twins in spite of
the limited number of subjects. The highest coefficient was
found in body mass (r = 0.93) and the lowest one characterises the relationship between the scores in 30 m dash (r = 0.81)
in the group of identical twins. The pattern of correlations was
only partly similar in the group of dizygotic pairs. The highest
correlation was also found in body mass (r = 0.68), however,
the within-pair similarity of metric and plastic indices, the relative body fat contents and the scores in 30 m dash, standing
Figure 3. Congruence between fist ball throw scores.
125
revista
19.9.03
0:50
Página 126
Figure 4. Congruence between 1200 m run scores.
The estimation of inheritance by the used two various techniques yielded different results. The rank order of estimated
inheritance (4th and 5th columns of Table 1) can be seen in
parenthesis. By using the equation 1 the observed range was
wider (0.28 vs. 0.18), consequently this procedure can be evaluated as more sensitive. The first equation estimated the
strongest genetic effect in metric index (h2 = 0.78) which character is one of the anthropometric descriptor of physique linearity or roundness. Using the second equation the level of
inheritance was similar in stature, plastic index (the indicator
of bone-muscle development) and fist ball throw (h2 = 0.78).
The lowest genetic determination was found by the first equation in body mass (h2 = 0.50). The second equation resulted
the weakest inheritance in 30 m dash (h2 = 0.61). Numerically
similar effect was found in the inheritance of relative body fat
content (h2 = 0.64). The greatest difference between the two
estimates of genetic influences can be observed in body mass
(h2 = 0.50 vs. 0.78).
Discussion
According to the international literature the close genetic influence in stature seems to be obvious, nevertheless the environmental effects are greater in body mass. The observed differences between the correlation coefficients found in mono- and
dizygotic twins in respect of stature and body mass were similar to the cross sectional observations of Wilson (1986). The
very slight differences between the results of the two investigations can be attributed to the various age ranges. The younger
the twins are the smaller the absolute within-pair differences
are in body dimensions. Our subjects were markedly older.
No observations were found in respect of metric index, the linearity character of physique introduced by Conrad (1963).
Since the calculation of relative linearity of anthropometric
somatotype needs the height and the body mass, the metric
index requires the stature and the two chest diameters, these
characteristics (III. somatotype component and metric index)
are not directly comparable. The distorting effect of absolute or
relative body fat content is lower in metric index than in the
relative linearity component of the somatotype (Mohácsi et al.
2001). However, the correlation coefficients for the III. somatotype component of mono- and dizygotic twins published by
Song and associates (1994) were very close to the relationships
found in metric index. The different statistical relationships of
identical and dizygotic twins indicates the significant genetic
effect in the age related development of metric index.
Nevertheless, the roles of genetic and non-genetic factors in
the development of metric index need further investigation
with larger samples, wider age range, and preferably with lon-
126
gitudinal data collection. The observed level of inheritance in
relative body fat content was slightly higher than the findings
of Bouchard and co-workers (1997). This result would be easily related to sampling error in one hand. On the other hand
this finding can be evaluated rather as non-genetic influence.
The familial effects (dietary habits, habitual physical activity
etc.) seem to be stronger in this respect than those of zygozity.
The continuously increasing and nowadays higher than 30%
ratio of fat and obese children in Hungary cannot be attributed
to the genetic background. These non-genetic effects may also
have a role in the biologically similar qualification of the used
two procedures for the determination of inheritance.
The genetic influence on the observed motor performances
were significant irrespective of the technique of calculation.
Interestingly the correlations between the scores of dizygotic
twins were higher than 0.50 in all the four motor tests. They
can be evaluated as being more or less higher than the characteristic correlations in the literature. These relationships do not
inform naturally about the quality of performances. Since the
investigated children and adolescents were not athletes (they
were rather hypoactive or sedentary) the moderate and close
relationships describe the similarity between the weak performances. In contrast to the general expectation (namely the genetic determination in speed performances is stronger) the inheritance in the two running tests (30 m dash and 1200 m run)
were biologically similar and also statistically moderate. The
genetic influence on standing long jump and fist ball throw was
higher than that in running performances. The last two performances contain more technical elements than the runnings,
consequently the better scoring requires more and regular practice. The more or less similar motor performances contain also
the effects of non-genetic factors. Among these the most
important ones are the sedentary lifestyle, and the hypoactivity.
Acknowledgement
The authors express their gratitude to the Hungarian Society of
Sport Science for the financial support of this investigation.
References
Bouchard C, Malina RM, Pérusse L (1997). Genetics of Fitness and
Physical Performance. Human Kinetics, Champaign, Ill.
Carter JEL, Heath BH (1990). Somatotyping development and applications. Cambridge University Press, Cambridge, New York, Port
Chester, Melbourne, Sydney.
Chatterjee S, Das N (1995). Japanese Journal of Physiology, 34: 519534.
Conrad K (1963) Der Konstitutionstypus. Springer Verlag, Berlin.
Garn SM, Sullivan TV, Hawthorne VM (1989). American Journal of
Clin. Nutr., 50: 1308-1313.
Kovar R (1981). Human variation in motor abilities and its genetic
analysis. Charles University, Prague.
Malina RM (1995). Med. Exerc. Nutr. Health, 4: 123-125.
Malina RM, Mueller WH (1981). Human Biology, 53: 163-179.
Mohácsi J, Lee CP, Zsidegh M, Tatár A, Mészáros J (2002). Collegium
Anthropologicum. 26: 142.
Parizková J (1961). Metabolism, 10:794-807.
Pérusse L, Lotrie G, Leblanc C, Tremblay A, Thériault G, Bouchard C
(1987). Ann. Hum. Biol., 14: 425-434.
Song TMK, Pérusse L, Malina RM, Bouchard C (1994). Human
Biology, 66: 453-464.
Weiner JES, Lourie JA (Eds.) (1969). Human Biology. A Guide to
Field Methods. IBP Handbook, No. 9. Blackwell, Oxford.
revista
19.9.03
0:50
Página 127
Wilson RS (1986). Twins: Genetic influence on growth. In: Malina,
R.M., Bouchard, C. (Eds.) Sport and human genetics. Human
Kinetics, Champaign, Illinois, 1-21.
THE CONTRIBUTION OF CLUMSINESS TO RISK FACTORS
OF CORONARY VASCULAR DISEASE IN CHILDREN
Hay John A1, Cairney John2, Faught Brent E1, Flouris Andreas D1
1 Faculty of Applied Health Sciences, Brock University,
St.Catharines, Canada
2 Center for Addictions and Mental Health, University of Toronto,
Toronto, Canada
Keywords: clumsiness, physical activity, obesity
Introduction
Pediatric epidemiology research has suggested that major adult
coronary vascular disease begins in childhood (Berenson et al.,
1997). The purpose of this study was to explore the contribution of clumsiness to risk factors of coronary vascular disease
in children. In 1994, the terms “clumsy child syndrome” or
“specific developmental disorder” was replaced by “developmental coordination disorder” (DCD) based on the recommendations from the International Consensus Meeting on Children
and Clumsiness (Polatajko, Fox and Missiuna, 1995).
Currently, the Bruininks-Oseretsky test is recognized as an
acceptable North American standard for diagnosing DCD.
Since children with DCD have difficulty performing coordinated movements, they are typically characterized as clumsy (Piek
& Edwards, 1997). Initially described in the Diagnostic and
Statistical Manual III (American Psychiatric Association, 1987,
p53), the criteria for DCD was revised in the DSM-IV to
include: “1) a marked impairment in the development of motor
coordination; 2) the impairment interferes with academic
achievement or activities of daily living; 3) the coordination
difficulties are not due to a general medical condition or
Pervasive Developmental Disorder; and 4) if mental retardation
is present, the motor difficulties are in excess of those usually
associated with it”. These criteria further distinguish DCD as a
separate disorder from similar conditions such as apraxia or
developmental dyspraxia (Miyahara and Register, 2000). The
prevalence of DCD in the North American school-age population ranges from 5-10% (Kadesjo and Gillberg, 1999) with a
slightly lower prevalence reported in The Netherlands (Van
Dellen, Vaessen and Schoemaker, 1990). This discrepancy is
due in part to the use of different instruments with varying criteria being used to diagnose DCD in children. According to
Hay and Missiuna (1998), 129,000 Canadian school-aged children may suffer from DCD, however only a fraction of these
cases are identified and referred for functional interventions.
Since motor difficulties initially present outside the classroom
such as recess breaks, DCD children are often excluded from
active play opportunities. This exclusion from other children
has contributed to the label “playground disability” (Hay and
Missiuna, 1998). Of substantial interest, and yet to this
moment uninvestigated, is the attendant fact that DCD compromises physical activity levels. Reports by Hay (1996, 2003)
and others have consistently shown a marked depression of
activity levels among clumsy children. As the prevalence esti-
mates of DCD range from 5 to 10 per cent, this represents a
significant proportion of the pediatric population which has an
impediment to physical activity. This motoric impairment is
rarely considered among the typically ascribed barriers to activity. The motoric impairment of these children is not particularly well addressed by campaigns that promote activity as fun
and or challenging, nor by attempts to make facilities more
common or accessible. These children have learned to avoid
activity since it a source of frutration and failure. Hay has consistently found that clumsy children have significantly lower
generalized self-efficacy toward physical activity and that their
teachers report them as significantly less interested in activity
than their peers. This leaves these children with an impediment to physical activity which goes largely undiagnosed and
almost universally unaddressed. These children are substantially less active than their peers and this would appear to have
major implciations for heart health. The extent to which clumsiness contributes to an elevated risk of coronary vascular disease by mediating lower activity, increased body fat levels, and
lowered aerobic fitness requires further attention.
Methods
A cross-sectional design was used with a convenience sample
of 206 eligible participants (120 males, 86 females).
Questionnaires were administered in each student’s classroom
during regular class times prior to all other testing. Participants
completed the 61-item Participation Questionnaire which asks
children’s actual participation levels in the areas of free-time
play, seasonal recreational pursuits, school sports, community
sports teams and clubs, and sports and dance lessons.
Participation in organized activities encompasses a one-year
period, and free play is recalled from typical pastime choices
(Hay, 1992). Motor proficiency was evaluated using the
Bruininks-Oseretsky short form test (BOTMP-SF). The 14item BOTMP-SF was individually administered to each consenting child in the school’s gymnasium behind a curtained
barrier to ensure confidentiality. Aerobic fitness level was evaluated using the Léger 20-metre shuttle run test, which has
been validated in a school setting for children 6 to 17 years of
age (Léger and Gadoury, 1989). Testing was conducted in the
school gymnasium during regularly scheduled physical education classes. The speed of the last completed stage (maximal
aerobic speed {MAS}) was used to predict the subject’s maximal aerobic capacity (VO2MAX). Maximum aerobic capacity
expressed as the maximum volume of oxygen utilized during
physical activity was predicted using the regression equation:
{[6.592 * (MAS)] – 32.678}. A medical scale-stadiometer was
employed for the initial body composition measures for height
and weight. Body fat was measured using the Bodystat 1500
bioelectrical impedance analyzer (Heyward, 1991).
This study tested a theoretical model linking clumsiness to two
risk factors for coronary vascular disease (percent body fat and
aerobic fitness) through physical activity levels. The authors
incorporated a staged regression approach whereby the outcome variables were regressed on the Bruininks-Oseretsky
score for clumsiness, while controlling for age, gender, height
and weight. In subsequent models, we introduced variables for
physical activity levels including free play and organized activity. A reduction in the coefficient for clumsiness would support
the hypothesis that clumsiness is related to body fat through
the mediating effect of physical activity.
127
revista
19.9.03
0:50
Página 128
Results
Prevalence of DCD in this previously undiagnosed population
was 0.09+0.03. Average age of male and female subjects was
11.5+1.5 and 11.6+1.4 yrs, respectively. In the first part of
the analysis, we examine the effect of clumsiness on aerobic
fitness and whether or not two measures of physical activity
(free and organized activity) can account for the effect of clumsiness on fitness. It should be noted that a regressing measure
on the BOTMP short form suggests progressively significant
clumsiness. We suspected, a priori, that there would be a difference in the effect of clumsiness on fitness by gender. This was
confirmed in a regression model containing an interaction term
for gender by clumsiness. For clarity of presentation, we undertook independent analyses for both boys and girls. In both
analyses, the effect of clumsiness on fitness was significant for
both boys and girls after adjusting for age, weight and height.
The effect was in the anticipated direction, whereby increased
clumsiness was associated with decreased aerobic fitness level.
In Table 1, models 2 and 3, two measures of physical activity
were introduced in the analyses for boys. Together, free play
and organized activity (model 3) reduce the measure for clumsiness by 11%. Only organized play was significantly related to
fitness in the final model. For girls, the introduction of the
activity measures in models 2 and 3 reduced the measure for
clumsiness by 7% (Table 2). A parallel analyses was incorporated in the second part of the analysis by substituting percentage body fat for aerobic fitness level. No significant (p>0.05)
interaction was identified between gender and clumsiness in
the multivariate model. Therefore, we combined the genders
together in the same model (Table 3). After adjusting for gender, age, height and weight, clumsiness was inversely associated with body fat, whereby children with significant clumsiness
demonstrated higher body fat. The introduction of the physical
activity measures in models 2 and 3 reduced the coefficient for
clumsiness by 3%. Neither measure of activity (i.e., free play or
organized activity) was significantly (p>0.05) related to body
fat in the final model.
Table 2. OLS Regression of aerobic fitness on clumsiness
adjusting for age, weight, height and physical activity for girls
* p<0.05
Table 3. OLS Regression of body fat on clumsiness adjusting
for age, weight, height and physical activity for boys and girls
Table 1. OLS Regression of aerobic fitness level on clumsiness
adjusting for age, weight, height and physical activity for boys
** p<0.001, *p<0.05
*** p<0.001, **p<0.01, † p<.10
128
It is widely assumed that habitual physical activity patterns of
children is effective in reducing coronary risk factors (Berenson
et al., 1997; Raitakari et al., 1994). Regular participation in
physical activity has demonstrated a positive correlation with
cardiovascular health. Some of these beneficial effects of physical activity in young adults can be seen in coronary risk factors
including increased HDL cholesterol, decreased serum triglycerides, and body fat (Donahue et al., 1988). Clumsy children
have less self-confidence in physical activities and social skills
(Kadesjo and Gillberg, 1999). Challenges with motor coordination are worsened when the perception of low physical competency or social exclusion results in avoidance or withdrawal
from physical activity (Missiuna, 1994). Since children with
DCD often choose to avoid physical active settings, they may
remain unnoticed in the school system for many years
(Missiuna, 1994). This avoidance of physical activity leads to
long-term health difficulties as the association between
revista
19.9.03
0:50
Página 129
decreased physical activity and increased risk of chronic diseases is well established (Lee and Paffenbarger, 1994; Blair,
1993). Recent preliminary evidence suggests that children
with DCD are significantly less physically active, demonstrate
lower aerobic fitness and are higher in body fat compared to
their non-DCD peers (Hay et al., 2003; Faught et al, 2002).
Our results suggest that participation in physical activity is a
significant mediator in the relationship between clumsiness
and aerobic fitness. Children with significant clumsiness were
less likely to be physically active, which in turn is associated
with lower aerobic fitness levels. This effect was somewhat
stronger for boys than girls. This difference could be attributed
to greater variability in physical activity levels found in boys
compared to girls. This study did not find a mediating effect
for physical activity in the clumsiness-body fat relationship.
Children who are clumsy demonstrate a preponderance for
higher body fat. However, neither free play or organized activity account for this relationship. It could be suggested that
physical activity is more influential on aerobic fitness than
body fat, particularly in boys. Body fat may be better explained
by other factors including diet and genetic predisposition.
Nevertheless, the overall results demonstrate a stronger association between motoric competency and aerobic fitness than body
fat. In conclusion, it is important for parents and educators of
children with DCD to emphasize daily physical activity in order
to improve the risk factor profiles for coronary vascular disease.
References
American Psychiatric Association. (1994). Washington: American
Psychiatric Association.
Berenson, G.S., Srinivasan, S.R., and Bao, W. (1997). Ann N Y
Acad Sci., 28 (817), 189-98
Blair, S.N. (1993). Res Q Exerc Sport, 64(4), 365-376
Donahue, R.P., Orchard, T.J., Becker, D.J., et al. (1988). Am J
Epidemiol, 127, 95-10.
Faught, B.E., Hay, J.A., Flouris, A., Cairney, J. and Hawes, R.
(2002). Can J Appl Physiol, 27, S17
Hay, J. (1992). Clin J Sport Med, 2, 92-201
Hay, J. and Donnelly, P. (1996). Avante, 2, 36-52
Hay, J., Hawes, R. and Faught, B.E. (2003). J Adolesc Health.
(Submitted)
Hay, J. and Missiuna, C. (1998). Can J Occup Ther, 65(2), 64-71
Heyward, V.H. (1991). Champaign, IL:Human Kinetics.
Lee, I., and Paffenbarger, R.S. (1994). Med Sci Sports Exerc, 26(7),
831-837
Léger L.A. and Gadoury C. (1989). Can J Sport Sci, 14, 21-26
Kadesjo, B. and Gillberg, C. (1999). J Am Acad Child Adolesc
Psychiatry, 38(7), 820-828
Missiuna, C. (1994). Adapt Phys Act Q, 11, 214-235
Miyahara, M. and Register, C. (2000). Res Dev Disabil, 21, 367-376
Piek, J.P. and Edwards, K. (1997). Br J Educ Psychol, 67, 55-67
Polatajko, H., Fox, M., and Missiuna, C. (1995). Can J Occup Ther,
62, 3-6
Raitakari, O.T., Porkka, K.V.K., Taimela, S., Talama, R., Rasanen, L.
And Viikari, J.S.A. (1994). Am J Epidemiol, 140 (3) 195-205
Van Dellen, T., Vaessen, W., and Schoemaker, M.M. (1990). Ann
Arbour, MI: University of Michigan Press, 135-52
CARDIORESPIRATORY AND MUSCULO-SKELETAL LOADING
DURING HIGH SCHOOL PHYSICAL EDUCATION
Fairclough Stuart J, Stratton Gareth
School of Physical Education, Sport and Dance, Liverpool John Moores
University, Liverpool, UK
Introduction
It has been suggested that physical education should be the
principal forum for promoting children’s physical activity,
because it is the only element of the school curriculum that
can practically address their health-related physical activity
needs (Strand and Reeder 1996). Support can be lent to this
supposition when one considers that the majority of children
attend physical education lessons, which in secondary schools
at least, are commonly taught within dedicated facilities by
specialist teachers. However, participation in optimal levels of
physical activity during physical education is hindered by the
diverse aims of the subject. The overarching goal should be for
students to take part in appropriate amounts of physical activity during lessons, and become educated with the knowledge
and skills to be physically active outside school and throughout
life (Simons-Morton 1994). However, the emphasis of learning
in any particular lesson may quite legitimately have a motor,
cognitive, social, spiritual, cultural or moral focus, which may
not necessarily be consistent with achieving optimal physical
activity levels. For this reason, it is unrealistic to expect every
physical education lesson to successfully meet health-related
physical activity aims.
Heart rate telemetry and accelerometry are valid measures of
children’s physical activity, which are concerned with different
aspects of this behaviour (Rowlands et al., 1999). Telemetry
assesses the demand placed on the cardiorespiratory system
during a given activity. The linear relationship between heart
rate and energy expenditure then allows an indirect estimation
of physical activity. Conversely, accelerometry measures bodily
acceleration, which places stress on the musculo-skeletal system. Thus, accelerometer counts may serve as a useful indicator
of musculo-skeletal loading during physical activity. Heart rate
and accelerometry data can be used to complement each other
when attempting to evaluate physical education’s contribution
to the cardiorespiratory and musculo-skeletal dimensions of
physical activity. Moreover, both instruments relate well to current physical activity guidelines for young people, which recommend participation in activities to benefit cardiorespiratory
health, and promote musculo-skeletal development (Biddle et
al., 1998). Furthermore, activity levels achieved during physical
education may make a meaningful contribution to help young
people meet recommended physical activity goals (Fairclough,
2003). This investigation assessed high school students’ physical activity during a selection of physical education lessons,
using heart rate telemetry and accelerometry. The major aim
was to establish the extent of cardiorespiratory and musculoskeletal loading during different activities.
Methods
Fifty five high school students (33 boys, 22 girls, aged 13.0 ± 0.9
years) volunteered to participate in this study. Students’ physical
activity during physical education lessons was monitored using
heart rate telemetry (Vantage XL; Polar Electro Oy, Kempele,
Finland), and triaxial accelerometry (Tritrac-R3D; Hemokinetics
Inc., Madison, WI). Students were fitted with the equipment
while changing into their physical education uniforms.
Telemeters were attached by fitting a lightweight chest strap
129
revista
19.9.03
0:50
Página 130
(transmitter) and wristwatch (receiver), which was covered by a
wristband. Accelerometers were placed in sealed pouches that
were attached to adjustable fabric belts. Each participant wore
the belt with the pouch positioned on their right hip, secured
inside the waistband of their shorts or tracksuit pants. Before
lessons commenced the telemeters’ and accelerometers’ internal
clocks were synchronised with that of the computer system to
which they would be interfaced for data analysis. At the end of
the lessons both instruments were removed from each child and
returned to the laboratory, where they were interfaced with a PC
and data were downloaded for analyses.
Heart rate reserve (HRR) was calculated for each participant
using resting and maximum heart rate values. Heart rates ≥
50% HRR represented health-enhancing moderate-to-vigorous
physical activity (MVPA HR) (Stratton 1997). Mean activity
heart rate (ActHR, i.e., mean heart rate minus resting heart
rate, (Welk and Corbin, 1995)) was also calculated to provide a
raw measure of cardiorespiratory load. Accelerometer vector
magnitude values ≥1000 counts • min-1 represented the threshold for MVPAAC (Rowlands et al., 1999). In addition, mean vector magnitude counts • min-1 were included as a raw measure
of musculo-skeletal loading during lessons. Students were
monitored during twenty seven physical education lessons.
These were categorised as invasion team games (e.g., soccer,
basketball, hockey, etc.), net games (e.g., badminton, short tennis, etc.), movement activities (e.g., gymnastics, dance, etc.)
and running/fitness lessons. The latter category was made up
of athletics lessons (all with a focus on running events) and
lessons where circuit or station training and running activities
were the main focus. As sample sizes in each activity category
were unequal, and some of the data were not normally distributed, non-parametric Kruskal-Wallis ANOVA’s calculated differences in the amount of cardiorespiratory or musculo-skeletal
loading during the different activities. Post-hoc Mann-Whitney
U tests determined where identified differences occurred. To
control for familywise error the Bonferroni correction procedure was applied, which resulted in an acceptable α level of
0.008. Although differences in boys and girls physical activity
levels have previously been reported, their data were not treated separately in this study because of the limited sample size
within each physical education activity.
part in invasion game and running/fitness lessons engaged in
significantly more activity than those who were taught movement activities and net games (significance values ranged from
p < 0.0001 to 0.004). Figures 1 and 2 provide a composite representation of these data.
Figure 1. ActHR and counts • min-1 during different
physical education activities.
** Counts • min-1 during invasion games > net games (Z= -3.70,
p < 0.0001) and movement activities (Z = -5.09, p< 0.0001).
ActHR during invasion games > net games (Z= -3.40, p = 0.002)
and movement activities (Z = -4.03, p < 0.0001).
†† Counts • min-1 during running/fitness activities > net games
(Z = -2.86, p = 0.004) and movement activities (Z = -4.08,
p < 0.0001). ActHR during running/fitness activities >
movement activities (Z = -3.23, p = 0.001).
Figure 2. Percentage of lesson time engaged in MVPAHR
and MVPAAC during different physical education activities.
Results
Participants’ descriptive data are described in table 1. As expected, raw and adjusted physical activity values highlighted that
boys were more active during physical education than girls.
** MVPAHR during invasion games > movement activities
(Z = -3.50, p< 0.0001). MVPAAC during invasion games >
movement activities (Z = -5.09, p < 0.0001).
†† MVPAHR during running/fitness activities > movement activities
(Z = -2.58, p = 0.01). ). MVPAAC during running/fitness activities
> movement activities (Z = -3.68, p < 0.0001).
Table 1. Descriptive data of participants.
Differences in activity levels during PE activities were consistent, regardless of measurement variable. Students who took
130
Discussion
This investigation used heart rate telemetry and accelerometry
to assess the extent to which a range of high school physical
education lessons loaded the students’ cardiorespiratory and
musculo-skeletal systems. It is evident that the invasion game
and running/fitness activities monitored were more able to
engage the students in health-enhancing physical activity than
net game and movement activities. These findings are supported by previous investigations that employed heart rate teleme-
revista
19.9.03
0:50
Página 131
try (Stratton 1997) and systematic observation (McKenzie et
al. 1995). The nature of invasion games and running/fitness
activities place a greater requirement on the students to be
constantly moving, either as part of a team dynamic, or to
accomplish a set task. Therefore, these activities emphasise full
body movement, which places a large amount of stress on the
major muscle groups. For these reasons, both activities
engaged students in MVPA, regardless of measurement instrument, for approximately 50% of lesson time, which is the target recommended in the UK (Harris 2000) and US (USDHHS
2000). Conversely, net games and movement activities place a
greater emphasis on motor skill and aesthetic performance,
respectively, and as a result provided fewer opportunities for
activity engagement.
Although there were significant differences in the amount of
time that the activities promoted MVPAHR and MVPAAC, the
standard deviation values indicate the large variability in range
of time spent in these thresholds. Although the most active
students met the 50% of lesson time criteria in each of the
activities (with the exception of movement activities), the least
active students experienced MVPA for only ~30% (invasion
games) to ~10% of lesson time (movement activities). This
illustrates the differences in physical activity participation
within and between different physical education activities,
which are commonly attributed to inter-individual, pedagogical
and environmental differences. Moreover, the accelerometer
standard deviation values were generally smaller than for the
heart rate data. Compared to the heart rate data, it is possible
that the accelerometer data provided a more accurate representation of the students’ activity. This may be because during
inactive parts of the lessons, students’ heart rates remained
elevated for a period of time before decreasing to resting levels.
As physical education lessons are characterised by intermittent
periods of activity and inactivity, due to the pedagogical
processes taking place (i.e., organising, instructing, demonstrating, etc.), it is likely that this lagged heart rate response
occurred on a number of occasions. In contrast, accelerometers
measured only the movement that took place, regardless of any
physiological processes that were occurring.
These data have revealed that some physical education activities are more likely to stress the cardiorespiratory and musculo-skeletal systems more effectively than others. From a health
perspective this information should be used to inform curriculum design. As students progress through their secondary
school years, many students’ interest in physical activity tends
to wane. It may be appropriate for students to experience a
greater proportion of health-enhancing activities during these
years, to compensate for any decrease in activity levels outside
of school. However, these lessons would have to be meaningful
and enjoyable, in order for students to maintain a positive attitude towards physical activity participation once they have left
compulsory education.
Conclusion
This investigation has revealed that during secondary school
physical education lessons, activities that emphasise full body
movement over consistent time periods are able to load the
cardiorespiratory and musculo-skeletal systems to recommended levels. While all activities have the potential to
achieve this, contextual factors that are difficult to control for
in the fluid physical education environment preclude this from
happening frequently. If health-enhancing physical activity is
recognised as an important physical education goal, then findings such as these should inform future curriculum design,
especially with students who are in the middle and upper
years of secondary education.
References
Biddle S., J. F. et al. (1998). Young and Active? Young People and
Health-Enhancing Physical Activity. Evidence and Implications
Corbin C. B. and Pangrazi, R. P. (1998). Physical Activity for
Children: A Statement of Guidelines
Eston R. et al. (1998). J. App. Physiol. 84(4): 362-371.
Fairclough S. (2003). Br. J. Teach. Phys. Ed. 34(1): 40-45.
Harris J. (2000). Health Related Exercise in the National Curriculum:
Key Stages 1 to 4.
McKenzie T. L. et al. (1995). Res. Q. Exerc. Sport 66(3): 184-193.
Rowlands A. V. et al. (1999). J. App. Physiol. 86(4): 1428-1435.
Simons-Morton B. G. (1994). In: R. R. Pate and R. C. Hohn (Eds.).
Health and Fitness Through Physical Education. 137-146.
Strand B. and Reeder S. (1996). JOPERD 67(3): 41-46.
Stratton G. (1997). J. Teach. in Phys. Ed. 16: 357-367.
USDHHS (2000). Healthy People 2010: Understanding and
Improving Health.
Welk G. and Corbin C. B. (1995). Res. Q. Exerc. Sport 66(3): 202209.
ENERGY INTAKE AND EXPENDITURE OF HIGH AND LOW ACTIVE
CHILDREN
Montfort Veronica, Williams A. Craig, Armstrong Neil
Children’s Health and Research Centre, University of Exeter, UK
Keywords: energy intake, energy expenditure, children
The effects of different levels of energy expenditure (EE) on
energy intake (EI) are not fully understood, especially in young
people. Therefore, the aim of this study was to compare the EI
between a high and a low active group of children. Two hundred
children participated in a physical activity survey (adapted from
Cale, 1993). Boys and girls classified with the lowest and highest EE scores (kcal.kg-1.d-1) were then invited to participate further in the study. On three days (Sunday, a physical education
day (PE) and a control-day, without PE) 34 boys and girls 12±1
years old again completed the same physical activity questionnaire and reported their food intake (24-hours recall). Body
mass did not differ between the low active (47±5 kg) and the
active (48±11 kg) groups (p>0.05). Average EE (3 days) was
significantly greater in the active group compared to the low
active group, 1922 ± 415 kcal.d-1 and 1632±198 kcal.d-1,
respectively (p<0.05). The children expended on average more
energy during the PE-day 1844 ± 401 kcal.d-1 compared to
Sunday 1729 ± 339 kcal.d-1 (p<0.05) and the control day 1711
± 354 kcal.d-1 (p<0.01). EE was also greater between both
activity groups during PE and the control-day (p<0.05). EI (3
days) tended to be lower in the low active group 2121 ± 361
kcal.d-1 compared to the active group 2470 ± 542 kcal.d-1
(p<0.06). However, only on the PE-day was EI higher in the
high active group 2485±635 kcal.d-1 compared to the low active
group (2035±491 kcal.d-1) (p<0.05). This difference was associated with a higher carbohydrate intake (p<0.05). In both
131
revista
19.9.03
0:50
Página 132
activity groups a positive energy balance (EB = EI - EE) of ~
500 kcal.d-1 was observed. However, during the PE-day children
had the lowest positive energy difference (p>0.05). Despite
higher EE on the PE-day it was not enough to compensate for
the higher EI. This lower positive energy balance on a PE-day
suggests a weak but possible mechanism of body mass control.
PHYSICAL ACTIVITY: SOCIO-ECONOMICAL DIFFERENCES
IN FLEMISH YOUTH
Philippaerts Renaat1, Matton Lynn2, Wijndaele Katrien1,
De Bourdeaudhuij Ilse1, Taks Marijke2, Lefevre Johan2
1 Department of Movement and Sports Sciences, Ghent University,
Gent, Belgium
2 Department of Sports and Movement Sciences, KULeuven,
Leuven, Belgium
Keywords: physical activity, computer-assisted questionnaire,
adolescents
Introduction
It is well documented that a sedentary lifestyle is an important
risk factor for obesity and other health-related fitness characteristics. Studies have also indicated that there is a positive
association between the socio-economical and the physical
activity status of adults. However, the concept of socio-economical status has been used in different ways. The most used
measurements of socio-economical status are income, educational level, and profession (Pill et al., 1995; Chinn et al., 1999;
Lindström et al., 2001). The differences between socio-economical and socio-professional status are rather small. Most of
the studies focused on the relationship in adults. However, few
studies investigated this relationship in youth. A Dutch study
confirmed the positive association between socio-economical
status of the father and the children’s physical activity.
Children’s behaviour was less healthy (sedentary lifestyle)
when the father had a job in the lower professional classes
(Van de Mheen et al., 1998). The same relationships were
found in other countries (Haglund 1984; Sallis et al., 1996;
Scheerder et al., 2002). However, some other studies did not
find an association between socio-economical status and physical activity (Aaron et al., 1993; Mota & Silva, 1999; West et al.,
2002). The aim of this study was to investigate the relationship
between the socio-economical status of the family and the
physical activity level in Flemish adolescents.
Methods
In total 6.117 adolescents (2.379 boys and 3.738 girls between
12 and 18 years) participated in this study. Physical activity was
measured by means of a computer-assisted questionnaire.
Activity indices included moderate and heavy activities (frequency per week), sport participation during leisure time
(h/week), passive and active transport (h/week, school and
leisure time together) and total physical activity (h/week). Total
physical activity included physical education and sport participation in school, active transport, sport participation during
leisure time, and dancing during night life. Watching TV and
computer business (h/week) were included as a measure of
inactivity. Socio-economical status (3 levels: low, middle and
132
high) was derived from the professions of the parents. Two-way
ANOVA’s with age (7 levels) and socio-economical status (3
levels) as independent factors were used in boys and girls separately. The 0.05 and 0.01 significance levels were used.
Results
In boys, physical activity indices showed no significant differences between the socio-economical levels, except for inactivity
(table 1). Boys from the low socio-economical level spend 26.4
h/week on sedentary behavior, compared to 24.4 h/week for
the boys from the high level (p<0.05). Passive transport
showed a significant age effect with the highest values at older
ages (p<0.01). In girls, the differences in physical activity
indices according to socio-economical status were more pronounced (table 2). Differences were found for all physical
(in)activity variables, except for active transport. Girls from the
low socio-economical level had lower values for physical activity and higher values for physical inactivity, compared to their
peers from the middle and high level. Clear age effects were
found for moderate and heavy activities, and passive transport.
Older girls had lower values for moderate and heavy activities,
and higher values for passive transport. Moreover, interaction
effects (group x age) indicate the biggest drop in the physical
activity values (frequency of heavy and moderate activities, and
sport participation) for the girls from the low socio-economical
level. The oldest girls from the low, middle, and high socioeconomical levels are participating on average respectively 1.1
(±1.0), 1.3 (±1.4), and 2.0 (±1.9) times per week in heavy
activities (of at least 20 minutes). The same trend has been
observed for the number of days participating in moderate
activities (at least 60 minutes per day), respectively 0.9 (±1.0),
1.6 (±1.5), and 1.7 (±1.8) days per week.
Discussion
The present data clearly show higher values for physical activity in boys compared to girls, which is clearly documented in
previous studies (Aaron et al., 1993; Lindquist et al., 1999;
Sallis et al., 1999; Aarnio et al., 2002). Girls are still more
prone to sedentary behavior, even in the beginning of the third
millennium. Also the decline in physical activity with older age
has been documented previously (Caspersen et al., 2000;
Telama & Yang, 2000; Trost et al., 2002).
In this study, the socio-economical status of the children was
derived from the professions of the parents. Although the
socio-economical status can be defined in several ways, the
present method also had been used in some other studies.
However, studies focusing on the relationship between physical
activity and socio-economical status in children and youth
remain scarce.
The main results indicate that there still is a positive association between socio-economical status and physical activity in
Flemish adolescent girls, which was not confirmed in boys. The
impact of the socio-economical status of the family on the physical activity of the children should not be underestimated. First,
the relationship between physical activity and socio-economical
status in adults has been documented. Kawashi et al. (1997)
found that families with low income less invest in social capital
like education and health care. Second, some studies concluded
that children from lower socio-economical status experience
financial shortage which possibly obstructs sports club membership (Sallis et al., 1996; Van de Mheen et al., 1998).
In conclusion, children and adolescents from Flemish families
revista
19.9.03
0:50
Página 133
with lower socio-economical status are less physically active
than their peers from a higher socio-economical level.
Moreover, physical activity programs and promotion should pay
special attention to girls.
Table 2: Differences in physical (in)activity in Flemish girls
in relation to their socio-economical status (SES).
Table 1: Differences in physical (in)activity in Flemish boys
in relation to their socio-economical status (SES).
Values are means ± SD; * p<0.05; ** p<0.01;
>< indicates differences between groups
Acknowledgements
This study was financially supported by BLOSO, Flanders (IOSproject 2001).
Values are means ± SD; * p<0.05; ** p<0.01;
>< indicates differences between groups
References
Aarnio M et al (2002). Scand J Med Sci Sports 12: 179-185
Aaron DJ et al (1993). Med Sci Sports Ex 25: 847-853
Caspersen CJ et al (2000) Med Sci Sports Ex 32: 1601-1609
Chinn DJ et al (1999). J Epidemiol Com Health 52: 191-192
Haglund BJA (1984). Scan J Soc Med 12: 155-164
Kawashi I et al (1997). Am J Pub Health 87: 1491-1498
Lindquist CH et al (1999). Prev Med 29: 305-312
Lindström M et al (2001). Soc Sci Med 52: 441-451
Mota J, Silva G (1999) Sport, Education and Society 4: 193-199
Pill R et al (1995). J Epidemiol Com Health 49: 28-32
Sallis JF et al (1996). J Clin Epidemiol 49 : 125-134
Sallis JF et al (1999). Med Sci Sports Ex 32: 963-975
Scheerder J et al (2002). Sport en Maatschappij 1: 1-160
Telama R, Yang X (2000). Med Sci Sports Ex 32: 1617-1622
Trost SG et al (2002) Med Sci Sports Ex 34: 350-355
Van de Mheen H et al (1998). Int J Epidemiol 27: 431-437
West P et al (2002). Soc Sci Med 54: 607-619
133
revista
19.9.03
0:50
Página 134
PHYSICAL FITNESS AND SOCIO-ECONOMIC STATUS
IN CHILDREN AND YOUTH. THE MADEIRA GROWTH STUDY
College of Kinesiology, University of Saskatchewan, Saskatoon, Canada
Keywords: physical activity, accelerometer, self-report
Freitas Duarte Luís1, Maia José AR2, Beunen Gaston3,
Lefevre Johan3, Claessens Albrecht3, Marques António2,
Rodrigues António4, Silva Celso4, Crespo Maria5, Thomis Martine3
1 Department of Physical Education and Sports,
University of Madeira, Portugal
2 Faculty of Sport Sciences and Physical Education,
3 Faculty of Physical Education and Physiotherapy,
Katholieke Universiteit Leuven, Belgium
4 Centro Hospitalar do Funchal, Madeira, Portugal
5 INE, Portugal
Keywords: physical fitness, socioeconomic status, The Madeira Growth
Study
The main purpose of this study was to investigate the associations between socioeconomic status (SES) and physical fitness
levels in children and youth from the Autonomus Region of
Madeira. A stratified sample of 507 students (251 girls, 256
boys), aged 8 to 18 old, including 5 cohorts (8, 10, 12, 14 and
16) was followed during three consecutive years (1996, 97 and
98) using a mixed longitudinal design.
Physical fitness was assessed with the Eurofit test battery. SES
was evaluated with a questionnaire developed by the
Portuguese Institute of Statistics. Stratification of socioeconomic groups was done with the Graffar method identifying
three groups: low, average and high SES. ANOVA was used to
test for differences among SES groups. For all calculations SAS
was used.
Boys from the low SES group are more proficient than the high
SES group in sit and reach, bent arm hang, standing long jump
and 12 minutes walk/run for some age intervals. In contrast,
the high SES group presents better results than the low SES
group in sit ups, shuttle run and handgrip. For girls, differences
are virtually non-existent. For standing long jump, sit ups, and
shuttle run the results are better for the high SES group. In
flamingo balance, the average and low SES groups show better
performance than the high SES group at 7 to 9 years old.
Conclusions: (1) SES correlations are more pronounced in boys
than in girls; (2) physical fitness levels are not always different
between the SES groups, consequently there is no clear trend
favouring high SES. These results call for a more detailed
analysis looking at possible interactions of SES with biological
maturation and motivation for sports participation that may
induce relevant changes in physical fitness. It is also suggested
that familial and genetic studies could provide more profound
insight into the complexities of relating SES with physical fitness and physical activity.
Introduction
Self-report surveys are widely used to assess physical activity
behaviour in various populations because of their relatively low
cost and participant burden. However, due to suspected memory
errors in younger children (< 10 years-old), the validity of these
instruments has been called into question (Montoye et al.,
1996). The Physical Activity Questionnaire for Older Children
(PAQ-C) was developed to assess physical activity in schoolchildren (ages 8 to 14 years) during the school year (Kowalski et
al., 1997). This is a 10-item questionnaire based on sport participation and activity anchored to a school day. The responses
from the PAQ-C are averaged and a score from 1 (low activity)
to 5 (high activity) is derived. The PAQ-C has become a widely
used instrument to assess physical activity in children, however,
the questionnaire has only been validated on contemporary living Canadian children. The validity of the PAQ-C to assess physical activity in children living in different cultures has not been
explored. Communities of Old Order Mennonites (OOM) in
Canada who live a traditional rural lifestyle without the modern
conveniences of contemporary living (e.g. no motorized vehicles,
TV, radio, computers, video games, organized sport) represent
an ideal group to test how robust the PAQ-C is for assessing
physical activity in children. Therefore, this study evaluated the
concurrent validity of the PAQ-C, when compared to accelerometry, to assess physical activity in children living traditional
(OOM) and contemporary lifestyles.
Methods
The physical activity behaviour of 9- to 12-year-old boys and
girls was measured using the MTI accelerometer and the PAQC. One hundred and twenty-four Old Order Mennonites
(OOM) were compared to both rural (n=165) and urban
(n=110) dwelling children. The OOM live a traditional lifestyle
whereas the rural and urban children live a contemporary
Canadian lifestyle. Seven consecutive days of minute-by-minute
objective physical activity measurements were obtained using
accelerometry with the PAQ-C administered on the final day.
Results
There were no significant differences in mean PAQ-C scores
between groups (OOM=3.05, rural=3.00, and urban=3.03).
Correlation coefficients between PAQ-C scores, average
accelerometer movement counts per minute (cnts/min), minutes
of moderate (3-6 METS) physical activity per day (MPA), and
minutes of moderate and vigorous (3+ METS) physical activity
per day (MVPA) were determined for each group (Table 1).
Table 1: Correlation matrix showing the relationships
among PAQ-C scores and direct accelerometry measures.
VALIDITY OF THE PAQ-C SELF-REPORT PHYSICAL ACTIVITY
QUESTIONNAIRE FOR CHILDREN LIVING TRADITIONAL
VS CONTEMPORARY LIFESTYLES
* significant correlations at p < .05
Tremblay Mark S, Barnes Joel D, Esliger Dale W,
Copeland Jennifer L
134
The results suggest that the PAQ-C instrument is not valid for
revista
19.9.03
0:50
Página 135
use with traditional societies like the OOM. Because the PAQC is designed to measure institutionalized forms of physical
activity, it may fail to capture the activities of daily living relevant to the OOM population. Additionally, the PAQ-C may not
be a valid measure of physical activity behaviour for urban
dwelling children because of the tendency of some children to
over-report their participation in physical activity. When the
children with the top 10 PAQ-C scores from each group were
analysed, the urban children had significantly higher PAQ-C
scores compared to the OOM children, yet their objective physical activity measurements were no different. This study highlights the importance of ensuring the cultural appropriateness
of measurement isnstruments when performing research.
This research was supported by the Canadian Population
Health Initiative of the Canadian Institute for Health
Information.
References
Montoye HJ, Kemter HCG, Saris WHM, Washburn RA (1996).
Measuring physical activity and energy expenditure. Human Kinetics.
Kowalski KC, Crocker PRE, Faulkner RA (1997). Ped. Exerc. Sci.
9:174-86.
ENERGY EXPENDITURE OF SEDENTARY ACTIVITIES IN YOUTH
Pearce Patricia F1, Harrell Joanne S1, McMurray Robert G2,
Pennell Michael3
1
School of Nursing, 2 Department of Exercise & Sport Science,
School of Public Health
University of North Carolina at Chapel Hill, Chapel Hill,
North Carolina, USA
3
Keywords: sedentary activities, leisure activities, energy expenditure
Introduction
Although investigation of moderate and vigorous activities is a
primary focus of much research, increasing sedentariness among
children and youth is reported and there is a documented need
to understand more about the energy expenditure of sedentary
activities (Marshall et al., 2002). A highly sedentary lifestyle is
considered a major contributing factor to non-communicable diseases (e.g., heart disease, type-2 diabetes, and some cancers) in
many countries. With increasingly sedentary lifestyles comes a
parallel growing burden in terms of personal, social, and overall
economic burden, thus there is a global concern regarding the
prevalence of a sedentary lifestyle (World Health Organization:
55th World Health Assembly, Mar 27, 2002).
Inactivity has been shown to start as early as 8 years of age and
inactivity is more likely than a highly active lifestyle to track, or
persist into adulthood (Kimm et al., 2002). Further, when large
amounts of time are spent in sedentary pursuits, there is less
time for more vigorous activities (Marshall et al., 2002).
Increased sedentariness is documented in everyday leisure activities, as well as in school, where children spend a preponderance of their time: A large national study demonstrates an
average of only about 25 minutes of moderate to vigorous PA
per week in PE classes per week, well under the Healthy People
2010 goals for frequency and intensity of PA (The National
Institute of Child Health and Human Development Study of
Early Child Care and Youth Development Network, 2003). In
the Cardiovascular Health in Children and Youth (CHIC) study,
homework, reading, video games, and TV watching were among
the most common activities reported in children and youth ages
8-17 (Bradley et al., 2000). Of these common childhood activities, TV watching has been studied most often. Reports of time
spent watching TV vary from as little as 1 or 2 hours a day
(Hernandez et al., 1999;Lindquist et al., 1999), which is similar
to the 5 to 15 hours per week reported by Robinson (1999), to
a report of 23 hours/week (Faith et al., 2001).
If we can understand more precisely the energy expenditure of
activities considered sedentary and in which children participate
regularly, we can gain a more complete understanding of sedentariness. An improved understanding of sedentary activities in
children can aid in the development of interventions for reallocation of sedentary activities to a higher level of energy expenditure. Reallocation of even small numbers of activities to those
that expend more energy can support increases in overall energy
expenditure (Blair et al., 1992;Marshall et al., 2002). In adults,
TV viewing is estimated to be at the same energy expenditure
as rest, with a MET of 1.0 (Ainsworth et al., 2000). But is this
true for children and adolescents? Energy expenditure (EE) for
sedentary activities in children and youth is primarily based on
estimates. More precise measurement of these activities is
needed to understand the contribution of sedentary activities to
total energy expenditure, as well as to provide a more informed
base for intervention development.
The primary purpose of the Energy Expenditure of Physical
Activity in Youth Study (EEPAY) was to determine energy
expenditure in terms of oxygen uptake, caloric cost, and metabolic equivalent (MET) level of activities common to children
and adolescents (ages 8-18), to evaluate the differences by age
and gender, and to compare results with published METs of the
Compendium (Ainsworth et al., 2000). This presentation gives
data from a subset of the activities measured in the EEPAY
study. The purpose is to evaluate energy expenditure of common sedentary activities and to determine if VO2 differences of
sedentary activity are (a) significantly different from energy
expenditure at rest, or (b) if they differ by gender. The activities examined are TV viewing, video games (while seated and
while standing), reading, planning a board game, and taking a
computerized math test.
Methods
All procedures were approved by a multiple assurance Internal
Review Board. Written informed parental consent and child
assent were completed by all participants. Measurements were
performed at the Applied Physiology Laboratory at the
University of North Carolina. The study involved 317 children
and youth, ages 8-18, with at least 10 subjects of each age and
gender; that is, there were at least 10 boys and 10 girls who
were aged, 8, aged 9, etc. Overall, 47% of the subjects were
female and 53% male.
Self-administered questionnaires were used for age, sex, and
racial affiliation and the Pubertal Development Scale (PDS) was
used to determine self-reported pubertal status. The PDS is a
scale that is widely used for determination of pubertal status and
has been validated with physician-based ratings of pubertal
development (Petersen et al., 1988), by interview assessments of
maturity (Brooks-Gunn et al., 1987) and with self-reports using
picture comparisons (Petersen et al., 1988). Internal consistency
135
revista
19.9.03
0:50
Página 136
reliability of the PDS ranges from a Cronbach alpha of 0.68 to
0.83 (Brooks-Gunn et al., 1987;Petersen et al., 1988).
We measured oxygen uptake (VO2) with a portable metabolic
system (COSMED K4b2), which is documented to accurately
measure energy expenditure (McLaughlin et al., 2001).
Consistency for breath, CO2 and O2 were established.
Measurements were taken at rest, and during 6 sedentary activities: board games, math test, self-selected homework or reading, a computer-adaptive math test, watching TV, and two types
of non-violent video games (a seated Nintendo game and arcade
style video games, completed while standing). Each of the
activities was performed for 10 minutes, with a 5 minute break
between the activities. The activities were done in the same
manner by all subjects, following a carefully designed protocol.
Subjects were familiarized with the portable metabolic system
and instructed in all procedures and activities by trained
research assistants. Data were collected breath-by-breath and
later were averaged over the data collection period to provide
the mean VO2 for each activity. One of the investigators (RGM)
reviewed the graphic print-outs of the data for all subjects to
eliminate artefacts and assure that steady state was reached for
all activities. To further assure steady state, the first two minutes and last minute of data for each activity were excluded.
Thus data were analyzed for 7 minutes of each activity.
Analyses included descriptive statistics for demographic data,
ANOVAs to determine age and gender differences, paired t-test,
and two-sample t-tests for assessment of gender differences.
Because of VO2 similarities across ages, overall age groups were
identified and results are provided for age-group rather than for
each age. The age groups varied slightly for boys and girls,
most likely because girls reach physical maturity at an earlier
age and boys. For girls, group 1 = 8-11 years; group 2 = 12-14
years; group 3, 15-18 years. For boys, group 1 = 8-12 years;
group 2 = 13-15 years; and group 3 = 16-18 years.
Results
The results are shown overall, with boys and girls combined, in
Table 1. VO2 differed significantly across age groups for all
activities (p<0.0001 from one-way ANOVA). A post hoc test
(Student-Newman-Kuels) showed that VO2 decreased significantly (p<.05) with increasing age group (see Table 1).
As shown in Table 2, there were some differences in EE by gender. VO2 was slightly, but non- significantly greater in males for
all but one activity. When using a Bonferroni correction for multiple analyses, the only significant difference by gender was for
VO2 during standing video games, which was higher for boys
(7.5 ml/kg/min, sd ±2.3) than girls (6.6ml/kg/min sd ±2.4).
Table 2: Mean VO2 (ml/kg/min) for each Gender
Because most values were very similar by gender, we looked at
the difference between EE at rest and EE during each of the 6
sedentary activities. After Bonferroni correction, all sedentary
activities except TV were slightly, but significantly greater than
EE at rest (see Table 3). The EE during TV watching
(ml/kg/min: girls 5.0 ±1.5; boys 5.3 ±1.5) was essentially the
same as that during rest (ml/kg/min: girls 4.9 ±1.5; boys 5.1
±1.4). On average, subjects expended the most energy while
playing arcade video games and board games (see Table 3).
Table 3: Difference between energy expenditure
during a sedentary activity and that of resting
Table 1: Mean VO2 (ml/kg/min) for each Age Group
In addition we examined the METs for these sedentary activities by dividing the EE of each subject during these activities
by his or her EE at rest, on a gender specific basis. For both
genders there were no significant differences in METs for most
activities: MET was 1.3 for board games, 1.2 for the math test,
1.1 for reading, 1.0 for TV watching, and 1.2 for sitting video
games. There was a gender difference in METs during standing
video games (MET was 1.4 for girls and 1.5 for boys).
Discussion
The results of this study indicate there are minor differences in
EE across sedentary activities, with significant difference across
age groups for arcade and video games for each activity. For
both arcade and video games, a significant decrease in VO2
with increasing age group is demonstrated. The EE during TV
watching is very similar to the EE during rest, confirming relat-
136
revista
19.9.03
0:50
Página 137
ed findings regarding the low level of energy expenditure related to TV watching (Klesges et al., 1993). Thus, selective
reduction of TV watching may be a promising intervention
component to increase EE, even if replaced only with other
sedentary activities of a slightly higher EE level.
On average, subjects expended more energy while playing arcade
video games and board games than while resting (2.1 and 1.4
ml/kg/min more energy respectively), with males expending
more energy while playing arcade games than females, although
the gender difference is not statistically significant. Although
small differences, this finding underscores the importance of
conceptualizing TV viewing separately from videogames or computer activity. There is documentation of significantly different
amounts of time spent in these activities among children and
youth (Hernandez et al., 1999). The findings that board games
use a little more energy than similar sedentary activities may be
related to the fact that these were competitive games, played by
the child with one of the research assistants.
Although it is recommended that all children and youth participate in moderate to vigorous activities on a regular basis to
establish a healthy lifestyle, a documented rise in a sedentary
lifestyle mandates better understanding of sedentary activities.
These data further understanding of 6 sedentary activities of
children and youth. If precise information regarding EE is
needed, these measurements can be used. Understanding the
energy expenditure of sedentary activities is essential to fully
understand overall energy expenditure and to better inform
timely, targeted, and pertinent behavioral interventions.
Further investigation is needed to understand the contribution
of sedentary activities of children and youth to overall energy
expenditure and to investigate the possibility of reallocation of
sedentary activities to less sedentary.
References
Ainsworth BE, Haskell WL, Whitt MC, Irwin ML, Swartz AM,
Strath SJ, O’Brien WL, Bassett DR Jr, Schmitz KH, Emplaincourt PO,
Jacobs DR Jr and Leon AS (2000). Med Sci Sports Exerc 32: S498-504
Blair SN, Kohl HW, Gordon NF and Paffenbarger RS Jr (1992).
Annu Rev Public Health 13: 99-126
Bradley CB, McMurray RG, Harrell JS and Deng S (2000). Med Sci
Sports Exerc 32: 2071-8
Brooks-Gunn J, Warren MP, Rosso J and Gargiulo J (1987). Child Dev
58: 829-41
Faith MS, Berman N, Heo M, Pietrobelli A, Gallagher D, Epstein LH,
Eiden MT and Allison DB (2001). Pediatrics 107: 1043-8
Hernandez B, Gortmaker SL, Colditz GA, Peterson KE, Laird NM and
Parra-Cabrera S ( 1999). Int J Obes Relat Metab Disord 23: 845-54
Kimm SY, Glynn NW, Kriska AM, Barton BA, Kronsberg SS, Daniels
SR, Crawford PB, Sabry ZI and Liu K (2002). N Engl J Med
347:709-15
Klesges RC, Shelton ML and Klesges LM (1993). Pediatrics 91: 281-6
Lindquist CH, Reynolds KD and Goran MI (1999). Prev Med 29: 305-12
Marshall SJ, Biddle SJH, Sallis JF, McKenzie TL and Conway TL
(2002). Pediatr Exerc Sci 14: 401-417
McLaughlin JE, King GA, Howley ET, Bassett DR Jr and Ainsworth
BE (2001). Int J Sports Med 22: 280-4
The National Institute of Child Health and Human Development Study
of Early Child Care and Youth Development Network (2003).
Archives of Pediatric and Adolescent Medicine 157: 185-190
Petersen AC, Crockett L, Richards M and Boxer A (1988). Journal of
Youth and Adolescence 17: 117-133
Robinson TN (1999). JAMA 282: 1561-7
World Health Organization: 55th World Health Assembly. (Mar 27,
2002) Diet, physical activity, and health [On-line]. Retrieved May 15,
2003, from http://www.who.int
THE EFFECT OF PLAYGROUND MARKINGS
ON CHILDREN’S PHYSICAL ACTIVITY LEVEL
Stratton Gareth, Mullan E.
REACH Group Liverpool John Moores University, UK
Keywords: physical activity, recess, multi-coloured markings
Few developmentally appropriate and sustainable interventions
aimed at increasing children’s physical activity have been investigated. School recess time represents a setting where children
can engage in daily physical activity for the majority of the year.
The aim of this study was to examine the effect of painting
school playgrounds with multicoloured markings, designed by
children and teachers, on children’s involvement in moderate
and vigorous physical activity (MVPA) during recess.
Four infant (years 4-7) and 4 junior schools (years 7-11) took
part in the intervention. Half served as intervention and the
other half as control schools. Physical activity was measured
using heart rate telemetry with MVPA set at 50% heart rate
reserve. This was repeated over 3 days and 3 recess periods per
child. Of the initial 120 children who took part data from 53
boys (27 infant, 26 junior) and 49 girls (22 infant, 27 Junior)
were available for further analysis.
After mean scores were adjusted for BMI and play duration the
early primary experimental group increased MVPA from
39.6±2.4 to 51.4 ±2.3 compared to a control group decrease
from 39.3±2.5 to 26.1±2.6 % recess time. The late primary
experimental group increased MVPA from 33.2±2.8 to
43.0±3.2 compared to the control group increase from 33.8
±3.5 to 35.5±4.% of recess time. The ANCOVA analysis (time
x age x group) on MVPA revealed a significant 3 way interaction (F 1,194=3.95; p<.01).
Overall, results suggest that multicolor playground markings
can be a low-cost method of significantly increasing children’s
daily physical activity levels in the short term. If these increases could be sustained then playgrounds designed in this way
could make a valuable contribution to physical activity recommendations for young people.
INCREASE IN OBESITY IN CHILDREN FROM 1990 – 2000
Harrell Joanne S1, McMurray Robert G2, Pearce Patricia F1,
Creighton Dana1, Amorim Leila1
1
School of Nursing, 2 Department of Exercise & Sport Science
University of North Carolina at Chapel Hill, Chapel Hill, North
Carolina, USA
Keywords: obesity, race, tracking
Introduction
The recent increase of obesity in children in the US is well-doc-
137
revista
19.9.03
0:50
Página 138
umented. Straus and Pollack (2001), using data from the
National Longitudinal Survey of Youth, showed that between
1986 and 1998, overweight increased significantly in African
American, Hispanic and white children; by 1998, overweight
(BMI > 95th percentile) was 21.5% in AA, 21.8% in Hispanic
and 12.3% in white children. Kimm and colleagues (2000)
demonstrated increasing body mass index (BMI) in a biracial
cohort of 2,379 girls from ages 9 or 10 to ages 18 or 19. BMI
increased in Caucasian and African American girls, but the
prevalence of obesity (> 95th percentile) was twice as high in
African American as in white girls. In the US in 1990, 11%
were overweight and 11.3% were at risk for overweight
(Troiano et al., 1995) while in 2000, 15.3% were overweight
and 15.0% were at risk for overweight (Ogden et al., 2002).
Data from other countries suggest similar increases in obesity
since the 1980’s. Wang, Monteiro and Popkin (2002) showed
that the prevalence of overweight in children nearly tripled
over 15 years in Brazil, doubled in the US from the 1970’s to
1988-1994, and increased by one-fifth in China from 1991 –
1997; however, obesity decreased in Russian children between
1992 and 1998. Data from France, Germany and The
Netherlands indicate that obesity is increasing there also, but
at a slower rate than in the US (Fredriks et al., 2000;Kalies et
al., 2002;Rolland-Cachera et al., 2002).
Recent reviews provide increased evidence supporting the
tracking of obesity (Must and Strauss, 1999;Power et al.,
1997a;Serdula et al., 2001), as do primary studies (Guo and
Chumlea, 1999;Power et al., 1997b;Sugimori et al., 1999;Valdez
et al., 1996;Whitaker et al., 1997). Several studies have demonstrated that childhood obesity is a very significant risk for adult
obesity. The Bogalusa study reported 77% of children with
BMIs greater than or equal to the 95th percentile are still obese
as adults (Freedman et al., 2001). These correlations for
Bogalusa between childhood BMI and adult BMI (r = 0.58) are
also consistent by age, race, and gender (Freedman et al.,
2001). DiPietro and associates (1994) studied 504 obese children (aged 2 months to 16 years) with follow-up every 10
years for 40 years and reported the disturbing finding that all
of these 504 obese children became obese adults. Because of
this high level of tracking of obesity from childhood into adulthood, it is important to more fully understand the prevalence
of obesity in childhood.
We hypothesized that obesity would be highly prevalent in
North Carolina, a racially diverse, highly rural state in the
Southeastern US. The purpose of this study was to compare
the prevalence of obesity in racially mixed samples of 8 to 10
year old children in North Carolina in 1990 and 2000 and to
see if the prevalence of obesity or the rate of increase in obesity
differed by ethnicity.
Sample
Subjects were 3,240 children who were studied at two time
points; 2,162 children aged 8 – 10 were studied in 1990 (77%
white, 19% African American and 4% other races). In 2000 we
examined 1,078 8 – 10 year olds (37% white, 53% African
American, and 10% other races). Data were collected in 48 rural
and urban elementary schools in North Carolina. Children were
excluded from the study if they had a chronic illness such as
diabetes, heart disease, or moderate to severe asthma.
Methods
Trained research assistants collected data in the schools. All
138
study procedures were approved by a multiple assurance
Internal Review Board and Single Project Assurance was
obtained from all school superintendents. Before data collection, parents provided written consent and children signed
assent forms. With participants shoeless, we measured height
in cm with a stadiometer (Perspective Enterprises, Kalamazoo,
MI) and weight in kg with a calibrated balance beam scale
(Detecto Scales. Inc., Brooklyn, NY). Body mass index was calculated (weightkg/heightm2). Three body mass index (BMI) categories were developed using the age and gender tables published by CDC in 2002
(http://www.cdc.gov/nccdphp/dnpa/bmi/bmi-for-age.htm).
Children with a BMI greater than or equal to the 85th percentile and less than the 95th percentile were considered at risk
for overweight and those at or above the 95th percentile for age
and gender were considered overweight. Race and age was
determined by self-report of the subjects.
Results
In 1990, 34.6% of the 8 – 10 year old children were either at
risk for overweight or overweight. By 2000, 47.2% were either
overweight or at risk for overweight, that is, at or above the
85th percentile (see Table 1). The greatest increase was in the
highest category, overweight (> 95th percentile). Because the
majority of the sample in 2000 was African American (AA), we
tested the homogeneity of the race-risk association between
1990 and 2000. In 1990, 38.5% of the AA and 33.4% of the
white children were at or above the 85th percentile, while in
2000, 49.6% of AA and 44.2% of white children were at that
level. Even though we studied a greater proportion of AA in
2000, the odds ratios for race were the same for the two time
points (1990, OR = 1.245; 2000, OR = 1.2410). Thus, the
increase in obesity was similar in both races.
The prevalence of obesity in this mainly rural state in the US
increased markedly in the past 10 years. For the corresponding
years, data for the US show that in 1990, 11% were overweight
and 11.3% were at risk for overweight, for a total of 22.3% of
youth at or above the 85th percentile. In the US in 2000, 15.3%
were overweight and 15.0% were at risk for overweight, so
30.3% were at over above the 85th percentile. Thus, the prevalence of both overweight and risk for overweight in North
Carolina children far exceeded that of American children as a
whole. Comparisons with results from other countries are complicated by the use of a variety of sources for norms as well as
different cut-off points. The study by Rolland-Cachera (2002)
demonstrates how results can vary depending on the reference
used. In 2000 in France, 20.6% percent of children (n = 1582)
aged 7 – 9 were either overweight or obese when using the
CDC standards; when the new international cut-off values of
Cole and colleagues (2000) were used, the prevalence was
18.1%. When using the international cut off points for children
in the Bavarian region of Germany, the prevalence of either
revista
19.9.03
0:50
Página 139
overweight or obesity was 10.3% in 1982 and 15.1% in 1997
(Kalies et al., 2002). Thus, it is apparent that childhood obesity
is much more prevalent in the United States than in Europe.
One could speculate that a reason for the greater prevalence of
obesity in North Carolina may be the fairly high number of
African American youth, since obesity has been shown to be a
greater problem in African Americans, especially African
American girls and women. However, while our data indicate
about 5% more African American than white children were
obese at each time point, the rate of increase did not differ for
white and non-white subjects. These results suggest that the
increase in obesity is likely due to common unhealthy lifestyles
of children rather than racial or genetic factors. Interventions
to prevent and treat obesity in children are urgently needed in
North Carolina and in the US to help combat the epidemic of
obesity in children.
References
Centers for Disease Control (BMI for children and teens). (April
2002) Nutrition and physical activity: BMI for children and teens
[On-line]. Retrieved June 1, 2003, from http://www.cdc.gov/nccdphp/dnpa/bmi/bmi-for-age.htm.
Cole TJ, Bellizzi MC, Flegal KM and Dietz WH (2000). BMJ
320:1240-3
DiPietro L, Mossberg HO and Stunkard AJ (1994). Int J Obes Relat
Metab Disord 18:585-90
Fredriks AM, van Buuren S, Wit JM and Verloove-Vanhorick SP
(2000). Arch Dis Child 82:107-12
Freedman DS, Khan LK, Dietz WH, Srinivasan SR and Berenson GS
(2001). Pediatrics 108:712-8
Guo SS and Chumlea WC (1999). Am J Clin Nutr 70 :145S-148S
Kalies H, Lenz J and von Kries R (2002). Int J Obes Relat Metab
Disord 26:1211-7
Kimm SY, Glynn NW, Kriska AM, Fitzgerald SL, Aaron DJ, Similo
SL, McMahon RP and Barton BA (2000). Med Sci Sports Exerc 32:
1445-54
Must A and Strauss RS (1999). Int J Obes Relat Metab Disord 23
Suppl 2:S2-11.
Ogden CL, Flegal KM, Carroll MD and Johnson CL (2002). JAMA
288:1728-32
Power C, Lake JK and Cole TJ (1997a). Int J Obes Relat Metab
Disord 21:507-26
Power C, Lake JK and Cole TJ (1997b). Am J Clin Nutr 66:1094-101
Rolland-Cachera MF, Castetbon K, Arnault N, Bellisle F, Romano MC,
Lehingue Y, Frelut ML and Hercberg S (2002). Int J Obes Relat Metab
Disord 26:1610-6
Serdula MK, Alexander MP, Scanlon KS and Bowman BA (2001).
Annu Rev Nutr 21:475-98
Strauss RS and Pollack HA (2001). JAMA 286:2845-8
Sugimori H, Yoshida K, Miyakawa M, Izuno T, Takahashi E and
Nanri S (1999). J Pediatr 134:749-54
Troiano RP, Flegal KM, Kuczmarski RJ, Campbell SM and Johnson CL
(1995). Arch Pediatr Adolesc Med 149: 1085-91
Valdez R, Greenlund KJ, Wattigney WA , Bao W and Berenson GS
(1996). Int J Obes Relat Metab Disord 20:715-21
Wang Y, Monteiro C and Popkin BM (2002). Am J Clin Nutr 75:971-7
Whitaker RC, Wright JA, Pepe MS, Seidel KD and Dietz WH (1997).
N Engl J Med 337:869-73
GROWTH TYPE AND MOTOR PERFORMANCE IN OBESE CHILDREN
Zsidegh Miklós, Mészáros János, Mohácsi János,
Uvacsek Martina, Tatár András, Mészáros Zsófia,
Prókai András, Vajda Ildikó
Semmelweis University Budapest, Faculty of Physical Education
and Sport Sciences, Hungary
Keywords: growth type, obesity, endurance
Introduction
A greater than biologically required (normal) ratio of fat gain
in healthy individuals is the consequence of serious imbalance
between energy consumption and utilisation, consequently it is
the result of sedentary lifestyle. The increasing ratio of fatness
and obesity presents a great challenge in all developed and
many of developing countries (Bouchard 2000). The summarised ratio of fat and obese children increased from 22% up
to 28% in Hungary during the past 25 years, as one of the consequences of very characteristic hypoactive lifestyle (Mészáros
et al. 2001). However, no clear agreement exists among the
investigators in the qualification of fatness and obesity. Many
of the paediatricians suggest the BMI over 30 kg × m-2 as one
of the most important criteria (Cole et al. 2000, Viner 2000)
beyond the high ratio of body fat content and waist and hip circumference ratio. Since BMI increases significantly with age
this technique of qualification often results only slight overweight instead of marked fatness or moderate obesity. Another
difficulty with these criteria is that they not only are impossible to compare across populations, but when they are applied
with advancing age, they do not correspond to the criteria for
classification of overweight based on BMI for adults. Currently,
a subgroup of the WHO International Obesity Task Force
(IOTF) is attempting to develop international BMI-by-age standards. The opinion of Lohman (1992) in this respect is more
simple and more useful. The boys and adolescents with relative
body fat content between 25-30% must be evaluated as fat, and
over 30% of relative body fat content the obesity starts irrespective of the method of estimation. Since the long lasting fatness or obesity is a risk factor of numerous diseases, the prevention of obesity should be among the high priorities in public health. This prevention should certainly include encouraging
healthy lifestyle in all age groups including children and adolescents. This cannot be achieved by efforts aimed at the individual level. Communities, governments, the media, and the
food industry need to work together to modify the environment so that is less conductive to weight gain (WHO 1998).
The question arises more and more often: Is the obesity illness
or it ”just” the anteroom of various disorders.
The aim of the present study was to analyse the morphological
properties and physical performance characteristics of definitely obese school-boys.
Methods
A total of 2152 volunteer Hungarian children aged between
10.51 and 13.50 years were investigated in the years of 2001
and 2002. Among them 455 were qualified as obese. Obesity
was classified by the BMI (mean + 2SDs in all the four age
groups) and a relative body fat content (greater than 30%). The
body fat content relative to body mass was estimated by the
suggestions of Parízková (1961). This technique requires 10
139
revista
19.9.03
0:50
Página 140
skinfold thickness measurements. The physique was described
by the growth type indices introduced by Conrad (1963). The
metric index is the ratio of chest depth and chest width corrected by the height. The index characterises the linearity (or
roundness) of physique between the leptomorphic and picnomorphic extremes. The plastic index is the sum of shoulder
width, lower arm girth and hand circumference, and it is the
absolute estimation of bone-muscle development of the growth
type. The plastic index has significant correlation with simple
motor test scores and the bone age in non-fat and non-obese
children and adolescents (Mészáros et al. 1986). Since the
growth type technique uses neither skinfold thicknesses nor
body mass for the description of physique, the comparison of
growth type indices should be more informative in this respect
than the anthropometric somatotyping as for instance.
The physical performance capacity was estimated by the results
in 30 m dash, standing long jump, fist ball throw and 1200 m
run. All the used motor test items are the part of 8-grade general school physical education program. The best results of the
attempts in the speed and co-ordination tests were analysed.
Differences between the age group means were analysed by Ftest following one-way ANOVA.
Results
The results of descriptive and comparative statistics for anthropometric variables of non-fat (body fat content is below 25%)
and obese boys are summarised in Table 1. The obese children
and adolescents were significantly taller, than the non-fat boys,
and their growth type was remarkably picnomorphic and hiperplastic in this comparison. Nevertheless, the mean heights in
both groups of our investigations were slightly taller than their
age mates in the representative Hungarian sample (Eiben et al.
1991). This results can be explained with the effects of secular
growth trend (the representative data collection was carried out
12 years earlier), but does not inform about the possible reasons of the consistent height differences of the obese and nonobese children The taller height of fat and obese youngsters
were also published following the investigation of smaller samples of Hungarian children adolescents in both sexes (Frenkl et
al. 1988, Mészáros et al. 1989). The extremely high body mass
and BMI means with significant age dependency are obviously
the consequence of grouping. Nevertheless the obese children
were heavier than their non obese counterparts by more than
17.4-22.6 kg. The relative body fat content means were greater
by 12-13% than the respective Hungarian age group averages at
the end of the century (Mészáros et al. 2001) and by 15% higher than the means 13 years ago (Szmodis et al 1990).
Mean differences between the motor performance scores can be
seen in Figure 1-4. The full lines and the dots refer to the
respective mean trends (linear regression lines) in the group of
non-fat boys. The circles indicate the mean scores of the obese
children. The vertical lines are the 0.5 standard deviations. The
obese children and adolescents performed in very low level.
The differences between the group means (non-fat and obese)
were significant in all four age groups and all four motor tests,
in spite that the mean performances of non-obese children
were also moderate, significantly lower, than those in the
Budapest investigation of Szabó (1977). The relative standard
deviations (SD × 0.01mean-1) were the highest around the
1200 m run scores, and the lowest in 30 m dash. Although the
age dependency was significant in all four performances in the
groups of non-fat and non-obese children, no statistical differences were found between the group means of obese boys.
140
Table 1: Means and standard deviation of anthropometric variables
Abbreviations: SD = standard deviation, F% = relative body fat
content, * = difference between the means is significant
at 5% level of random error.
Figure 1. 30 m dash
Figure 3. Fist ball throw.
Figure 2. Standing long jump.
Figure 4. 1200 m run.
The mean performances of obese boys in 30 m dash were lower
by ”only” 10-13%, in standing long jump 22-23%, in fist ball
throw 27-19% and in 1200 m run 29-38% than those of the
children with normal body fat content.
Discussion
The very moderate motor performances of the obese children
and adolescents should be evaluated as consequences of
extremely high body fat content and the lifestyle which resulted in the observed unfavourable body composition through the
past years. Laki and Nyerges (2000) has stressed that less than
10% of the respective population can be evaluated as athletic at
the end of the past millennium, in contrast to the more than
35% in the middle of seventies. Moreover more than 50% of
the Hungarian children evaluate a monthly excursion as regular
physical activity.
Using Szabó’s (1977) 0-15 scoring system (in which the maxi-
revista
19.9.03
0:50
Página 141
mum score is 60) the level of physical performance capabilities
was more or less balanced in the group of non-fat children,
they reached 28-32 points. The obese children have performed
better in short burst activities and their scores were very close
to zero in 1200 m run. Their summarised mean scores were
consistently below 12 points!
Although the relationship between body fat content or BMI and
the level of cardiorespiratory fitness is obviously strong, the
physical performance capacity of an obese but athletic children
can often reach the average or exceeds it remarkably. There is
evidence from several studies that physical activity appears to
protect against chronic disease morbidity and mortality in fat
and obese children and adolescents (Bouchard 2000). The
determination of the optimal exercise dose for body composition is of primary importance. Relatively little is known about
how much, what modality, or what intensity of aerobic exercise
is most efficacious in altering cardiorespiratory fitness. In concerning the relationship of regular exercise and cardiorespiratory fitness in youths, it is necessary to note that many of the
exercises pose some risks in the form of sport injuries.
The physique of fat or especially obese children, adolescents,
and adult individuals are described as balanced endomorph or
meso-endomorph by using the anthropometric somatotyping
method for the determination (Carter and Heath 1990).
However, it cannot be forgotten, that in calculating somatotype
components as well as in the simple indicators of fatness and
obesity (for instance: BMI, ponderal index, relative body mass
etc.) the skinfold thicknesses directly or the body fat content
(as a part of body mass) inclusively are the variables for the
estimation. One of our observations have the following
stressed methodological importance too. The metric index as
being directly independent of skinfold thicknesses and total
body mass, sensitively points out the differences among the
morphological physiques. The question of the relationship
between the skinfold thicknesses around the chest and the
measurable diameters may arise naturally. Using special chest
calliper in taking the dimensions, the distorting effect of various skinfold thicknesses is negligible in our opinion. The metric indices in the groups of obese boys were greater by 53-60%
than in the non-obese. Since the marked differences in the
individual or mean metric indices are independent of skinfold
thicknesses, it cannot be excluded that the observed metric
index variability refers to the inherited characteristics of
physique. Though Kretschmer has already stressed by theoretical considerations that the picnic constitution is more sensitive
for fat gaining than the leptosom, and Bouchard (2000)
described metabolic differences between the extremes of
physique, these results do not give exemption for the fat and
obese individuals. Nevertheless, the sensitivity alone does not
mean necessity.
Some opened questions remained in the possible explanations
of consistently taller stature of obese children and adolescents.
Frenkl and associates (1988) pointed out the effects of earlier
biological maturation. Since the height differences of obese and
non-obese 17-18-year-old boys and young adult males are non
significant generally, this effect cannot be excluded, but it is
difficult to understand if the obesity is serious risk factor for
various serious diseases, how this unfavourable biological state
can facilitate the peed of growth and biological maturation.
In summary. The ratio of obese children among the 10-13-yearold Hungarian boys is very high. As a consequence of definite
hypoacticity for the greater than 30% body fat content refers
very low level of cardiorespiratory endurance. Since the normal
child development and school physical education cannot compensate the strong effects of the environment the challenge is
enormous. The various treatment modalities of the obesity are
characterised by only modest success, and the measurable
weight loss is followed by similar weight (fat) regain is often
reported, consequently the only suggestion is to prevent the
development of fatness and obesity among the growing children. It will require massive resources and an unprecendent
level of concentration among all public health agencies and private organisations to begin reversing the trend that have
emerged over the past decades.
Acknowledgement
The authors express their gratitude to the Hungarian Society of
Sport Science for the financial support of this investigation.
References
Bouchard C (2000). Physical Activity and Obesity. Human Kinetics,
Champaign, Illinois
Carter JEL, Heath BH (1990). Somatotyping development and applications. Cambridge University Press, Cambridge, New York, Port
Chester, Melbourne, Sydney
Cole TJ, Bellizzi MC, Flegal KM, Dietz WH (2000). British Medical
Journal, 320: 1240-1243
Conrad K (1963). Der Konstitutionstypus. Springer Verlag, Berlin
Frenkl R, Mészáros J, Mohácsi J, Bukta M (1988). Young athletes;
biological, physiological, and educational perspectives. Human Kinetics
Publishers, Inc., Champaign, Illinois, 93-97
Eiben OG, Barabás A, Pantó E (1991). Humanbiologia
Budapestinensis, 21: 123
Laki L, Nyerges M (2000). Kalokagathia, 75th Anniversary, Special
Issue, 24-35
Lohman T (1992). Advances in Body Composition Assessment.
Human Kinetics Publishers, Inc., Champaign, Illinois
Mészáros J, Mohácsi J, Frenkl R, Szabó T, Szmodis I (1986). Children
and Exercise XII. Human Kinetics Publishers, Inc., Champaign,
Illinois, 347-353
Mészáros J, Mohácsi J, Farkas A, Frenkl R (1989). Children and exercise XIII. Human Kinetics Publishers, Inc., Champaign, Illinois, 75-80
Mészáros J, Othman M, Szabó T (2001). The exchange and development
of sport culture in east and west. NTNU-AIESEP, Taipei, 102-103
Parízková J (1961). Metabolism, 10: 794-807
Szabó T (1977). Utánpótlás-nevelés, 3: 1-53
Szmodis M, Mészáros J, Mohácsi J (1990). FIMS World Congress of
Sports Medicine, Abstracts, Amsterdam, 199
Viner R (2000). British Medical Journal, 320: 1401
Weiner JES, Lourie JA (Eds.)(1969). Human Biology. A Guide to
Oxford
WHO (1998). Obesity: preventing and managing the global epidemic.
WHO, Geneva WHO/NUT/NCD/98.1
EUROFIT TEST RESULTS IN PRIMARY SCHOOL CHILDREN:
A COMPARISON
Taylor Suzan R, Stratton Gareth, Hackett Allan F,
Lamb Elizabeth
RISES, Liverpool John Moores University, UK
141
revista
19.9.03
0:50
Página 142
Keywords: Eurofit, primary school children, normative data
The aim of this study was to assess the health and skill related
fitness of children from Liverpool (UK) and compare the findings to those reported in the literature. Currently there are no
published studies on English children of primary school age. A
total of 719 children (413 boys and 306 girls) performed a
series of tests based on the Eurofit Tests of Physical Fitness
(1988). The participants were all in year 5 (aged 9-10y). The
following tests were performed after a short warm-up: 10 x 5
shuttle run, plate tapping, speed bounce, sit and reach, standing broad jump (SBJ), modified pull-ups, grip strength (GS),
and the 20m shuttle run (20-MST). Stature, body mass, triceps
skinfold and subscapular skinfold were also measured. The
results of this study demonstrate that compared with children
in Northern Ireland (Mahoney et al., 1991) Liverpool boys
were 3% taller, 10% heavier, and 6% stronger (GS). A similar
trend was evident in the girls who were 3% taller, 14% heavier
and 9% stronger. However, the Eurofit tests showed that the
children of Liverpool scored below average on many of the
health and skill related tests. The only exceptions to this were
the 20-MST and the SBJ, where both the groups of boys performed 46 laps and jumped a distance of 132 cm. Results from
the 10 x 5 m shuttle run showed that the speed and agility of
the children from Liverpool was ~9% slower than those
recorded in Belfast. Furthermore, the endurance test showed a
9.5% difference between the girls’ data, with 33 laps compare
to 36 laps for the children from Liverpool and Belfast respectively. The sit and reach test highlighted the poor flexibility of
the children from Liverpool. Further comparisons with other
European countries are difficult to make due to the lack of
reported studies using the Eurofit tests on primary school children. However comparisons with a study conducted in America
shows that the upper body strength of the children from
Liverpool was 44% (boys) and 63% (girls) of their American
counterparts (Ross et al., 1987). In conclusion the results of
the present study demonstrate that the children of Liverpool
have a below average performance on some of Eurofit tests
when compared to children of the same age in different countries. These fitness issues may have implications for the future
health of the people of Liverpool. An intervention strategy is
being implemented to encourage participation in sport and
physical activity among school children.
tion are not available. Though it is not possible to go back in
time, some cultures (Old Order Mennonites, Amish) have preserved the inherently active lifestyle of earlier generations,
before technology seriously eroded leisure-time physical activity, and before the childhood obesity epidemic. As a means of
assessing whether the physical fitness of Canadian children has
deteriorated concomitant with changes in lifestyle behaviour
observed over the past few generations this study compared
the fitness level of children living a traditional lifestyle with
those living a contemporary Canadian lifestyle.
Methods
The health-related physical fitness of 399 9-12 year-old children (“tweens”) was assessed in this study. The fitness of 124
Old Order Mennonite children (OOM) was compared to both
rural (n=165) and urban (n=110) dwelling children. The
Mennonites live a traditional rural lifestyle without the modern
conveniences of contemporary living (e.g. no motorized vehicles, TV, radio, computers, video games, organized sport). The
rural and urban children live a contemporary Canadian
lifestyle. Fitness was measured using the Canadian Physical
Activity, Fitness, and Lifestyle Appraisal (CPAFLA). The
CPAFLA is a battery of tests measuring anthropometry (height,
weight, skinfolds, waist girth), aerobic fitness (step test), and
musculoskeletal fitness (grip strength, push-ups, curl-ups, sitand-reach flexibility). Sitting height was also obtained to allow
a calculation of maturational age using the procedures of
Mirwald et al. (2002). Using maturational age as a covariate
ANCOVA was used to assess differences in fitness between the
three groups (OOM, rural, urban).
Results
A summary of the group fitness data using adjusted means
(standard error) is reported in Table 1. OOM showed significantly greater grip strength than both the urban and rural children (p<0.0001) and significantly better aerobic fitness than
the rural group (p<0.0001). No differences in BMI were
observed, but the triceps skinfolds were significantly smaller in
the OOM children (p<0.05). No differences in curl-ups were
observed between the groups. Push-ups and flexibility measures were significantly lower (p<0.01) in the OOM group.
Table 1: Summary fitness data comparing OOM children
with rural and urban Canadian children.
FITNESS LEVEL OF CHILDREN LIVING TRADITIONAL
VS CONTEMPORARY LIFESTYLES
Tremblay Mark S, Barnes Joel D, Esliger Dale W,
Copeland Jennifer L
College of Kinesiology, University of Saskatchewan,
Saskatoon, Canada
Keywords: fitness, lifestyle, contemporary living
Introduction
Reductions in lifestyle physical activity and increases in childhood obesity have caused speculation that the fitness level of
Canadian children has declined over the past few generations.
Unfortunately, accurate data to effectively assess this specula-
142
Collectively, the results suggest that children who live a
lifestyle somewhat representative of previous generations
(OOM) are leaner, stronger and more aerobically fit than children living a contemporary Canadian lifestyle. The superior fitness of the OOM may be caused by their lifestyle-related physical activity (e.g. farm chores, active commuting). It is possible
that the lack of institutionalised physical education in the
Mennonite school system contributed to their unfamiliarity
with the push-up test. Therefore, the apparent contradiction
between grip strength results and push up results may be
revista
19.9.03
0:50
Página 143
attributed to a learning effect. Additionally, the apparent poor
flexibility scores of the OOM on the sit-and-reach test may be
explained in part by their tight/restrictive clothing. This study
provides insight into the speculation that the health-related
physical fitness of contemporary Canadian children has
declined over the last few decades and may offer an explanation to the rising obesity epidemic.
This research was supported by the Canadian Population
Health Initiative of the Canadian Institute for Health
Information.
References
Mirwald RL, Baxter-Jones ADG, Bailey DA, Beunen GP (2002). Med.
Sci. Sports Exerc. 13: 6 89-694
PROMOTING INFORMAL PHYSICAL ACTIVITY AT SCHOOL RECESS.
A PILOT STUDY WITH GIRLS AND BOYS FROM 2nd AND 4TH GRADES
OF ELEMENTARY SCHOOL
Afonso Bela, Botelho Gomes Paula
and constructions. Once again boys and girls were monitored
on 3 recess periods.
Continuing duration record was applied to collect data.
Data analysis was done using the following statistical techniques: descriptive measures and Wilcoxon non parametric test
in order to find out about physical activity changes between
Moment 1 and 2, in each sex.
An alpha level of 0.05 was used to determine significance.
Results
According to results from Moment 1 physical activity was
defined by motor skills such as walk, run, jump, balance, by
activities such as play chase, play fight, skipping rope, hopscotch, and by simplified ball games (e.g. soccer). Inactivity
was defined by behaviors such as to be seated, chatting, playing
with electronic toys).
Results for girls
Table 1 and 2 show results concerning activity/inactivity for
girls from 2nd grade in Moment 1 (M1) and 2 (M2).
Table 1: Girls, 2nd grade (n=8) – Total time Activity / Inactivity,
mean and standard deviation in M1 and M2 (hours:minutes:seconds)
Keywords: physical activity, recess, girls, boys
Introduction
Urbanization, non-traditional family structures, proliferation of
technological games, the increasing schooling of free time and
the poorness of motor stimulation are clearly pointed out in
the literature as being barriers to informal physical activities,
free play and children socialization (Neto, 1999; 2001).
On the other hand is asked to school to promote physical activity, but results from several studies all over the world seem to
find out that school can’t surpass the situation, and that girls
have always less amounts of physical activity than boys
(Pomar&Neto, 1997). If physical activity at school is important
for all, this importance is higher to girls.
It’s unbelievable that children don’t like anymore to play, run
and jump. We think that school doesn’t what it should be
done; we propose simple changes to promote informal and free
physical activity at school recess time.
The main goal of this study was to analyze children’s physical
activity at recess in an open space without materials (Moment
1 of the study) and their behavior when unfixed and unstereotyped materials were introduced (Moment 2).
Methods
Data for this study were collected from 16 girls and 16 boys
from 2nd and 4th grades of elementary school.
Moment 1 (diagnosis) monitored 3 recess periods in order to
find out favorite plays and motor skills, and the amount (in
time) of physical activity. Categories a posteriori (activity/inactivity) were created based on these first results. According to
their preferences and the literature (Botelho Gomes, 2000), we
proposed a rearrangement of how space was occupied and
introduced the materials for free play (ropes; hula-hoops; tennis balls; balls from different dimensions; sets for field hockey;
junior and senior stilts; elastic bands; hoops; blocks for balance
The amounts of time for activity / inactivity in M1 are alike. But,
in M2, when girls had the opportunity to explore new materials
and conquest more space for play, the value for activity almost
duplicated, and, of course, inactivity time suffered a decrease of
about 34% (approximately 3 hours). In the present study, total
time for activity in M1 is similar to that one found by Sleap and
Warburton (1992). However, these authors were interested on
intensity of physical activity, which wasn’t our case.
Observing table 2 we can say that 7 girls were physically more
actives in M2, and that fact means that occurred statistically
significant differences intra-group.
In other hand, all the girls were less inactive in M2 than in M1
(z=0.012;p≤0.05).
This kind of results allow us to affirm that recesses can became
an import moment for physical activity if the space and materials (simple and cheap) put some challenge and promote informal and free play.
Table 2: Girls 2nd grade (n=8) - results from M1 vs. M2
(Difference value, Mean Rank and Z value)
Legend: a. activity M2<activity M1; b. activity M2>activity M1;
c. inactivity M2=inactivity M1; d. inactivity M2<inactivity M1;
e. inactivity M2>inactivity M1; f. inactivity M2=inactivity M1
* p ≤ 0.05
143
revista
19.9.03
0:50
Página 144
Table 3 and 4 show the results for girls from the 4th grade.
Table 3: Girls, 4th grade (n=8) – Total time Activity / Inactivity,
changed behaviors in both variables: 8 positive differences in
activity and 8 negative differences in inactivity, with a Z value
that is statiscally significant.
Table 6: Boys 2nd grade (n=8) - results from M1 vs. M2
In M1, time spent in inactivity is higher than that one to activity (about 62% from total time for recess). Mota & Rodrigues
(1999), studying Portuguese children, also refer that children
have low participation in free activities.
Analyzing values for M2 we can see that total time in activity is
more than the double than in M1, and the inactivity decreased
almost 4 hours. In the first set of recess periods (3) the mean’s
value found for inactivity is almost 45 minutes, but in M2
decreased to 15 minutes and a half. For these girls, the materials and facilities in M2 promoted a revolution in recess!
Table 4: Girls 4th grade (n=8) - results from M1 vs. M2
* p ≤ 0.05
Comparing the values in both moments of the study, we can
verify that for activity there are positive differences in all the
girls from 4th grade; that means that they were significantly
more actives in M2 (Mean Rank = 4.50; Z= 0.012, p ≤0.05).
* p ≤ 0.05
Table 7 and 8 show the results for boys from the 4th grade.
Table 7: Boys, 4th grade (n=8) – Total time Activity / Inactivity, mean
and standard deviation in M1 and M2 (hours:minutes: seconds)
Boys from 4th grade are the most actives in M1. Nevertheless
they became even more actives in M2: 8 positive differences in
activity and 8 negative differences in inactivity, with a Z value
that is statiscally significant (table 8). Amazing is the value for
inactivity in M2: 0:16:53, the lowest value of the present study.
Once again, it seams that the improvements in facilities
reached also this group.
Table 8: Boys, 4th grade (n=8) - results from M1 vs. M2
Results for boys
Table 5 and 6 show the results for boys from the 2nd grade.
Table 5: Boys, 2nd grade (n=8) – Total time Activity / Inactivity,
* p ≤ 0.05
In the first set of observations (M1, diagnosis), we can see that
if boys were physically active a little bit more than 5 hours, and
the time spent in inactivity is something terrifying: almost 4
hours and a half. Perhaps the routine and an empty space
couldn’t motivate them to play and actively enjoy the free time.
The little transformation of the recess period allowed, in M2,
to promote another attitude about physical activity: more than
8 hours in total time, with a mean of 1 hour and 7 minutes!
The total time of inactivity decreased considerably (more than
3 hours).
The results from Wilcoxon test (table 6) prove that all boys
144
Conclusions
The pedagogical intervention in order to improve physical
activity in recess periods, through simple changes, surpassed
everything what we could expect. 15 girls and all the boys (16),
independently of the scholar grade, got a significant increased
in time spent in physical activity.
Little things can make big differences.
References
Botelho Gomes P (2000). Educação Física no 1º ciclo: 54-61
Mota J, Rodrigues S (1999). Jogo e espaços lúdicos infantis.
Neto C (1999). A criança a escola e a educação física: 9-18
revista
19.9.03
0:50
Página 145
Neto C (2001). Aprendizagem motora – problemas e contextos: 193-220
Pomar C, Neto C (1997). Jogo e desenvolvimento da criança: 178-205
Sleap M., Warburton P (1992). RQES 63 (3): 238-245
MOTOR COORDINATION LEVEL OF CHILDREN (6-10) OF THE
AZORES ISLANDS
Lopes Vitor P1, Maia José AR2, Morais Francisco P2,
Seabra André2, Silva Rui G2
1
School of Education, Polytechnic Institute of Bragança, Portugal
2
Keywords: motor coordination, children, development
The purposes of this study were: (1) to characterize the level of
motor coordination (MC) development in children (6 to 10
years), and (2) to analyse gender differences. Sample size comprises 3742 children (boys n=1829; girls n=1913) with 6 to 10
years of age. Motor coordination was evaluated according to the
body coordination test battery (KörperkoordinationsTest für
Kinder) developed by Kiphard e Schilling (1974). The battery
comprises four tests: backward balance (BB), jumping sideways
(JS), hopping on one leg (HL), and shifting platforms (SP).
Factorial ANOVA (gender*age) was used to identify differences
between boys and girls in each age. Discriminant function was
used to test differences among multivariate profiles of motor
coordination and was used to classify the children in each age
group. All analysis were done in SPSS 10.0. It was found that
performance increased with age in both gender, and in all coordination items. Boys out perform girls except in JS.
The first discriminant function explains 98.3% of generalized
variance in boys (lambda = 0.617; Rc = 0.61), and 98% in
girls (lambda = 0.635; Rc = 0.60). In both gender, the reclassification in each age group, was of low percentage (36.3% for
boys and 34.5% for girls. We found a high number of children
that had a lower multivariate profile of MC than the one
expected for their age. It was also found that a high number of
children had a higher multivariate profile of MC than the one
expected for their age.
Conclusions: (1) the level of motor coordination was higher in
older age groups, (2) boys had superior level of coordination
than girls; (3) and there was low percentage of children with a
coordination level correspondent with their own age; (4) and
also a substantial number of children with a lower profile than
the one expected for their age.
RELATIONSHIP BETWEEN TECHNICAL SKILLS
AND GAME PERFORMANCE IN YOUTH BASKETBALL PLAYERS
Brandão Eurico, Janeira Manuel, Cura João, Cura Pedro
Introduction
In spite of the multidimensionality of sports performance,
Technical Abilities (TA) assumes an important role in the athletes’ competitive capacity (Inglis, 1980; Riezebos et al., 1983;
Beard, 1991; Maia, 1993; Janeira, 1994; Brandão, 1995;
Sampaio, 2000).
The reasons of this importance root in two fundamental
aspects: first, because represents a decisive factor in the youth
athletes, allowing the best performers to present better
incomes in game situation (Araújo, 1992; Thomas, 1994; Riera,
1995; Brandão et al., 1998; Adelino, 2000); second, because
more endowed athletes from a technical point of view can
reach in the future better sport results (Hopkins 1977, 1979;
Brooks and col., 1987; Janeira, 1988; Brandão, 1995; Neta,
1999; Oliveira, 2000; Rocha, 2000; Silva, 2000; Trapani, 2000).
In this domain, analytical technical evaluation has been developed through Testing Batteries (TB) and the Technical Circuits
(TC), although, this kind of technical evaluation goes away
from the more actual perspectives, which refers that qualitative
assessment is always a better way to look for game’s reality
(Griffin et al., 1997; Janeira, 1998; Oslin et al., 1998).
Commonly, athletes’ game performance evaluation is made
through game statistics. Starting from this game statistics it is
possible to define player’s effectiveness coefficients, which are
good indicators of players’ global performance in competition
(Sampaio, 2000).
On the other hand, it is also available in the literature another
instrument to evaluate qualitatively the players’ technical performance in competition - The Game Performance Assessment
Instrument (GPAI) - proposed by Oslin et al. (1998).
This idea was already studied in Basketball senior athletes
(Rowe & Boutmans, 1997), but still unknown for young players. Therefore, the aim of this study was to identify the degree
of relationship between technical skills and technical game performance in youth basketball players.
Method
The sample comprises 70 male basketball players aged from 12
to 14 years old, from 7 teams of Aveiro Basketball Association.
Offensive technical skills (Passing, Dribbling and Shooting)
were evaluated according to AAPHERD Basketball Battery
(Kirkendall et al., 1987) and a Technical Circuit proposed by
Brandão et al., (1998). Qualitative offensive technical game
performance was evaluated according Game Performance
Assessment Instrument – (GPAI - Game Performance), proposed by Oslin et al. (1998) and quantative offensive technical
game performance was evaluated according Game Statistics –
(MVP). Pearson Correlation and Simple and Multiple
Regression were used as data analysis techniques.
Main results and discussion
Table 1 shows Simple Linear Correlation and Regression values
between variables.
Table 1. Simple Regression between Technical Circuit
and game performance (GPAI and MVP)
Faculty of Sport Science and Physical Education,
Keywords: basketball, performance, technical skills
145
revista
19.9.03
0:50
Página 146
These results evidence a moderate association between
Technical Circuit and game performance (GPAI: r=0,69; MVP:
r=0,65). Common variance was 48% and 42%, respectively.
Figure 1 and Figure 2 expresses the regression lines for qualitative and quantitative association between game performance
and Technical Circuit.
Figure 1. Relationship between
GPAI (performance)
and Technical Circuit.
Figure 2. Relationship between
MVP and Technical Circuit.
The associations presented in the previous graphs are positive
and suggest that generally best game performances corresponds to the best results in technical analytical evaluation. For
both regression lines the points’ dispersion is very similar with
values of SEE of 2,83 and 2,80, respectively.
Table 2 presents Multiple Regression analysis for the offensive
tests of AAHPERD Basketball Battery and the game technical
performance (GPAI and MVP).
Table 2. Multiple Regressions between AAPHERD Basketball
Battery and game performance (GPAI and MVP)
(*) GPAI (performance); (**) MVP
These results show the contribution of Shooting in the explanation of game performance (GPAI: Coef ß=0,35; MVP: Coef
ß=0,18), confirming the importance this skill in Basketball game,
when appreciated in quantitative and qualitative perspectives. In
fact, Shooting relevance in Basketball performance is largely
described in the literature (i.e. Marques, 1990; Inglis, 1980; Lidor
& Arnon, 1997; Neta, 1999; Sampaio & Janeira, 1998).
On the other hand, GPAI and MVP variation is explained in 61%
and 57%, respectively, by technical indicators associated variation, analytically studied. Similar values were identified by Neta
(1999) between technique and youth teams final standings.
However, Rowe and Boutmans (1997) concluded that, at high
level competition (senior players), technique is low correlated
with players’ performance (r=0,17).
Contrasting these results, it is clear that technique is quite
important for youth players’ performance, losing importance
along players’ sports career.
The explanation of this matter seems us extremely fascinating.
The possibility of studying youth players longitudinally from a
technical point of view, will help us to better understand this
subject and find more solid justifications concerning technique
146
importance in basketball players’ performance.
In conclusion, AAHPERD Basketball Battery showed a better
association with game performance, in qualitative (GPAI) and
quantitative (MVP) analysis. This result presents the AAHPERD Basketball Battery as the best game performance predictor in this age group and well adjusted for pre-selection proposes of youth basketball players.
References
Adelino, J. (2000). O Treino da Técnica nos Jogos Desportivos In J.
Garganta (ed.), Horizontes e Órbitas no Treino dos Jogos Desportivos.
Centro de Estudos dos Jogos Desportivos - FCDEF-UP, Porto , 91-110
Araújo, J. (1992). Basquetebol: Preparação Técnica e Táctica.
Federação Portuguesa de Basquetebol e Associações Regionais de
Basquetebol, Lisboa
Brandão, E. (1995). A Performance em Basquetebol: Um estudo multivariado no escalão de cadetes masculinos. Master thesis, FCDEF-UP,
Porto (not published)
Brandão, E.; Tavares, F.; Alves, R. (1998). Revista Treino Desportivo,
(4): 13-16
Brooks, M. A.; Boleach, L. W.; Mayhew, J. L. (1987). Perceptual and
Motor Skills, (64): 823-827
Griffin, L. L.; Oslin, J. L.; Mitchell, S. A. (1997). Teaching Sport
Concepts and Skills: A Tactical Games Approach. Human Kinetics
Publishers, Inc. Champaign, Illinois.
Hopkins, D. R. (1977). The Research Quarterly (3): 535-540.
Hopkins, D. R. (1979). The Research Quarterly (3): 381-387
Janeira, M. A. (1998). Abstract Book of the IV World Congress of
Notational Analysis of Sport, FCDEF-UP, Porto, 24
Kirkendall, D. R.; Gruber, J. J.; Johnson, R. E. (1987). Measurement
and Evaluation for Physical Educators. Human Kinetics Publishers,
Inc. Champaign, Illinois.
Neta, P. (1999) - As Habilidades Técnicas e a Performance em Jovens
Basquetebolistas: um estudo no escalão de iniciados masculinos.
Monograph, FCDEF-UP, Porto, (not published)
Oliveira, A. (2000). Habilidades Técnicas e a Performance de
Basquetebolistas: um estudo realizado no escalão de iniciados femininos. Monograph, FCDEF-UP, Porto, (not published)
Oslin, J. L.; Mitchell, S. A ; Griffin, L. L. (1998). Journal of
Teaching in Physical Education,, (17): 231-243
Riera, J. R. (1995). APUNTS - Educación Física y Deportes., (39):
45-56
Rocha, F. J. (2000). A influência dos anos de prática no nível de execução
das Habilidades Técnicas em Basquetebol: um estudo no escalão de iniciados masculinos. monograph, FCDEF-UP, Porto, (not published)
Rowe, P. J.; Boutmans, J. (1997). A Statistically Based Model for
Individual Performance Assessment (IPA) in Basketball. Departement of
Sport and Movement Science, Katholieke Universiteit Leuven, Belgium.
Sampaio, A. J (2000). O Poder Discriminatório das Estatísticas do
Jogo de Basquetebol: Novos Caminhos Metodológicos de Análise, Ph,D
Thesis, UTAD, Vila-Real
Silva, R. (2000). As Habilidades Técnicas e a Selecção de Jogadores
em Basquetebol: um estudo no escalão de iniciados masculinos. monograph, FCDEF-UP, Porto, (not published)
Thomas, K. T. (1994). Quest (46): 199-210
Trapani, C. (2000). Keys to Evaluating Youth Players: The Player
Progress Report. [On-line], http://www.bbhighway.com/talk/Coaching
Box/clinics.
revista
19.9.03
0:50
Página 147
RELATIONSHIPS BETWEEN PHYSICAL ACTIVITY, PERCEIVED
MOTOR ABILITIES AND OPINIONS ABOUT SCHOOL PHYSICAL
EDUCATION IN 16-18 YEAR-OLD ADOLESCENT
Jürimäe Toivo, Pedaste Jaan
University of Tartu, Estonia
Keywords: physical activity, perceived motor abilities, school physical
education
The aim of this study was to investigate the relationships
between physical activity level, perceived fitness and the level
of school physical education lessons in 16-18 year-old adolescents. In total, 858 16-18 year old adolescents (335 males and
523 females) from Tartu, Estonia, were studied. All participants had two obligatory PE lessons every week. Physical activity index (PAI) was calculated according to Telama et al. (1996)
questionnaire. Self-perceived fitness (SPF) was assessed using
questions about perceived strength, speed and flexibility
(Likert type scales). There were five questions about the
changes during last year: changes in school PE lessons, about
the total physical activity and about changes on flexibility,
endurance and strength. Nine questions were connected with
compulsory PE lessons: positive emotions, positive impressions, positive encouragements, etc. The mean PAI indices in
males and females were 9.49±1.94 and 8.96±1.66 (p<0.05),
respectively. Females had more positive emotions and impressions and they liked more PE lessons compared to males. By
the females’ opinion, the PE lessons were quite intensive and
they liked more group work compared to males. During the
last year by the females opinion they had more positive
changes in school PE, their perceived flexibility, endurance and
strength compared to males. Regression analysis indicated that
the PAI characterized 12% (R2x100) in males and 9% in
females of the total variance of perceived motor abilities. The
parameters that characterized the school PE lessons influenced
PAI by 28% and 24 % in males and females, respectively.
Perceived changes in last year characterized PAI by 17% and
6% in males and females, respectively. It was concluded that
physical activity level in males compared with females is more
related to the perceived fitness and opinions about the school
PE lessons level.
PHYSICAL ACTIVITY LEVELS IN CHILDHOOD AND ADOLESCENCE.
AGE AND GENDER DIFFERENCES.
Lopes Vítor P1, Vasques Catarina1, Ferreira João CV2,
Maia José AR3
1
2
3
School of Education, Polytechnic Institute of Viseu, Portugal
Faculty of Sport Science, University of Porto, Portugal
Keywords: physical activity, children, adolescent, accelerometry
Introduction
There is a strong agreement that physical activity (PA) positively influences individual health status. Regular PA is an
important factor along the whole life cycle to promote a
healthy life style. In childhood and youth, the main effects of
physical activity are on the promotion of habits and attitudes
that are thought to be carried out through the adult stage. In
adulthood the benefits are of several levels, as documented in
different epidemiological papers. PA is associated a) to longevity increase; b) to a lower risks of cardiovascular diseases and c)
to the decreases of some of risk factors that are associated with
cardiovascular diseases, such as obesity and hypertension
(Blair, 1993; Mackelvie et al., 2001; Vuori, 2001; Williams,
2001; Riechamn et al., 2002; Westerterp, 1997).
Childhood and adolescence are golden ages to promote and
acquire PA habits. Physical activity promotion in childhood and
adolescence is based in part on the assumption that PA habits
are developed during these periods of life and are maintained
throughout adulthood. Physical activity is a complex behaviour
that changes over the day, the week, the season, and over the
year. In reality, no one has two equal days in PA. Nevertheless,
to have a positive impact on health PA must have a regular
basis over the days.
The importance of evaluating PA in any population is on the
need of establishing (1) the current level of PA of that population and (2) to determine if its level is appropriate for health.
Most of epidemiological studies in youth indicate that boys are
more active than girls (Trost, 2002). Longitudinal studies
report that PA decline with age mainly between childhood and
adolescence and during adult age (Telama & Yang, 2000;
Kimm, et al., 2000; Mechelen et al., 2000).
In Portugal most of the studies carried out with youth use selfreport methods to assess PA. Although, these studies have
important new knowledge about PA of Portuguese children and
adolescents, it seems to us that is necessary a more precise and
objective understanding about the PA characteristics of
Portuguese children and adolescents population. Therefore, the
purpose of this study was to evaluate age and gender differences in PA of children and adolescents, using accelerometry as
an objective method of PA evaluation.
Methods
Sample
Sample size comprises 158 individuals (81 female, 77 male)
grouped as follows: group 1 aged 6 to 10 years, n = 60 (26
boys and 34 girls); group 2 aged 11 to 13 years, n = 63 (33
boys and 30 girls); and group 3 aged 16 to 18 years, n = 35
(21 boys and 14 girls).
Physical Activity Measure
PA was evaluated for 7 consecutive days with the Computer
Science and Applications Inc. (CSA) 7164 activity monitor. The
CSA is a uniaxial accelerometer designed to detect vertical acceleration ranging in magnitude from 0.05 to 2.00 Gs with frequency of 0.25-2.50 Hz. These parameters values allow the detection
of normal human motion and will reject motion from other
sources such as riding in a car and machinery operation. The filtered acceleration signal is digitised and the magnitude is
summed over a user-specified time interval (epoch). At the end
of each interval, summed value or activity count is stored in
memory, and the integrator is reset (Computer Science and
Application, Inc., 1995). For this study, a 1-min epoch was used.
Subjects were instructed to wear the CSA during waking hours.
Monitors were attached to an elastic belt worn firmly over the
waist. Subjects were instructed not to remove the device,
except for bathing, swimming or sleeping. Each subject had to
147
revista
19.9.03
0:50
Página 148
register in a sheet the time that they worn the monitor.
The stored activity counts were download to a computer for
subsequent data reduction and analysis. The CSA data was
reduced to bouts (20, 10, and 5 min.) of sustained moderate,
and vigorous PA, as well to minutes spent in moderate-to-vigorous (3-5.9 METs) PA (MVPA), vigorous (6-8.9 METs) PA
(VPA), and very vigorous (≥ 9 METs) PA (VVPA), with a QBASIC program (Trost et al, 2002). The age-specific count ranges
corresponding to the above intensity levels were derived from
the energy expenditure prediction equation developed by
Freedson et al. (1997):
METs = 2.757 + (0.0015 * counts*min-1) – (0.08957 * Age[yrs]) –
(0.000038 * counts*min-1 * Age[yrs])
Statistical Analyses
Factorial ANOVA (gender*age group) was used to test gender
and age group differences in PA variables. VVPA was excluded
from the analysis because mean scores are zero or close to zero
in all groups. All statistical analysis were done in SPSS 10.0.
Statistical significance was set at p≤0.05.
Results
In Figures 1 and 2 are displayed the means and standard deviations for daily MVPA and VPA respectively. ANOVA results
indicate no gender*age group interaction effects both in MVPA
and VPA. Significant differences were found in daily MVPA and
VPA both in boys and girls and among age groups, with daily
MVPA and VPA exhibited a significant inverse relationship
with age groups (MVPA – F(2, 152)=105.068, p<0.001; VPA F(2, 152)=28.333, p<0.001).
For MVPA, the group difference relative to the previous age
group was, in girls, about 50% in both cases. In boys the difference are of less magnitude: between group 1 and group 2 was
32%, and between group 2 and group 3 was 47.8%. For VPA in
girls the difference between group 1 and group 2 was 43.5%,
and between group 2 and group 3 was 68.3%. In boys the difference between group 1 and group 2 was 42.9%, and between
group 2 and group 3 was 32.8%.
group 3 39%. For VPA the difference in group 1 was 44.3%, in
group 2 was 45.8% and in group 3 was 200%.
Figure 2 - Mean ± SD for daily VPA by gender and age group.
Means and standard deviations for the weekly number of 20-,
10-, and 5-min bouts of MVPA and VPA are shown in Table 1
and Table 2 respectively. There was a significant decrease in
participation in bouts (20, 10, and 5-min.) of sustained MVPA
with age (20-min bout: F(2, 152)=24.365, p<0.001; 10-min
bout: F(2, 152)=31.964, p<0.001; 5-min bout: F(2,
152)=71.988, p<0.001). The decrease is in both boys and
girls, there’s no significant gender*age group interaction effect
except in 5-min bouts but this is because girls who had higher
mean value in age group 1 decreased (mean of 53% between
adjacent groups) more than boys (mean of 41% between adjacent groups). Although there was significant gender differences
(20-min: F(1, 152)=17.33, p<0.001; 10-min: F(1, 152)=7.97,
p=0.005; 5-min: F(1, 152)=3.973, p=0.048), with boys of all
age group showing significantly more bouts of sustained PA of
any kind than girls, except in 5-min bouts in age group 1. In
girls, only group 1 had a week mean of 3 bouts 20-min of sustained moderate PA, while in boys only group 3 did not have a
week mean of 3 bouts 20-min of sustained moderate PA.
Table 1: Mean±sd of weekly 20-, 10-, and 5-min bouts of MVPA
(≥3 METs) by gender and age groups
Figure 1 - Mean ± SD for daily MVPA by gender and age group.
Significant differences were found between boys and girls both
in MVPA and VPA (MVPA: F(1, 152)=5.119, p=0.025; VPA:
F(1, 152)=15.093, p<0.001). Except for MVPA in group 1
where the differences between boys and girls was only 1%,
boys of all age groups were more active than girls. The magnitude of the difference was for MVPA in group 2 34.7% and in
148
For bouts (20, 10, and 5-min.) of sustained VPA there was a
significant decrease with age, except in 20-min bouts, but the
mean in both boys and girls of the three age groups have a
mean near zero (10-min: F(2, 152)=3.279, p=0.04; 5-min:
F(2, 152)=15.341, p<0.001). The boys and girls from group 3
exhibited a mean of zero or approximately zero. In fact, boys
and girls from all age group have very few bouts of VPA over
the week. There was a significant gender differences, except in
20-min bouts (10-min: F(1, 152)=5.925, p=0.016; 5-min: F(1,
152)=11,339, p=0,001), boys participate more in bouts of sustained VPA than girls, except in 20-min bouts in group 3.
revista
19.9.03
0:50
Página 149
Table 2: Mean±sd of weekly 20-, 10-, and 5-min bouts of VPA
(≥6 METs) by gender and age groups
The decrease of PA verified along the age is pronounced in
both boys and girls, and is consistent with the preponderance
of published empirical literature, and support the idea that PA
declines with age (Sallis, 2000). Through childhood and adolescence PA decrease rapidly in the same magnitude, indicating
that the decline begin early in childhood, contrary to previous
studies that report that the declines begin in adolescence
(Mechelen et al., 2000; Telama & Yang, 2000), this contradictory results is perhaps due to the fact that only few of these studies include young children in samples. In a sample of 2309 of
both gender, Telama & Yang (2000) had find a marked decline
after the 12 years of age. Also Kim et al. (2000) report a
decline in the transition between the childhood and adolescence in a sample of 2379 children observed between 9 and 18
years of age. Yet, in a large study (n=3742) with children aged
6-10 years Lopes et al. (2003) evaluated PA with a questionnaire and found no PA decline. It is possible that the questionnaire don’t have the ability to evaluate PA as accurate as
accelerometry as. The degree of the decline in the present
study is of the same magnitude reported by Trost et al. (2002).
One limitation of the present study, and also some others
about this issue, is that they are cross-sectional nature, because
of that we couldn’t have an unshaken confidence that decline is
of the magnitude registered.
The literature report that boys are more active than girls, that
is, engage more in vigorous and in competitive PA. (e. g. Janz
et al., 1995). The results of present investigations confirm this
general idea. Across the three age groups, boys are consistently
more active than girls, and the difference is more marked in
VPA. Van Mechelen et al. (2000) in a longitudinal study
between 13 and 27 years of age, found that girls had more participation in moderate PA than boys, nevertheless, due to low
involvement of girls in vigorous PA, the boys had a significant
high values of total participation in PA. Also Mota & Esculcas
(2002) found by means of a questionnaire that adolescent girls
are significantly inactive than boy. Despite the fact that we
don’t find significant gender*age group interaction, indicating
no significant difference between boys and girls in PA decline,
the results show that the overall PA decline was grater in girls
than in boys, and this decline was even grater when we consider VPA. The consistency of these results heightens the need of
special attention, in eventual intervention programs for the
promotion of PA, in girls of all ages.
During the 7 days of observation, the children and adolescents
of the sample of this study, mostly the older, performed very
few sustained bouts of PA. In fact, only group 1 performed 3 or
more 20-min bouts of sustained MVPA. Participation in continuous 20-minutes bouts of VPA was near zero in both genders
of all age groups. Hence, it seems that principally the adolescents of the sample of this study, don’t accomplish PA recommendation of 30 minutes a day of MVPA (Cavill et al., 2001),
or 20 minutes a day of VPA (Sallis & Patrick, 1994). Even son,
there was a great participation in shorter bouts (10 and 5 minutes) of MVPA, and in younger boys there was also a remarkable participation in 5-min bouts of VPA. Perhaps these recommendations don’t have in consideration the PA characteristics
of children and youth. Children typical pattern of PA is characterize by short, intermittent bouts of VPA with frequent rest
periods of longer duration. Bailey et al. (1995) reported that in
children 95% of VPA lasted less than 15s and only 0.1% of
bouts were longer than a minute, and no bouts longer of 10
minutes was recorded. The median duration of low and moderate PA was 6s while the duration for VPA was 3s. Maybe the
criteria for define the duration and frequency of PA, that are
based on more structured, adult-patterns of activity, are not
appropriate for children. Welk et al. (2000) propose that a better criterion to define frequency would emphasize the accumulation of intermittent activity throughout the day. Depending
on the approach used, an appropriate criterion for children
might be the percentage that reports 2-3 bouts of short, intermittent activity totaling 30-60 minutes on at least 5 days a
week. The mode of PA is also different between older and
younger subjects, older subjects are described as involved in
more formal PA, while younger mostly chose informal PA
whatever their level of PA (Mota & Esculcas, 2002).
In summary, we found that boys of all ages are more active
than boys, the adolescent, that is the older group (16-18 years
of age) of both gender do not comply with physical activity
guidelines which recommend 20-min a day of MVPA. We also
found that the older groups of both gender had significantly
lesser PA than the older ones, however, due the cross-sectional
design of this study we can’t make definitive conclusions concerning age-related trends in physical activity. Therefore, it is
recommended longitudinal objective monitoring studies with
long-term follow-up.
Acknowledgement
We would like to thank Stewart Trost for sending us a special
software to hand data reduction in PA bouts.
References
Bailey, R. C. et al. (1995). Med. Sci. Sport Exerc. 27: 1033-1041
Blair, S. N. (1993). Res. Q. Exer. and Sport, 64: 365-376
Cavill, N.; Biddle, S.; Sallis, J. F (2001). Ped. Exerc. Sci. 13: 12-25
Computer Science and Application, Inc. (1995). Activity monitor operators manual. Model 7164 Multimode. Shalimar, FL.
Freedson, P. S.; et al. (1997). Med. Sci. Sport Exerc. 29 (supp): S45
Janz, K. F.; Witt, J. Mahoney, L. T. (1995). Med. Sci. Sport Exerc.
27: 1326-1332
Kimm, S. Y. S. et al. (2000). Med. Sci. Sport Exerc. 32: 1445-1454
Kimm, S. Y. S. et al. (2000). Med. Sci. Sport Exerc 32: 1445-1454
Lopes et al. (2003). Rev. Brasileira Cien. Mov. In press.
Mackelvie, K. J. et al. (2001). Med. Sci. Sport Exerc. 33: 1818
Mechelen, Van W. et al. (2000). Med. Sci. Sport Exerc. 32: 1610-1616
Mota, J.; Esculcas, C. (2002). Int. J. of Behav.l Med.
Riecham, S. E. et al. (2002). Obes. Res. 10: 1065-1073.
Sallis, J. F.; Patrick, K. (1994). Ped. Exerc. Sci. 6: 302-314
Sallis, J. F. (2000). Med. Sci. Sport Exerc. 32: 1598-1600
Telama, R., & Yang, X. (2000). Med. Sci. Sport Exerc. 32: 1617-1622
Trost, S. G. et al (2002). Med. Sci. Sport Exerc. 34: 350-355
Vuori, I. M. (2001). Med. Sci. Sport Exerc. 33(6), 551
Westerterp, K. R. G., M. I. (1997). Int. J of Obes. 21: 184-188
Williams, P. T. (2001). Med. Sci. Sport Exerc. 33: 754-761
149
revista
19.9.03
0:50
Página 150
GENDER DIFFERENCES IN PHYSICAL ACTIVITY DURING RECESS
IN PORTUGUESE PRIMARY SCHOOLS
Mota Jorge1, Stratton Gareth2
1 Research Center in Physical Activity, Health and Leisure, Faculty of
2 Liverpool John Moores University, UK
Keywords: children, playground, activity
From a preventive point perspective, it makes sense to make
sure that current low level of physical activity in young people
and in particular gender differences are challenged. Because
children spend a large portion of their day in school, it is
important to examine physical activity levels of boys and girls
in this environment (Sarkin et. al., 1997). Given that children
spend up to 20% of their school week in play, primary school
playgrounds provide an ideal setting for measuring children’s
PA (Stratton and Mota, 2000). Therefore, the purposes of this
study were: (1) To measure the physical activity levels of children aged 8-9 years-old during a recess school period; (2) To
investigate the gender differences in PA during unstructured
recess period.
Thirty-nine Portuguese school children (16 boys; 23 girls) aged
8-9 years old took part in the study. Heart rate (HR) was
assessed during morning recess, over 4 weeks during the
spring term. (Polar Electro Oy, Kempele, Finland). Percentages
of recess time spent in MVPA were calculated according
Stratton (1996). The HR records were grouped into five time
categories: (1) 15s–60s; (2) 60s–3 min; (3) 3min–5min; (4)
5min–10 min and (5) >10 min. The level of significance was
set at p≤0.05.
Mean HR during recess of girls (138.3 beats·min-1) was significantly (p<0.001) higher than boys (125.7 beats·min-1). Thus
the results indicated that girls experience higher cardiorespiratory load than males during school play. Boys spent 19%
(approximately 4 min) and girls 34% (approximately 6.30 minutes) in MVPA indicating that low levels of PA are evident during school recess. The data showed that patterns of activity
were sporadic and that children rarely engage in health promoting physical activity during recess. Girls were generally
more active than boys, which may be a result of an equal
opportunity to play in this setting. Thus, low levels of MVPA
only provide a rationale for a greater play stimulus during
recess. Thus strategies to enhance children physical activity at
school recess playtime should be developed.
PHYSICAL ACTIVITY, BODY COMPOSITION AND OBESITY
ACCORDING TO MATURACIONAL STAGE
Ribeiro José C, Guerra Sandra, Duarte José AR, Mota Jorge
Research Centre in Physical Activity, Health and Leisure Faculty of
Keywords: physical activity, children, maturation
Obesity is one of the most serious health problems in industrialized countries and has been linked to low physical activity
150
(PA) levels. Recently the importance of regular PA for youth
has been positively connected to many health measures and
because within a given chronological age group, some children
may be advantaged or disadvantaged in the performance of
some physical fitness tests due to their maturity status it’s
important to understand the associations between these factors. A positive, and strong relationship between the amount of
PA or cardiovascular fitness and health status does exist in the
adult population. This relationship is not clear for children and
adolescents, and normal growth and maturation during adolescence may further obscure the association. The aim of the present study was to establish the associations between PA, obesity
and biological maturation in children’s and adolescents. A random sample of 1444 (8-15 years of age) children, 686 males
(age, 10.8±2.3; weight, 40.4±12.5; height, 142.9±13.8; BMI,
19.4±3.4) and 758 females (age, 10.9±2.4; weight, 40.8±12.5;
height, 142.6±13.2; BMI, 19.6±3.5) were evaluated from Porto
region. Body Mass Index (BMI) was calculated from the children’s height and weight [weight (Kg)/height2 (m)].
Children’s were classified as obese according to Cole et al.
(2000). An adapted version of the “Weekly Activity Checklist
Questionnaire” developed by Sallis et al. (1993), was applied to
the sample for the diagnosis of their PA. Sexual maturity was
determined according to Tanner’s (1962). Our results reveal
that BMI, weight and height increase with biological maturation. We also observed that PA decreases by biological maturation augment, both in boys and girls. Along biological maturation stages we found that the percentages of obese girls
decreases (p<0.01), whilst in boys there is a decrease from
pre-pubertal to pubertal stages and then an increase from
pubertal to post-pubertal stages (p<0.05). PA levels decrease
with biological maturation, both in boys and girls.
GENDER DIFFERENCES IN PHYSICAL ACTIVITY
DURING RECESS TIME
Santos Paula, Silva Pedro, Guerra Sandra, Ribeiro José C,
Oliveira José, Duarte José AR, Mota Jorge
Research Centre in Physical Activity, Health and Leisure, Faculty of
Keywords: physical activity, children, playground
The purposes of this study were: (1) To observe the participation into MVPA during recess at school period in children aged
8-10 years-old; (2) To determine the relative importance of
physical activity levels during recess at school in overall daily
physical activity; (3) To investigate the gender differences in PA
during unstructured recess period. The participants of this
study comprised 22 school children (boys n=10; girls n=12)
aged 8-10 years old from 3rd and 4th school grade. Daily totals
for the physical activity variables were calculated by summing
the values from 13 hours of physical activity measurements
(9:00 to 22:00), with 60-min time blocks comprising each day.
The recess time (minutes) was drawn from the data collected
as follows: morning period 10:30 to 11:00 and afternoon period
15:30 to 16:00.Our data did not showed differences among
boys and girls in daily total counts and overall time spent in
MVPA, while girls were more engaged in MVPA activities dur-
revista
19.9.03
0:50
Página 151
ing recess time than boys. However, girls were significantly
(p<0.05) more involved (38.0%) in MVPA during recess time
than boys (30.8%). Participation in MVPA during recess contributes significantly more (p<0.05) in girls (19.0%) than boys
(15.4%) for the total amount required by international healthrelated PA guidelines, while the percent of time engaged in
MVPA during recess time at school accounts in small amount
for (6.5% boys and 8.3% for girls) daily MVPA. Results of this
study suggest that unstructured time during the school day
might be designed to provide encouragement and opportunities
for all students to be physically active.
THE RELATIONSHIP BETWEEN 4-7 DAY ACCELEROMETRY
MEASURES OF PHYSICAL ACTIVITY, CALCIUM INTAKE
AND BONE DENSITY IN BOYS AND GIRLS, AGED 8-11 YEARS
mean time spent in very hard, hard, vigorous, moderate, low
intensity activities were used as the output measures for physical activity. Calcium intake was estimated by a four-day weighted food diary. Bone mineral content (BMC) and areal density
(BMD) were measured at the total body (TB), proximal femur
(PF) and femoral neck (FN) using dual energy X-ray absorptiometry. Multiple regression analyses were used to assess the
contribution of total physical activity and above vigorous activity to BMC, residualised for bone area and body mass (BMCR),
after accounting for calcium intake.
Results
Boys were taller, had higher BMD at the TB, PF and FN, spent
less time in low intensity activity and more time in moderate, vigorous and hard intensity activity than the girls (p<.05, Table 1).
Table 1. Descriptive statistics (mean ± SD)
Powell Sarah M1, Rowlands Ann V1, Eston Roger G1,
Ingledew David K2
1
School of Sport, Health and Exercise Sciences
School of Psychology University of Wales, Bangor, Wales, United
Kingdom
2
Keywords: exercise, bone, densitometry
Significant gender difference = * p<.05, † p<.01.
Introduction
The accrual of bone mass during childhood and adolescence is a
critical factor associated with the prevention of osteoporosis.
There is no cure for osteoporosis once the disease is established, and a large amount of bone will have already been lost
by the time of fracture (Lysen and Walker, 1997). At least 90%
of total bone mass is accrued by the end of adolescence (Glastre
et al., 1990). It is therefore important to maximise bone accrual
during childhood in order to reduce subsequent loss.
Although there is evidence for a positive relationship between
habitual physical activity and bone mineral density in children
(Gunnes and Lehmann, 1996, McKay et al., 2000, Kemper et
al., 2000, Lloyd et al., 2000, Bailey et al., 1999, Jones and
Dwyer, 1998, Rowlands et al., 2002), the research appears to
be confounded by the accuracy of measures of physical activity.
Conceptually, the ideal solution for the assessment of physical
activity is the use of monitors that actually measure or track
movement. Accelerometers measure the accelerations of movement. The RT3 accelerometer is a small, lightweight triaxial
accelerometer which stores activity data for up to 21 days. The
three dimensional measure is potentially important when
assessing activity.
Therefore, the aims of this study were i) to determine the relationship between habitual physical activity assessed by tri-axial
accelerometry, calcium intake, and bone measures in prepubertal children and ii) to investigate the relationship
between vigorous intensity activity and bone measures in prepubertal children.
Methods
Ninety-eight children, aged 8-11 years, wore accelerometers for
up to seven days to assess activity. All children wore the
accelerometer for a minimum of four days. The accelerometer
was programmed to record minute-by-minute activity counts.
The mean daily activity count on the X axis (total activity), and
At the total body, total activity was a significant predictor of
BMCR in girls (R2 = 17.6%, p<.05), but not boys. At the proximal femur and femoral neck, total activity was a significant
predictor of BMCR in boys (R2 = 12.1% and 10.2%, respectively, p<.05) but not girls.
Conclusions
This study has provided evidence for an association between
total activity and size-adjusted BMC at the total body in girls,
and at the proximal femur and femoral neck in boys. These
relationships persist after controlling for calcium intake. A
strength of this study was the use of minute by minute
accelerometry recordings of each child for at least four days to
assess physical activity. This will have reduced the measurement error associated with the assessment of activity (Jones
and Dwyer, 1998).
References
Lysen, V.C. and Walker, R. (1997). J. Sch. Health, 67:317-22
Glastre, C., Braillon, P., David, L., Cochat, P., Meunier, P.J. and
Delmas, P.D. (1990). J.Clin. Endocrinol. Metab., 70:1330-3
Gunnes, M. and Lehmann, E.H. (1996). Acta. Paediatr., 85:19-25
McKay, H.A., Petit, M.A., Scultz, R.W., Prior, J.C., Barr, S.I. and
Khan, K.M. (2000). J. Pediatr., 136:156-62,
Kemper, H.C., Twisk, J.W., van Mechelen, W., Post, G.B., Roos, J.C.
and Lips, P. (2000). Bone, 27:847-53
Lloyd, T., Churchill, V.M., Johnson-Rollings, N., Kieselhorst, K., Eggli,
D.F. and Marcus, R. (2000). Pediatrics, 106:40-4
Bailey, D.A., McKay, H.A., Mirwald, R.L., Croker, P.R.E. and
Faulkner, R.A. (1999).J. Bone Miner. Res., 14:1672-9
Jones, G. and Dwyer, T. (1998). J. Clin. Endocrinol. Metab., 83:4274-9
Rowlands AV, Powell SM, Eston RG, Ingledew DK. (2002). Ped.
Exerc. Sci., 14:358-68
151
revista
19.9.03
0:50
Página 152
THE INFLUENCE OF ANTHROPOMETRICAL PARAMETERS
TO THE BODY COMPOSITION MEASURED BY DXA AND BIA
IN 11–13 YEAR OLD CHILDREN
Leppik Aire, Jürimäe Jaak, Jürimäe Toivo, Sööt Terje
University of Tartu, Tartu, Estonia
Keywords: body composition, anthropometry, children
The aim of this study was to investigate the possible relationships between anthropometrical parameters and body fat%
measured by DXA and BIA in 11-13 year old boys (n=27;
11.8±0.7 yrs; 152.8±8.5 cm; 39.4±6.3 kg; BMI: 16.8±1.5
kg/m2) and girls (n=26; 12.2±0.7 yrs; 156.5±7.2 cm; 45.2±8.3
kg; BMI: 18.4±2.5 kg/m2). Children were at Tanner stage 2 or
3. Children participated in 2-3 compulsory PE lessons per week.
In total, 9 skinfolds, 13 girths, 8 length and 8 breadths/lengths
were measured according to ISAK instructions (Norton & Olds,
1996). Body impedance was measured with a multiple-frequency impedance device (Multiscan 5000, UK) at 50 kHz. Both
resistances at 50 kHz and resistance index height2/resistance2
were used. Body composition (body fat%) was assessed by DXA
(Lunar Corp, Madisson, WI, USA). Stepwise multiple regression analysis indicated that supraspinale and iliac crest, and
abdominal from the measured skinfolds characterized 92.2 and
61.8% (R2x100) of the body fat% measured by DXA in boys
and girls, respectively. Thigh girth from the measured girth
parameters characterized 61.8 % in boys and 53.8 % in girls.
The length parameters did not influenced body fat% measured
by DXA. The influence of breadth/length parameters to the
body fat% was relatively low but significant (in boys biacromial
characterized 42.4% and in girls femur characterized 21.0% of
the total variance). Body fat% measured by BIA was mostly
influenced by the girth of small joints – wrist in boys (57.8%)
and calf and neck (50.2%) in girls. We can conclude that body
fat% measured by DXA or BIA highly depend on specific measured anthropometrical parameters.
SOMATIC CHARACTERISTICS AND PHYSICAL FITNESS
IN YOUNG PLAYERS OF BASKETBALL FROM AMAZONAS, BRAZIL
Moura Walcymar1, Tavares Fernando2, Negreiros Núbio2
1
Federal University of Amazonas, Brazil
2
Keywords: somatic characteristics, physical fitness, basketball
Keywords: body composition, physical activity, children
Introduction
In the investigation of the players differentiated performance
one of the concerns is to try to identify their individuals characteristics with the purpose to optimise the performance. In
basketball, the evaluation of the players performance has been
praised by different specialists and investigators (Maia, 1993;
Janeira, 1994; Pinto, 1995; Brandão, 1995). The specialized literature emphasize the importance of the somatic characteristics and the physical fitness, using for its evaluation specific
tests which allows to obtain specific information. The purpose
of this study is to evaluate and compare by gender the somatic
characteristics and physical fitness in young players of basketball from Amazonas, Brazil.
There is a growing concern in the world about the increasing
prevalence of overweight and obesity in adults and children. In
the case of children the data available is not uniform because
the criteria for diagnosis of overweight and obesity is still
under studies. The Body Mass Index (BMI) has been commonly
used for nutritional assessment of adults but only in recent
years it has been utilized for children. The aim of this study
was to assess the impact of overweight on functional aspects of
physical activities related to health in schoolchildren. The chil-
Methods
The sample comprises 79 players of basketball, 43 boys and 36
girls, 15 to 18 years of age was selected from Amazonas, Brazil.
The evaluated indicators of the somatic characteristics had
been: height, weight, arm span, hand length (stylion-dactylion)
(HL) and transversal hand length (THL).
Physical Fitness was assessed according to the AAHPERD
Youth Fitness Test, which is composed by the Sit-Ups, Shuttlerun, Standing Long Jump, 50-Yard dash, 12- Minute Run.
THE EFFECT OF OVERWEIGHT AND BODY FAT
ON PHYSICAL ACTIVITIES RELATED TO HEALTH
IN MALE SCHOOLCHILDREN AGE 7 TO 10 YEARS OLD
Guerra Tasso C1, Giugliano Rodolfo2
1 Centro Universitário do Leste de Minas Gerais,
UNILESTE, MG, Brazil
2 Universidade Católica de Brasília, DF, Brazil
152
dren were classified according to the BMI international standard per age (CDC, 2001) in normal children, between the 25th
and 75th centile, and overweight children those between 85th
and 95th centile (Dietz & Bellizzi, 1999). The research evaluated male children, age 7 to 10 years, of a private school in the
city of Ipatinga, Minas Gerais (Brazil). Initially the height and
weight were measured in 271 children to obtain the Body Mass
Index and classify the children in groups of normal and overweight. From this group 50 normal children and 50 overweight
children were selected randomly. Triceps and subscapular skin
fold were measured from those children in order to calculated
body fat (Slaughter, et al 1988). The two groups were submitted to tests to check the flexibility, measured by seating and
reaching test, the muscle strength/muscle resistance, measured
by the modified abdomen test, and the cardiorespiratory fitness, measured by the nine-minute running/walking test. The
results show significantly better performance in a normal
group for the cardiorespiratory fitness test compared with the
overweight group (p<0,05). The other tests were similar comparing both groups. It was observed a significant correlation,
using the Pearson correlation test, between body fat and BMI
and cardiorespiratory fitness. The study showed that the body
fat was inversely related to cardiorespiratory fitness in overweight children however it does not seem to influence the flexibility, muscle strength and muscle resistance.
revista
19.9.03
0:50
Página 153
T-test of independent measures was used for the comparison of
the averages in each one of the indicators of performance identifying the variables that best discriminates the groups (Male
and Female). For testing means between groups by sex and
specific positions in game (Guard, Forward and Post), Factorial
ANOVA was used, followed by a post-hoc Shéffé F test. The pvalue* 0.05 was chosen to accept statistical significance.
Results
The Table 1 presents the results of the comparisons among relative averages to the somatic characteristics in the male and
female sex. In all the variables the male players present superior values, with evidence for the indicators to the hand lenghts
(HL and THL) in that the male players’ differences statistically
significant are verified in relation to the female.
significant is verified between Forward and the Post relatively
to the indicator weight and among the Guard and Forward and
Forward and the Post in relation to the indicator arm span.
In the other indicators it is verified that the Post presents
medium superiors results than the Guards and Forwards, with
exception of the hand lengths.
Table 3 - Comparison of the mean values of the somatic
characteristics and the physical fitness for the female group
according the specific positions in game (Guard, Forward and Post).
Table 1 - Comparison of the mean value (cm)
of the somatic characteristics for the male and female sex
Comparison a posteriore(Scheffé F-test)
(1) Forward vs. Post (0,047)
(2) Guard vs. Forward (0,034) and Forward vs. Post (0,019)
(*) Statistically significant (≤ 0.05)
Table 2 presents the average values obtained in the physical fitness tests among the male and female sex. Among the considered variables, we verified that Shuttle-run, 50 Yard and the
12-Minute run, present differences statistically significant male
in relation to the female.
Table 2 - Comparison of the mean value of the physical
fitness indicators for the male and female sex
Specific positions in game: male group
The Table 4 presents the comparison of the mean values of the
somatic and physical fitness indicators for the male group in
according to the specific positions in game (Guard, Forward
and Post). They were found differences statistically significant
only in the somatic characteristics, just as in the female group.
Of enhancing, the existence of some balance found in the
medium values of the remaining indicators and in relation to
the players’ positions.
Table 4 - Comparison of the mean values of the somatic characteristics
and the physical fitness for the male group in agreement with the specific positions in game (Guard, Forward and Post).
(*) Statistically significant (p≤ 0.05)
Specific positions in game: female group
The Table 3 presents the comparison of the mean values of the
somatic characteristics and physical fitness for the female
group in agreement with the specific positions in game (Guard,
Forward and Post). The existence of differences statistically
Comparison posteriori (Scheffé F-test)
Guard vs. Forward (=,042); Guard vs. Post (0,000); Forward vs. Post
(0,000). Guard vs. Post (0,023). Guard vs. Forward (0,009); Forward
vs. Post (0,000); Forward vs. Post (0,005). Guard vs. Post (0,041)
153
revista
19.9.03
0:50
Página 154
Conclusions
We can conclude that the male basketball players from Amazonas
(Brazil), concerning the somatic characteristics, are taller, are
heavier and their up-limbs are bigger, and they show differences
statistically significant in the hand lengths than on the female
players. They are also better in all physical fitness indicators, with
special evidence in shuttle-run, 50-yard dash and 12 minute run,
were we found differences statistically significant .
Concerning the players specific positions in the game (Guard,
Forward and Post) we have found differences in the performance indicators studied in both groups (female and male) with
special evidence to the somatic characteristics where we have
verified differences statistically significant.
References
Brandão, E (1995). A Performance em Basquetebol: Um estudo multivariado no escalão de cadetes masculino. Master thesis, Faculty of Sport
Sciences and Physical Education, University of Porto, (not published)
Filardo, R.; Anez, C.; Neto, C. (2000). Revista Brasileira de
Cineantropometria & Desempenho Human, 2 (1): 66-71
Glaner, M. (1999). Revista Brasileira de Cineantropometria &
Desempenho Humano, 1, (1):69-81
Hopkins, D. (1977). The Reasearch Quarterly, 48, ( 3): 535-40
Janeira, M. (1988). Perfil Antropometrico do Jogador de Basquetebol
no Intervalo Etário de 13-15 anos e a sua Relação com os Níveis de
Eficácia no Jogo. Master thesis, Superior Institute of Physical
Education, University of Porto, (not published)
Janeira, M.; Maia, J. (1992). A generalized discriminant function for
classifying young females basketball players. In: Olympic Scientific
Congress, Benalmádena, Spain.
Janeira, M. (1994). Funcionalidade e Estrutura de Exigências em
Basquetebol. Um estudo univariado e multivariado em atletas séniores
de alto nível. Doctoral thesis, Faculty of Sport Sciences and Physical
Janeira, M.; Nhantumbo, L. (2000). A força explosiva dos basquetebolistas Moçambicanos. Um estudo exploratório em atletas seniores
masculinos. In: 10 Anos de Actividade Científica, Lisboa, Anais.
Lisboa: CEFD-UPM/FCDEF-UP, 1990 –1999. 256-60
Maia, J. (1993). Abordagem Antropobiológica da Selecção em
Desporto: Estudo multivariado de indicadores bio-sociais da selecção em
andebolistas dos dois sexos dos 13 aos 16 anos de idade. Doctoral thesis, Faculty of Sport Sciences and Physical Education, University of
Porto, (not published)
Nhantumbo, L; Bernardo, I. (2000). Perfil Somático e de Aptidão
Física do Basquetebolista Moçambicano de Acordo com a Posição
Específica Desempenhada no Jogo. Estudo descritivo e comparativo em
atletas séniores masculinos baseado em testes de terreno. In: 10 Anos
de Actividade Científica, Lisboa, Anais. Lisboa: CEFD-UPM/FCDEFUP, 1990 –1999. p. 262-68.
Pinto, D. (1995). Indicadores de Performance em Basquetebol:
Estudo descritivo e preditivo em cadetes masculino. Master thesis,
Porto, (not published)
TERM TIME AND HOLIDAY PHYSICAL ACTIVITY PATTERNS
OF 7 TO 9 YEAR OLD GIRLS
Stevens Sarah L1, Rowlands Ann V2
1
154
Chester College of Higher Education, UK
2 School of Sport, Health and Exercise Sciences, University of Wales,
Bangor, UK
Keywords: accelerometer, season, moderate intensity physical activity
Aim: Objective measures are recommended when assessing
children’s physical activity (PA). However, most studies utilizing an objective measure of PA in children have used a one off
measurement period, typically during term time. As PA is
known to vary between school and non-school days, and across
season, this may not be representative of overall PA. The aim
of this study was to compare PA patterns of 7-9 year old girls
during term time (TT) and summer holiday (SH) using
accelerometry.
Method: Twenty eight girls [(mean±sd) age, 8.8±0.9 yrs:
height, 129.5±5.4 cm; mass, 28.9±5.9 kg] were recruited from
schools in the local area. Physical activity was assessed using
triaxial accelerometry (RT3, Stayhealthy Inc., Monrovia,
California) for up to seven days over both TT and SH periods
[6.5 ± 0.6 days and 5.8 ± 1.1 days, respectively]. Minutes
spent in moderate (3 to <6 METS) and > vigorous (> 6
METS) intensity PA were calculated using pre-defined cut-off
points. A median split, using an aggregate value of total PA as
the central tendency, was used to classify the girls as either
high- or low- active.
Results: Two-way ANOVAs revealed group x time interactions
for total PA counts (F1, 26 = 6.118, P<0.05) and minutes
spent in >vigorous intensity (>vig) PA (F1, 26 = 5.829, P <
0.05), but not time spent in moderate activity. Post-hoc tests
revealed high active girls had higher total PA counts than low
active girls during both TT [463598.26 ± 73926.2 cf. 404936 ±
63839.8 counts, P 0.05] and SH [494333.30±10894.6 cf.
322479.72±60590.7, P<0.05]. However, while low active girls
had lower PA counts during SH than TT (P<0.05), high active
girls maintained the same activity levels during SH and TT.
Low active girls spent less time in >vig PA than high active
girls during SH (24.2±11.4 mins cf. 52.6±21.6 mins, P<0.05),
but not during TT (34.0±14.2 cf. 44.9 ±13.2 mins, P>0.05).
Conclusion: Activity levels of low active girls appear to be lowered further in holiday time, relative to term time. This provides compelling evidence as to the potential benefits of school
as an institution for promoting PA in girls, particularly those
who exhibit low activity behaviours. It is recommended that
studies using an objective measure of PA account for school
days, non-school days and seasonal variation when assessing
activity levels in children.
INFLUENCE OF SOCIOECONOMIC STATUS IN PHYSICAL FITNESS:
A STUDY IN AFRICAN SCHOOL-AGED POPULATION
Saranga Silvio1, Maia José AR2, Prista António1, Lopes Victor3,
Marques António2
1 Faculty of Physical Education and Sport Sciences, Universidade
Pedagógica, Mozambique
2 Faculty of Sport Sciences and Physical Education, University of
Porto, Portugal
3 School of Education, Polytechnic Institute of Bragança, Portugal
Keywords: fitness, africa, socio economic status
revista
19.9.03
0:50
Página 155
The main purpose of this study was to analyze the influence of
socioeconomic status (SES) in physical fitness in an African
urban school aged population. Sample size comprises 1199
males and 1304 females aged 7 to 17 years from Maputo,
Mozambique. Physical fitness was evaluated according to nine
items: sit and reach, trunk lift, sit-ups, standing long jump, arm
hang, curl up, handgrip, 10x5 meters run and one mile
walk/run. Subjects were divided in three groups according to
their socio-economic status: low, average, and high. Data analysis consisted of ANCOVA using SES as factor and age, maturity
stage and body mass as covariates. All calculations were done in
SPSS 10. Results showed significant difference among groups in
almost all tests. Controling for age, maturity status and body
mass index, subjects from the low SES group have significant
higher performance in sit and reach (Fb(boys)=131.5;
Fg(girls)=187.0), trunk lift (Fb=28.8; Fg=22.9), flexed arm
hang (Fb=3.0; Fg=4.8), handgrip (Fb=23.9; Fg=123.4) and 1
mile run (Fb=157.0; Fg=258.1). High SES group performed
better in sit-ups (Fb=44.5; Fg=35.8), curl-up (Fb=7.0;
Fg=9.2) and 10x5 meters (Fb=24.9; Fg=4.0). In standing long
jump differences were only significant in boys (Fb=17.1) favoring the high SES group. It was concluded that (1) the better
performance of the low SES group may be linked to higher
physical activity levels associated to survival activities and recreational outdoor games observed in this population, and (2)
results in fitness tests favoring high SES group may be influenced by a socio cultural effect.
ratio of body mass raised to the power of 0.75 (SVO2). Mean
activity counts, across all activities were 6811.5±2442.7
counts.min-1 (Tritrac) and 7490.5±2987.2 counts.min-1 (RT3).
Activity measured by Tritrac vector magnitude (Vmag) and RT3
Vmag both correlated significantly with SVO2 (r = 0.867 and r
= 0.873, respectively; p<0.01) for all activities combined. RT3
Vmag and heart rate combined was the best overall predictor of
SVO2 (R2 = 0.818, p<0.01). Bland and Altman plots showed
RT3 counts were consistently higher than Tritrac counts (mean
bias = 544.0 counts, 95% limits = ± 840.8 counts). However,
the difference between RT3 and Tritrac counts increased as the
mean of RT3 and Tritrac counts increased. This study supports
previous research showing a strong linear relationship between
the Tritrac counts and SVO2. Prediction of SVO2 by the RT3
was as good as the Tritrac and this, combined with the RT3s
smaller size, makes it a suitable alternative to the Tritrac.
However, there is a lack of agreement between the two
accelerometers. As the Tritrac is no longer available, this limits
comparison of RT3 data with previous research.
A MIXED-LONGITUDINAL STUDY OF SOMATIC GROWTH,
PHYSICAL ACTIVITY, HEALTH-RELATED PHYSICAL FITNESS AND
MOTOR CO-ORDINATION IN CHILDREN FROM VISEU, PORTUGAL
Ferreira João V1, Maia José AR2, Lopes Vítor P3
1
2
COMPARISON OF THE VALIDITY OF THE TRITRAC
AND RT3 TRIAXIAL ACCELEROMETERS
FOR ASSESSMENT OF CHILDREN’S PHYSICAL ACTIVITY
Rowlands Ann V, Thomas Philip WM
School of Sport, Health and Exercise Sciences, University of Wales,
Bangor, United Kingdom
Keywords: oxygen consumption, vector magnitude, heart rate
When assessing children’s physical activity it is recommended
that objective measures e.g. accelerometry, heart rate or
pedometry are used. The Tritrac triaxial accelerometer (T303A,
Reining International Professional Products, Wisconsin, USA)
has been shown to be a valid measure of physical activity, but
has recently been replaced with the RT3 (Stayhealthy Inc.,
Monrovia, CA); a smaller and more user-friendly accelerometer.
The purpose of the present study was to compare the validity
of the Tritrac and the RT3 for predicting oxygen consumption
during a range of typical children’s activities. Nineteen boys
(mean age 9.5±0.8 years, height 137.8±6.9 cm, body mass
33.5±5.4 kg) took part in the study. Each child carried out
seven different activities: four regulated activities (walking at 4
and 6 km.h-1 and running at 8 and 10 km.h-1) on a treadmill
and three unregulated play activities (computer game, kicking a
football to and fro, and playing hopscotch). Each activity was
carried out for four minutes, with the exception of the computer game (ten minutes). Heart rate and oxygen consumption
were measured in the last minute of each activity. The Tritrac
and RT3 were securely fixed to a belt and worn above the left
and right hip, respectively. Oxygen uptake was expressed as a
3
School of Education, Polytechnic Institute of Viseu, Portugal
Faculty of Sport Sciences, University of Porto, Portugal
Keywords: longitudinal, somatic growth, physical activity, coordination
The Portuguese educational system felts a strong need for longitudinal information, particularly in the Physical Education
setting of children. The research program that we are going to
briefly outline aims at the fulfillement of this gap, although it
will be based primarily on a population from a city located in
the center of Portugal – Viseu.
The main aims of this large study are: (1) to investigate change
and stability in somatic growth (SG), physical activity (PA),
health-related physical fitness (HRPF), and motor co-ordination
over a 4 year period; (2) to study the tracking of the main items
involved in the several domains of the study; (3) to model
change and its predictors at the individual and school levels,
and to (4) search for important clues regarding intraindividual
changes in interindividual differences with the framework of
structural equation modeling and hierarchical modeling.
Sample size comprises 900 subjects of both genders and was
divided in two cohorts: cohort 1 (baseline age of 6 years, n =
450); cohort 2 (baseline age of 9 years, n = 450). This is a
missing-by-design study with an overlapping age of 9 years. We
shall cover a period of 7 years, i.e., from 6 to 12 years (main
years related to the first years of official schooling where
mandatory physical education classes will involve children in
their first approaches to formal sports).
For most of the domains of the study a yearly evaluation will
be scheduled. For the somatic domain, evaluation takes place
two times a year.
Somatic measurements will be comprised of height, weight,
sitting height and body mass index (BMI). Health-related
155
revista
19.9.03
0:50
Página 156
physical fitness will be assessed with the “Prudential
Fitnessgram” test battery, which is composed of one-mile runwalk, trunk-lift, push-up, curl-up, and body composition. Some
performance-related fitness tests are also conducted: shuttlerun of 10x5 meters, 50 meters dash, standing long jump, hand
grip. Motor co-ordination will be evaluated with the KorperKoordinationstest fur Kinder (KTK) test battery which includes
4 tests: walking backwards on beams of decreasing width,
jumping with each leg separately over an increasing number of
foam plates, jumping laterally to and from with both legs, and
moving across the floor by stepping from one plate to second
plate, then relocating the first plate, then taking the next step,
etc. Physical activity will be assessed with different protocols:
(1) the Godin & Shephard questionnaire will be used with the
first cohort; (2) the Baecke et al. questionnaire will be used
with the second cohort; (3) a seasonal evaluation of PA patterns will be assessed with the CSA accelerometer in 60 children for 7 days.
Data analysis will use most of the available models for change
within the structural equation modeling approach, i.e. Markov
and Wiener for the study of tracking, and latent growth and
mixture models for the study of change over time, including, of
course, fixed and non-fixed predictors. We shall use also a multilevel or hierarchical approach to study predictors of performance in different levels, i.e., students and schools.
PARENTAL INFLUENCES AND OTHER DETERMINANTS OVER
THE LEVELS OF PHYSICAL ACTIVITY AND SPORTS PERFORMANCE
BY CHILDREN AND TEENAGERS FROM 10 TO 19
Seabra André, Mendonça Denise, Maia José AR, Garganta Rui
Faculty of Sports Science and Physical Education, Portugal
Keywords: physical activity, determinants, parental influence
Introduction
Physical activity and practising sports seem to be the most
important behaviour to promote an active and healthier
lifestyle and to prevent a substantial amount of risk responsible for some chronic diseases. This behaviour is due to an
interaction between someone’s genetic inheritance, family and
schooling, teaching active lifestyles, as well as identify the
influence of some factors upon such relationship.
Aim: To determine parental influence over the levels of their
children physical activity and sports performances, as well as
the influence of other important determinants of this relationship (the family social and economic status, the mother’s age,
the father’s age, their schooling, sex, children’s age, brothers,
friends or even their Physical Education teacher).
Methods
The sample included 5850 children and teenagers, male and
female, from 10 to 19, attending basic and secondary schools,
and their parents. The assessment of physical activity and
sports performances was based on the Baecke et al. (1982)
questionnaire, which enables to estimate the rate of total physical activity, as well as the different types of physical activity
(work/school, sports, leisure). The statistical procedures
included the χ2 test and the multiple regression, The data processing was done by the SPSS 10.0 statistical software.
156
Results and Conclusions
(1) The determinants (the father’s, mother’s age, and their
brother) had no substantial influence over their sports performance; (2) there is a substantial parental influence over teenagers
sports performances, being the father’s influence (χ2 = 97.39;
p=0.000) stronger than the mother’s (χ2 = 85.71; p=0.000);
(3) The male gender is more inclined to practice sports than the
female; (4) Their family’s social and economic status shows a
positive influence over their sports performance.
STUDENTS’ ATTITUDE TOWARDS PHYSICAL EDUCATION CLASSES:
ANALYSIS OF TEACHING UNITS IN VOLLEYBALL AND TRAMPOLINE
Santos Fátima, Graça Amândio
Keywords: physical education, student attitude, program
This study intended to analyse the students’ general disposition towards physical education as a subject area, and the evolution of interest, attitude, perceived competence, and engagement through the teaching units in two regular contents of
physical education programmes, volleyball and trampoline.
Data were gathered from two 9th grade physical education
classes taught by the same teacher (46 students: 28 girls, and
18 boys). A questionnaire adapted from Fonseca (1995) and
Gonçalves (1998) applied for information about students attitudes towards physical education. Changes in students’ interest and perceptions through specific teaching units were measured by a questionnaire adapted from Tjeerdsma et al. (1996).
The assessment tool for students interest’ and attitude in each
class session was adapted from Mackenzie et al. (1994).
Students’ opportunity to respond (number of practice trials,
and rate of successful trials) was observed using event recording procedures.
The analysis is built upon gender and skill level differences.
Group differences, and repeated measures analysis were tested
with nonparametric statistics.
In general, students have a positive attitude towards physical
education. They like this subject area and they acknowledge its
importance, namely for the health and fitness. Boys and girls
valued different aspects for their liking. Boys put more emphasis on competition, and attribute relatively more importance to
physical fitness. They have a higher perceived competence
level, and they considered insufficient the time allocated to
physical education (3X50mn a week). Girls, in contrast, gave
precedence to social aspects and pleasure over competition. A
considerable number of students, mainly girls and low skill
level students, have low self-perceptions of competence at the
beginning of teaching units, and they tend to remain stable
over the units, excepting some increments in volleyball. The
tracking of interest and liking of the activity through the class
sessions portrayed contrasting tendencies, for increment in volleyball and decrement in trampoline. Differences in the opportunity to respond were influenced by gender in trampoline, and
skill level in volleyball.
revista
19.9.03
0:50
Página 157
THE RECOGNITION OF AESTHETICS IN SPORT
BY A POPULATION OF OVER TALENTED YOUNG BOYS
Lacerda Teresa, Cunha e Silva Paulo, Côrte-Real Alda
Keywords: sport, aesthetics, over talented boys
Sport Aesthetics is a recognized domain of study by philosophers of Sport and by Sport Sciences community in general.
However, it is a recent study area that is still in the need of
understanding and knowledge to legitimate its territory. Most
studies proceed from claims and statements of scholar; there is
a lack of information grounded on empirical data. Data proceeding from youth are even scarcer.
The present study aimed to inquire the opinion of young boys
about their image of Sport Aesthetics. It was selected a sample
of 20 boys coming from a regular student population, another
group deriving from an intellectual over talented population
(n=8) and a third one of talented young male gymnasts (n=8).
To collect information the respondents were asked to associate
the classical aesthetic categories beautiful and ugly to a given list
of twenty sports. The sports were representative of the three categories proposed by Kupfer (1988): quantitative, qualitative and
competitive. Statistical handling included Fisher’s Test.
The results enhanced that when intellectual over talented
group is compared with regular students there are statistical
significant differences on the opinion of both groups concerning some sports. In fact regular students considered ugly sports
such as gymnastics, fence, artistic skating and trampolines,
while intellectual over talented boys quoted it as beautiful. The
comparison between talented young gymnasts and regular students made also in evidence differences in gymnastics and
artistic skating: the gymnasts considered it beautiful, while students showed a contrary opinion. There were no significant differences on the confrontation between intellectual over talented group and talented young male gymnasts.
Regular students enhanced a sports aesthetic image that is
against the traditional point of view.
References
Kirk, D. (1984). Physical Education Review 7(1): 65-72
Kupfer, J. (1988a). Sport-The body electric. In William J. Morgan &
Klaus V. Meier (eds.), Philosophic inquiry in sport, pp. 455-475.
Champaign, Illinois: Human Kinetics Publishers, Inc.
Lacerda, T. (2002). Elementos para a construção de uma Estética do
Desporto. Doctoral Thesis, Faculty of Sport Sciences and Physical
A CASE STUDY ABOUT THE PLANNING OF AN OUTSTANDING
YOUTH BASKETBALL COACH
Furriel Ricardo, Pinto Dimas, Graça Amândio
Keywords: planning, basketball, coach
The present study intends to analyze two seasons of coaching
planning from a first rank youth basketball coach. We analyzed
311 sessions of coaching plans referred to 93/94 and 94/95
seasons of a 16-17 years male league basketball coach. The
coach is a well-known and estimated coach among sport community, a major reference among youth basketball coaches.
The coding frame adopted for the analysis of plans was
informed by Marques et al. (2000) category system of training
means and methods, and training load.
Results showed that specific practice was the most used with
40,39% and 41,27% of the total training volume. The coach
used more often specific preparation practice (58, 73% in
93/94, and 59,02%, in 94/95) than general preparation practice
(41,27% and 40,98%, respectively). The game-based methods
represented 37 ,8% and 40, 7% of the total training volume.
The small games with ball are the most used of these methods.
The coach assigned more time to strategy and tactics preparation (58, 75% and 59,02% of the total training volume) than to
technique preparation (37,80% and 37,04%). Physical preparation by itself received little attention (3,48% and 3,94%). In
the tactical preparation, the situation 5x5 is the game form
most used by the coach, representing 18,36% and 18,03% of
the total training volume.
REWRITTEN THE BODY AND SPORTS PRACTICES
— NEW CHALLENGES
Queirós Paula, Botelho Gomes Paula, Silva Paula
Keywords: physical education, body values, new challenges
Introduction
This study is rooted in what is nowadays called the ‘resurgence
of the body’. The questions about the body have acquired
increased visibility and are central topics in the agenda of several social sciences studies. Thus, the body is a prolific object
for an epistemological, anthropological, sociological, and pedagogical analysis, and is a fundamental theme of the current
research. Since physical education practitioners are inescapably
confronted with the body while carrying out their activity, they
have to be aware of the importance the body possesses as a
central category of this same activity. So it is needed to understand the conceptions about the body that the physical education practitioners hold with them. It is our interest, and it is
the purpose of this study to explore the position of the body in
a post-modern time from an axiological perspective, by looking
trough the lenses of discourses (teachers and students) in
physical education, and to try to disclose possible avenues for
physical education in our times.
But even if the body has suffered an increase of attention by
the media and by the cultural analysts, schools, as places of
body construction and constitution, tend to be forgotten.
Physical Education and school sport are key elements of interest to this analysis, but there are subjects that keep on being
laid aside by researchers interests. In an intellectual cultural
context, which has accepted the body as an essentially biological phenomenon (part of an intellectualist tradition of western
157
revista
19.9.03
0:50
Página 158
societies), this omission won’t be so hard to understand after
all. As Kirk (1993) demonstrates, making a sport analysis and
physical activities in literature, one verifies just some references to physical education, which is incredibly surprising,
once we think physical education is an obvious place or ground
to corporality issues to be studied.
As Bento (1999) refers, the fact of being the only subject that
aims preferentially corporality, creating movement possibilities
and avoiding that school became even more intellectualized
and body enemy, it still is a central argument on behalf of
Physical Education presence at school curriculum. Thus,
Physical Education is the subject in which the body establishes
itself as a Pedagogical treatment object. The first impression
that desolates us when we think a little bit about Physical
Education is the fact that we are currently attending a Physical
Education based on a model and on a body understanding submitted to technical rationality, typical of the industrial society
sport, where predominates an unilateral and merely instrumental understanding of the body.
The present times are times of changes, and those changes
resultant of the most general transformations operated in western societies, are equally felt at physical and sportive activities
field, creating some discouragement that begins to be evident,
specially by the several intervening agents in this domain, and
who start to question themselves if the physical and sportive
activities really adjust themselves to the new sensibilities and
expectatives of sport practioners.
Thus, the body must be a concern of Physical Education teachers because it’s in their discipline that it viewed as an object of
pedagogical treatment, and where is revealed the way that the
Educational System understands it. But, which is the role of
the body in Physical Education? What values does it express?
What, in fact, do students and teachers valorise when we ask
them: “what its really important when we talk about the body
values at Physical Education?”
The main goal of this study was to analyse the body from an
axiological perspective, by looking trough the lenses of discourses (teachers and students) in Physical Education.
Methods
Data for this study were collected from 6 schools in Grand
Porto, Portugal. One 9th grade class per school was selected
and the respective Physical Education teacher and students
were interview. In order to inspect the material we have
applied the content analyses technique (to the 12 interviews)
introducing a priori defined categories.
The justification of the categorial system of our study is based
on different body conceptions. Before a theoretical framing previously developed, it was possible to built three big categories
about the body. The first category concerns to the Biological
Body (Mechanical), the second to Expressive Body and the
third category concerns to the social body. For Biological Body
(Mechanical) category, we have considered different dimensions which we’ve referred as sub-categories: body/effectiveness, body /technical-instrumental, body/physical fitness and
body/health. For Expressive Body category we have considered
different dimensions which we’ve referred as sub-categories:
body/aesthetic, body/pleasure and body/way of living experience. For Social Body category we’ve considered different
dimensions which we’ve referred as sub-categories: body/ethic,
body/ecology and body/social construction (Queirós, 2002).
158
Results
The analysis of the material reveals some discrepancy between
teachers and students discourses. In general the
biological/mechanical body category and the ethical category
are paramount in teachers discourses.
The connection of the body to effectiveness appears to us connected with the idea of record, of effort, of overcoming, in conclusion, of achieving better results. In Tinnig’s (1997) perspective this body/effectiveness is one of the vectors of a determined orientation of Physical Education, to which he refers as
“Performance speech” and valorized by teachers who also justify the dominance of the technique by the valorization that the
own programs made of it: “In spite of having several goals, the programs aim the techniques improvement, usually there is techniques
improvement, in spite of having there the goals and the partners
respect, referee respect, teachers respect, … deep down the program is
more techniques, learn the modalities techniques”.
Another aspect to which teachers associate the technique
importance is related to the fact that it constitutes itself as
basis and starting point to the execution and to the possibility
of a game or activities realization that have as basis the technical gesture and that through its domain can increase the motivation for practice. Relatively to technical questions and when
questioned about their importance in Physical Education class,
students expressed that this was one of the most worked
aspects at School. Otherwise lets see: “We spend the majority of
classes time learning those things, it’s technique”.
Relatively to health dimensions the teachers’ opinions are
placed on the physical activities influence, at Physical
Education class in a future perspective, than its importance at
the present.
The issues about the body connection to aesthetic are highly
valued in contemporary society. The aesthetic model of the
proposed (or imposed) body model by society is a young, thin
and beautiful body model (Gervilla, 1997; Kirk, 1997 and
Lipovetsky 1990). But is this category present at school, at
least in the same patterns in which it is presented in society?
Which representation do the teachers do about the body connection to aesthetic in Physical Education? What does their
discourses say? In fact there are few references concerning the
expressive body at all discourses (teachers and students).
A teacher says to us that at school these questions are not
present: “I think it is impossible to connect beauty to the body, it is
impossible”. Relatively to the importance of the body/aesthetic
category at Physical Education classes, students don’t seem to
give it a significant role. The great majority answered negatively when asked: “I don’t think it’s the school duty”.
The elements of pleasure, so highly valued in the literature, are
also values in the discourses of teachers and students, both
sustaining in their particular views the importance of such elements. The hedonist values are a central category in contemporary societies, and are already legitimate values of these societies. The pleasure associated to body dominates certain life
styles, being already an integrant part of today’s societies individuals’ projects. Bento (1999) and Meinberg (1990) also indicate the hedonist values of physical and corporal activities.
In teachers perspective there are several motifs to the pleasure
(or the lack of it) at Physical Education class. Knowing the
importance of this values nowadays (“what they want is physical
activity, they want movement, they want to use the body as they wish,
as they like”), there are teachers who try one way or the other
to meet the students preferred activities, even if they have to
revista
19.9.03
0:50
Página 159
“escape” the established curriculum. When asked about this
category, students showed its importance relatively to hedonist
values, indicating, however, several factors which in their education “clients” perspective contribute to weak satisfaction
rates in Physical Education activities. These students’ opinions
clearly show a difference between what students really want
and what school proposes them or may actually offers. As
Hargreaves (1998) refers, the lack of interest of many students
in the curriculum and the teaching they have, it’s not hard to
understand. Teachers are competing more and more with this
world and its involving culture. The issue of goals and aims
seems to be also determining. At school, students say that
there is no pleasure because there are no goals and aims, or at
least they cannot feel them or identify them. Perhaps the
school goals relatively to physical activities are not the same
ones of the students.
Some teachers recognised some importance in their discourses
to the experiential body category, but students say that those
aspects are not valorised at Physical Education classes. In the
interviews some discourses indicate a concern of the experience of that same body, and of given the student the possibility
of knowing and exploring his/her own body: “it is necessary to
help this kids, so they can develop and know their own body” and “ in
my opinion what is more important in Physical Education, … is that
they will be able to use the body, that they know how to run, that they
know how to kick the ball, how to play with their hands, that they
have the capacity to do all those things, that they want to do it and
that they have pleasure doing it”.
Relatively to the body experiences, perhaps because of fear or
shame, students don’t venture themselves to verbalize.
Not only in the national scenery but also in the international
one, there are authors (Bento 1999; Fernández-Balboa, 1997
and Tinning, 1997) who point out to the importance and relevance of the ethical dimension on the different sceneries of
physical and sportive activities. The ethical category is paramount in teachers discourses: “in my opinion the essential thing in
physical Education is not properly related with the physical part, but
with the ethical one, with the sportive one, because children are in such
a way bombarded with the lack of sportive ethical, with the lack of
sportive spirit… In my opinion, the great battle that teachers of
Physical Education and Physical Education have to do, is to swim
against the stream, and to made them to understand that sport is
something, an activity that has to be healthy, that has to be played
with fair play, with sportive spirit… in my opinion it is essential.”
The ethical values are not completely assumed through students’ speeches. At school as it “is not serious” one do not invest
in these aspects. At the club one already does. The values are
not interiorized, one acts or has ethical behaviors because the
fear of sanctions; as at school the sanctions are not very high
(students say), or at least it does not affect them much, they
put these issues to a secondary plan.
The body as social construction, so important in the current
discourse outside school, does not seem to deserve any relevance within school settings. It is curious to verify that being
an important aspect to be considered by literature, we have
very few references about this subject, and the ones we have
had are from the same persons. We think there isn’t critical
awareness by teachers that makes them feel as reproducers of
social models and possibly hegemonicals. By students we do
not verify any occurrence at verbalization level. It was not possible to us to extract any outlines of speeches that could have
any relation with this matter.
It seems to us that an effort to innovate the general education
and, particularly, the physical education is at stake, which
should lead to a redefinition of its essential goals, of its contents and object, as well as a raising of the quality of the organization ways, of the methods and teaching results, and we
should not forget that the innovation opening is a concept
strongly connected to the professionalism concept, which
means that we are simultaneously in presence of a professionalism question in Physical Education field.
However in Kirk’s (1997) opinion only a radical change of the
School Institution will allow that Physical Education practices
articulate themselves in a more coherent way with the corporal
practices of the other social places. In alternative, Physical
Education and school sport could continue its decline until
being eventually substituted by programs or activities with no
educational value. In the opinion of the same author we are
attending to a true decline of Physical Education and its curriculum practices, which is someway surprising when the body and
the different corporal practices as sport and Physical exercise
are raising its meaning, and a prominent growing in postmodernity times. This actually obligates all the intervenient
agents in these domains to reflect about the subject and to
rethink their intervention ways.The justification for that radicates perhaps in a way of treating the body at schools that continues to construct massive practices of sportive skills and physical fitness without a liberal humanist philosophy of pleasure
development, at a long-term choice and participation. In strictness way Kirk (1997, p.56) says: “Physical Education and school
sport are in decline because they represent a series of modern corporal
practices, concerned in regulate and normalize the children’s body,
through methods and strategies which are perhaps culturally obsolete”.
But which strategies can we use that may contribute to reinvigorate the body at post—modernity? The same author suggests
that if Physical Education programs are to maintain cultural
relevance, they should start by reflecting and contributing more
directly to popular physical culture. However, all this will be
ineffective if at the same time and parallelly the best use of
community resources for schools won’t be done, as well as if
the changes in teachers training and consequently in a strategy,
methodology and contents group to be used by those teachers,
won’t be done.
In this way it is essential for us to understand which values of
physical culture are transmitted by society, which are the one’s
transmitted by School and specifically by Physical Education, in
which way do they adapt or not one from others, finally, to
understand what’s the relation between social corporal practices, outside School, and those who are made at School, specially in Physical Education class. So, it is imperative to rethink
the School Institution in order to allow Physical Education practices to articulate themselves in a more coherent way with corporal practices of the other social places, because it is impossible to separate School activities from its social references and
corporal practices planted in the culture of which it is a part of.
The practices of the teachers concern with the corporal educative possibilities has shown itself as a fructiferous way to
develop their professional activity in a way that reverts into
more rich and fair practices for students. The election of the
contents should open doors and give skills and knowledge, that
are not just to be consumed at School without any possibility
of outside school application (Álvarez& Monge, 1997). It is
needed that in Physical Education and sport it becomes visible
159
revista
19.9.03
0:50
Página 160
the emerging paradigm, already visible in other areas, which is
predominantly holistic and systemic, seeing man in its entireness as a biological and cultural being.
Relating the social aspects with the cultural physical practices
is an important aspect. The fast and dramatic changes in sport
and the body prominence in society have a significative influence on physical activities field. Preparing the Physical
Education teachers for the XXI century requires professional
preparation programs, which are guided for students/clients
diversity, and for a more advanced society. Physical Education
teachers are working in an involving element that will require
reflection capacities in a world of change, and their pedagogical
practices will also have to reflect those complex involvements
(Kirk & MacDonald, 2001).
We have to develop skills to “think beyond square” says Kirk
(1997), reinforcing the need to prepare the new teachers for
today and tomorrow’s teaching at school and to take Physical
Education out of the crisis it is in.
We must rethink the contemporary Physical Education in sense
to becoming corporal richer in all dimensions, in way that boys
and girls can find a more gratifying moments and humanly richer
ones, through new practices and new ways to live their bodies.
References
Álvarez L, Monge A (1997). Persona, Género y Educación:31-71
Bento J (1999). Contextos da Pedagogia do Desporto:19-112
Fernández-Balboa J (1997). Quest, 49: 161-181.
Gervill, E (1997). Postmodernidad Y educación: valores e cultura de
lo jóvenes
Hargreave, A (1998). Os Professores em Tempo de Mudança
Kirk D (1997). Quest, 49: 182-186.
Kirk D, Macdonald D (2001). Quest, 53: 440-456.
Kirk D (1993). The body, schooling and culture
Lipovetsky G (1990). O império do Efémero – A moda e o seu destino
nas Sociedades modernas
Meinberg E (1990). Desporto, Ética, Sociedade :69-76.
Queirós P (2002). O corpo na Educação Física. Leitura axiológica à
luz de práticas e discursos. Doctoral Dissertation. Faculty of Sport
Sciences and Physical Education, University of Porto (not published)
Tinning R. (1997) Critical postmodernism in human movement, physical education, and Sport: 99-120
TEACHERS’ KNOWLEDGE AND BELIEFS ABOUT GENDER
AND SPORT ACTIVITIES
Silva Paula, Botelho Gomes Paula, Graça Amândio
Keywords: gender, teachers’ knowledge
As a social reality, school is composed by “gendered” beings,
meaning that children do not come into school as “tabula rasa”
but already imprinted by experiences and acquirements, and
this reality can not be neglected or disregarded when the
teacher thinks, plans and organises the teaching. The
teacher/educator works with very precise persons not with
abstractions (Patrício, 1990), but on the other hand we must
keep in mind that schools do not exist in a social vacuum -
160
girls and boys start their education with definite ideas about
what is appropriate for their respective gender, ideas which are
reinforced by orthodox sexual divisions in the classroom, in the
playground and on the games field (Hargreaves, 1994).
Either by action or by default, school tends to maintain, reproduce or even reinforce masculine and feminine stereotypes.
Teacher’s sexist attitudes and behaviours are characterised by
their invisibility, and unconsciousness. They are difficult to
change as they are neither lived nor perceived as a problem
(Bonal, 1997).
It is important to know what the teacher does, its basis, how it
is done, and its impact, since the events that occur on the
games field, in the swimming pool or at the gymnasium are
not isolated. The way social relations, namely those of gender,
are structured and consolidated inside the class must be an
issue submitted to the teacher’s analysis, reflection and action.
The teacher’s decision-making and consequent actions or omissions influenced by personal beliefs and knowledge derived from
his/her training as a professional become explicit or implicit
messages which the students perceive within a specific context.
The main goal of this study is to analyse teachers’ knowledge
and beliefs about gender and sport activities. Data for this
study were collected from 10 structured interviews to secondary schools male and female teachers (schools in Grand Porto,
Portugal). In order to inspect the material we have applied the
content analyses technique.
THE CHILD AND THE PHYSICAL EXERCISE
AT THE NINETEEN CENTURY IN PORTUGAL
Ferreira José V, Araújo Carlos, Sardoeira Teresa
Keywords: child, physical exercise, nineteen century
The importance of the physical exercise as development of the
children in the nineteen century wasn’t new, at the time. In the
previous century, some Portuguese writers had already noticed its
importance and tried to convince educators to arrange activities
so that children could practice according to their ages. However,
it was only in the nineteen century that this type of speech make
success to the efforts to acceptance of the physical exercise.
Along the nineteen century, Portugal developed some initiative
to value physical exercise as being essential to the human as a
whole. Despite the clear speech of medical doctors new initiatives began to appear coming from people who intend to promote physical education.
Our aim is to characterize the main ideas supported by the
importance of the physical exercise in that century and the
value of physical education in the same period.
For that, we intend to support our work with texts not only
from the medical community but also from educators, politicians and all the others who make notice of the Gymnastics in
Portugal.
revista
19.9.03
0:50
Página 161
INFLUENCES ON 14-15 YEAR OLD ADOLESCENTS PHYSICAL
ACTIVITY LEVELS RELATED TO PUBLISHED GUIDELINES
Aznar Susana1, Riddoch Chris2
1
2
Faculty of Sports Sciences, University of Castilla La Mancha, Spain
University of Bristol, Bristol, U.K.
Keywords: children, physical activity guidelines, influences
The aims of this study were to assess the proportion of children who achieved the health-related criterion level of 30
preferably 60 minutes of accumulated moderate intensity physical activity per day (Biddle & Sallis, 1998 Young and Active? A
policy symposium on young people and health enhancing physical activity. HEA: London) and to assess the influences upon
it. A sample of 182 boys and 195 girls correctly filled in a physical activity diary for a week and an Environmental and significant others influences on physical activity questionnaire (Aznar
1998, PhD Thesis, Bristol University). Boys were more active
than girls for the total week (Boys: mean: 987.77 min., SD:
477.47; Girls: mean: 832.57 min., SD: 452,98 t= 3.23,
p<0.01), week days (Boys: mean= 631.54 min., SD= 310.6;
Girls: mean= 485.3 min., SD= 296.03, t= 4.68, t<0.01) but
not significantly different for the weekend. 42.9% of boys and
23.1% of girls achieved the guideline. For boys “friends influence” was the only factor that produced a significant function
correctly classifying 67.24% of those boys who achieved the
guideline. For girls “disliking physical activities” produced a
significant function correctly classifying 62.03% of those girls
who achieved the guideline. The fact that socio-environmental
factors are significantly associated with the achievement of
published guidelines may highlight the importance of a social
aspect for boys, and for girls a wider range of physical activities
choices, and perhaps different approaches (e.g. competitive,
recreational and healthy approaches).
COMPARATIVE STUDY OF STUDENTS’ SELF-PERCEPTION,
SATISFACTION IN SPORTS AND ACADEMIC LEARNING
BEHAVIOURS IN THE PHYSICAL EDUCATION LESSONS
AND EXTRA-CURRICULAR SPORTS ACTIVITIES
Rosado António1, Paulos Francisco1, Mesquita Isabel2
1
Faculty of Human Kinetics, Technical University of Lisbon, Portugal
2
Keywords: self-perception, satisfaction on sport, academic learning
behaviours
Introduction
The knowledge about students’ perceptions concerning the
Physical Education lessons and the extra-curricular sports
activities can provide a better understanding of their behaviour
patterns in relation to both settings. From the students’ perceptions it is particularly important to know their self-perception and satisfaction in sports. It makes sense to know if the
levels of self-perception and satisfaction in sports are similar in
both settings as well as the kind of relationship there is
between those variables and the students’ learning behaviours.
There are some studies that show a strong relationship
between self-perception and satisfaction in sports and the
learning behaviours in sports activities (Shigunov, 1991;
Pieron, 1999). Self-perception is positively related with school
achievement and very important related variables (Olszewska,
1982; Wittrock, 1986; Muller et al., 1990; Solmon, 1991).
Pereira (1995) showed that the students with higher selfesteem had a significantly higher academic learning time in the
physical education lessons. Moreover, the students with higher
self-perception with regard to their competence in sports practiced sports activities outside the school and revealed concern
with the development of their physical condition.
Concerning this matter, Piéron (1999) emphasises the influence of self-perception about sports competence on the students’ physical education involvement and on the extra-curricular sports activities. Therefore, perception about sports competence has a significant role in maintaining a high interest
rate both in the physical education lessons and in participating
in competitive sports in and on outside the school.
On other hand, Pereira (1995) verified that the level of student
satisfaction increased just after the physical education lessons.
This study showed the relationship between the level of the satisfaction in sports and motivation to physical education activity.
The aim of the present study was to compare self-perception, satisfaction in sports and academic learning behaviours of the students in the physical education (PE) lessons and extra-curricular
sports activities, namely in team sports. We wanted to analyse if
self-perception, satisfaction in sports and academic learning
behaviours were significantly different in both school settings.
Methods
The participants for this study were middle school students
(n=300), of which one hundred and fifty (n=150) were
involved only in PE lessons and the other one hundred and
fifty (n=150) had complementary extra-curricular sports activities in school. We observed 20 PE lessons and 20 sessions of
extra-curricular sports activities.
We considered one independent variable in two situations (students in Physical Education without extra-curricular sports
activities, and students in Physical Education with extra-curricular sports activities) and different dependent variables: selfperception as a player, self-perception as a student in the physical education lessons, satisfaction in sports, and academic
learning behaviours in physical education lessons and in extracurricular sports activities.
We applied the sports competence scale to evaluate the students’
self-perception, which includes 7 items, and two self-esteem
scales (Pereira, 1995), which include 10 items. Each answer was
put on the Likert Scale with 5 points. Concerning the Harter
Sports Competence Scale (Harter, 1983) we only evaluated the
physical competence component. To evaluate the students’ satisfaction in sports we used the Chelladurai methodology (1984),
composed of 7 items. We studied the consistency in these
scales: the scale about students’ satisfaction in sports showed
one alpha of 0.818; the scale of self-perception one alpha of 0.85,
and the scales of self-esteem as a player, as a physical education
student and in extra-curricular sports activities showed values of
0.85, 0.80 and 0.63, respectively.
In all sessions the students practiced team sports games and
were videotaped. We applied the OBEL-Ulg instrument
(Piéron, 1988) for the systematic observation of academic
161
revista
19.9.03
0:50
Página 162
learning behaviours. This system includes 11 categories (motor
engagement; attention to information; demonstrations; displacements; waiting; off-task behaviours; verbal interactions
and others) which are used to measure the duration of the different behaviour patterns of the students. We observed all the
sessions using an interval recording method (we considered
intervals of three seconds). The reliability was estimated. The
intra-rater percentage of agreement was between 93.2% and
100% and the inter-rater percentage of agreement was between
90.7 and 100%.
For the statistical analysis we used descriptive statistics (mean
and standard deviations) and comparative statistics (Anova
One-Way) after we verified the normality requirements
(Kolmorov-Smirnov test) and the homogeneity of the variances
(Levene test). We also used the Bravais-Pearson Correlation to
analyse the relationship between the different variables. The
reliability of the questionnaires was found with the alpha
Cronbach test, considering the validity of the instruments
applied in other previous studies (Pereira, 1995). For data
analysis we used SPSS 11.0 program.
Results
The results showed that students participating in extra-curricular
sports activities had significantly higher levels of self-perception
(p< 0.001) in comparison to students who practice only curricular physical education, and higher self-perception of sports competence in the physical education lessons (p<0.000).
When we studied the levels of satisfaction in sports we verified
that the students who practice extra-curricular sports activities
showed significantly more positive satisfaction in the practice of
sports (p<0.000) than the students that practice sports only in
the physical education lessons. Nevertheless, in all students the
levels of general satisfaction in sports were positive (3.9 and
4.2, respectively, on the Likert scale with 5 levels).
When we studied the correlations between self-perception as a
player and general satisfaction in sports we verified positive
and significant correlations between both constructs (r=0.32;
p<0.000). The relationship between general satisfaction in
sports and self-perception as a student in the physical education lessons showed the same direction (r=0.45; p<0.000).
On the other hand the students in extra-curricular sports activities had more favourable academic learning behaviours.
Concerning this point, the students attending the extra-curricular sports activities showed higher levels of motor engagement (p<0.00) and paid more attention to the teacher’s information (p<0.04). Contrarily, we observed that the students
that practice only PE lessons, in the other categories like displacements (p<0.04), waiting (p<0.009), and off-task behaviours (p<0.001), revealed higher values than the students
attending the extra-curricular sports activities. Only with
regard to affectivity did they not stand out.
In general, the students of extra-curricular sports activities
showed better levels of self-perception, of satisfaction in sports
and behaviour patterns, as players, more adjusted to learning.
However, we cannot conclude that there is a direct relationship
(cause and effect) between those variables because the present
study is descriptive. It is possible that the option for extra-curricular sports practice is a consequence of higher self-perceptions and higher satisfaction in sports. We cannot exclude the
possibility that extra-curricular sports activities can account for
162
better levels of self-perception, satisfaction in sports (if the
students choose the modality they prefer) and students’ behaviour patterns are more favourable to the learning process. It is
important to carry out research that can clearly define the
nature of the causality in those relationships.
Conclusion
The major conclusion of this study showed a positive response of
the students to extra-curricular sports activities. Indeed, extracurricular sports activities in school proved to have strong value
as a complementary activity to physical education lessons.
References
Baptista, P. (1995). Satisfação com a Imagem Corporal e Auto-estima:
estudo comparativo de adolescentes envolvidas em diferentes níveis de
actividade física. Unpublished Master dissertation, Faculty of Sport
Sciences and Physical Education, University of Coimbra
Chelladurai, P. (1984). Int J Sport Psy, 6, 27-41.
Harter, S. (1983). Development perspectives on the self-system. In, P.
Mussen (Ed). Handbook of Children Development. Vol.IV, N.Y., 275-385.
Muller, J., Gullung, P., & Bocci, V. (1988). Concept de Soi et
Performance Scolaire: Une Méta-Analyse. L´orientation Scolaire et
Professionale, 17, 1, 53-69.
Olszewska, G. (1982). Int J Sport Psy, 13, 2, 107-113.
Pereira, P. (1995). O pensamento e acção do aluno em Educação
Física. Unpublished Master dissertation, Vol. I e II. Lisboa, Faculty of
Human Kinetics, Technical University of Lisbon
Piéron, M. (1988). Enseignement des activités physiques et sportives.
Observation et recherche. Liège : Éditions Université de Liége.
Shigunov, V. (1991). A Relação Pedagógica em Educação Física:
influência dos Comportamentos de Afectividade e Instrução dos
Professores no Grau de Satisfação dos Alunos. Unpublished Doctoral
dissertation, Faculty of Human Kinetics, Technical University of Lisbon
Solmon, M. (1991). Student Thought Processes and Quality of
Practice During Motor Skill Instruction. Unpublished Doctoral
Dissertation. Louisiana State University, Baton Rouge.
Wittrock, M. (1986). Student´s Thoughts Processes. In, M.Wittrock
(Ed.). Handbook of Research on Teaching (3rd ed.). New York:
MacMillan, 297-314
RELATIONS BETWEEN PHYSICAL FITNESS AND HABITUAL
PHYSICAL ACTIVITY LEVELS IN CHILDREN 8 TO 12 YEARS OLD
Baquet Georges1, Guinhouya Comlavi, Andersen Lars Bo2,
Van Praagh Emmanuel3, Berthoin Serge
1
FSSEP, Université de Lille 2, France
Institute for Exercise and Sport Sciences, University of Copenhagen,
Denmark
3 Laboratory of Exercise Physiology, Auvergne University, ClermontFerrand, France
2
Keywords: physical activity, physical fitness, children
Introduction
The aim of this study was to quantify the habitual physical
activity level (HPA) of French prepubertal children during
school and free days, and to analyze the possible relationships
with physical fitness level (PF).
revista
19.9.03
0:50
Página 163
Methods
Thirty-nine children (15 boys et 24 girls), aged 8 to 12 years
old, were involved in this study. They performed five field
tests, some of which comprised in the European physical fitness test battery (EUROFIT)1. The selected tests were standing
broad jump (SBJ in cm), 10*5 meter shuttle run (SHR in s),
sit-and-reach (SAR in cm), the number of sit-ups in 30 seconds
(SUP) and 20- meter shuttle run (20MST in km.h-1). Children
HPA was recorded during a 7-day period, with an uniaxial
accelerometer (Computer Science Applications Inc (CSA),
model 7164, Shalimar, FL). The epoch duration was set to 1
min between 7 am and 9 pm and the time spent above a HPA
threshold, corresponding to moderate to vigorous intensity (>
3 Mets) (MVPA time), was calculated2.
Results
There was no significant difference between boys and girls, in
anthropometric measurements, performances in SBJ, SHR, and
SUP, and in HPA and MVPA time, for school days, as for free
days. Nevertheless, HPA (counts.min-1) and MVPA time
(min.day-1) were significantly higher (respectively, p<0.001 et
p<0.01) during school days than free days. Significant relationships (p<0.001) between HPA and MVPA time were observed,
for school days (r=0.82) and free days (r=0,89). In addition,
56% of the children participated in MVPA activities for at least
half an hour per day3. Only relationships between SBJ and
MVPA time (r=0.36, p<0.05) during school days, and between
body mass index and MVPA time (r=0.34, p<0.05), during
free days, were found.
Conclusion
In children, the habitual physical activity level is significantly
higher during school days, but was not related to the different
components of physical fitness. It should be interesting to
increase HPA during school days, notably in PE sessions, and
observe the influence of such an improvement and its intensity
on the habitual physical activity.
References
1. Commitee of Experts on Sports Research (1988). Handbook for the
Eurofit tests of physical fitness. Rome: Edigraf Editoriale Grafica, 30: 58
2. Freedson PS, Melanson E and J Sirard (1998). Med. Sci. Sports
Exerc. 30: 777-81
3. Biddle S, Sallis J, Cavill N. (1998). Policy framework for young
people and health-enhancing physical activity. In: Biddle S, Sallis J,
Cavill N, editors. Young and Active? Young people and health-enhancing physical activity: evidence and implications. London: Health
Education Authority, 3-16
TRAINING PERIODIZATION IN MIDDLE AND LONG DISTANCE
RUNNING. EMPIRICAL AND COMPARATIVE STUDY BETWEEN
PERIODIZATION MODELS OF BEST PORTUGUESE SENIOR ATHLETES WHEN YOUNGSTERS AND THE CURRENT YOUNG ATHLETES
Keywords: middle and long distance running, periodization,
young athletes
Introduction
In athletics and high competition, coaches and athletes are
always searching for the best training system and the best periodization. However, the importance of training periodization
has differentiated profiles, when it deals with children, young,
or adult athletes. In adults, the training periodization is overwhelmed by competitive and economic reasons, a factor which
may not occur in children and young athletes training. In these
cases, it is claimed that periodization, when necessary, should
be submitted to formative and educational values. Additionally,
research on this subject is very scarce and we don’t know what
occurs in the practice of youngsters’ training in Portugal.
Therefore, we want to observe and compare the past [using a
sample of success former athletes in middle and long distances
running (MLD)] and the present (using a sample of MLD
young athletes) training process, relating to periodization.
Method
The research was carried out with two independent samples of
individuals: – sample A - 32 coaches who fit 84 young talented
athletes (with ages between 10 and 19 years old) in MLD; and–
sample B - circumscribed to 26 former elite athletes of both
sexes that had participated in European and/or World
Championships and/or Olympic Games (MLD events).
Two open reply interviews, specially made and validated for
these samples were used. All the collected information (samples A and B) was examined using content analysis techniques.
In sample B the collected information referred to the athletes
past athletic lives, while young.
Results
The main obtained results were: (i) at stage of initial specialisation, the duration of the transition period was 32±16,5 days
(7-63) for individuals of sample A and 79,5±26 days (31-122)
for the athletes of sample B; (ii) at stage of deep specialisation,
the duration of the transition period was 30,5±30,7 days (763) for actual youngsters and 50,4±30,7 days (0-122) for former success athletes; (iii) in sample A athletes, the duration of
the transition period from one stage of preparation to another
does not disclose statistically significant differences. The
results show that the training periodization guided by formative principles is not part of the coaches concerns (for sample
A), and that it follows (in all the preparation stages studied)
the logic of income and importance of the competitive events
and competition calendars.
MOTOR PERFORMANCE AND MATURATIONAL STATUS.
STUDY IN CHILDREN OF TWO DIFFERENT SCHOOL
ENVIRONMENTS (RURAL AND URBAN)
Moreno Duarte, Vasconcelos Olga
Rolim Ramiro, Marques António T, Maia José AR, Colaço Paulo,
Conceição Filipe
Keywords: motor performance, rural and urban environments, children
and adolescents
163
revista
19.9.03
0:50
Página 164
Introduction
The study of the physical fitness of the populations has congregated, in the last decades, a growing interest for recognizing it’s
association to physical activity routines, and the influence on
the subject’s adaptation to the continuous solicitation of daily
tasks (Malina, 1991). Physical activity assumes more and more
relevance in the well being and quality of life of individuals. For
the child, it is also a way to acquire several knowledge and abilities, either motor or cognitive. Furthermore, physical activity is
a good way of socializing and developing self-concept and selfesteem (Holopainen, 1986). Since childhood, it’s fundamental
to promote a regular physical activity instead of a sedentary
lifestyle, which contributes to the appearing of several diseases
of different ethiology since childhood, and the loss of quality of
life (Astrand, 1992). According to Malina (1980), children’s
motor activities constitute the foundation of their motor proficiency. The more diversified the motor experiences in childhood, the more successful will the young and the adult be in
their habitual physical activity and in their motor performance.
There are several examples in the literature suggesting that
children spend a lot of their free time in sedentary activities
(Cale, 1991, in Gomes, 1996). This author also defends that
the level of regular physical activity presents a tendency to
decrease with age, mainly when the adult did not consolidate
an active and healthy lifestyle, during childhood or in adolescence. In the last 20 years we assisted to the rising of studies
which systematically investigate the relationships between biological, psychosocial and cultural events that mark adolescence.
Despite that all of us recognize social life as a determinant factor in human development, there are few studies concerning
the influence of different cultural contexts in the adolescent’s
lifestyle and regular physical activity. These studies (e.g.
Malina, 1980) suggest, however, that the social, cultural and
economic environment where the behaviour occurs is decisive
in the individuals’ lifestyle and regular physical activity. Social
context concerns the interactions with the family, with others
and with organizations. Cultural context comprises the cumulative weight of those interactions along generations, representing values and traditions associated to behaviour. The interactive effect of decisive factors as growth, maturation and the
environment, turn physical fitness into a very “plastic” subject,
of great variation among populations (Freitas, 2001).
The aim of this study is to evaluate the level of motor performance of children and adolescents living in different contexts (a
rural area and an urban area), according to sex and maturational status.
Methodology
The sample comprises 204 subjects of both sexes, aged 11-15
years old, belonging to different contexts: one group (n=100)
from an urban area (Matosinhos), and the other one (n=104)
from a rural area (Trás-os-Montes). All subjects were drawn
from the public school nearer to their home, and all of them
belong to low or average socio-economic status. To assess motor
performance the EUROFIT Battery (1988; 1993) was used.
However, the test of endurance has been taken from the
FACDEX Battery (1992). Two different inquiries were used in
order to evaluate the maturational status: one of them, applied
to the girls, was the menarcheal age (concerning the retrospective method) and the other, applied to the boys, was the genital
development (using the Tanner Method, 1962). Statistical procedures involved descriptive statistics, the ANOVA Factorial,
164
Pearson’s product moment correlation coefficient (r) and the
contingency tables. Concerning the nonparametric statistics, the
Chi-squared test was used. The significance level was set on 5%.
Results
The results suggest a superiority of physical fitness levels in
children and adolescents of both sexes of the rural environment,
when compared to their counterparts of the urban environment.
We observed significant statistical differences in the tests of
hand grip (p=0.024) and shuttle run (p=0.000). (Table 1).
Table 1: Physical fitness. Comparison between rural environment
and urban environment. Mean, standard deviation, t and p values.
When we compared the results obtained with the boys, we verified that the boys’ level of physical fitness is higher in the
rural environment than in the urban areas. However, only the
shuttle run test presented a significant statistical difference
(p=0.000) (Table 2).
Table 2: Boys. Physical fitness. Comparison between rural
and urban environments. Mean, standard deviation, t and p values.
Concerning the girls, we also verified higher levels of physical
fitness in the rural environment, with significant statistical differences in the shuttle run (p=0.035) and manual dynamometry (p=0.000) tests (Table 3).
Table 3: Girls. Physical fitness. Comparison between rural
and urban environments. Mean, standard deviation, t and p values.
revista
19.9.03
0:50
Página 165
Concerning the physical fitness variation according to maturational status, results indicate that globally, boys evidence an
improvement of the results along the maturational categories,
namely in the following components: static strength (Hand
Grip), explosive strength (Standing Broad Jump), flexibility (Sit
and Reach), agility and running speed (Shuttle run 10x5) and
cardio-vascular endurance (Endurance 12’). (Fig. 1)
Fig. 1: Boys. Physical fitness according the maturational status
(genital development).
Our results support the studies from other authors (e.g. Pineau
et al., 1988; Jones et al., 2000) that found an important effect
of sexual maturation in boys’ physical fitness expression.
With respect to girls, our results suggest a physical fitness level
improvement along the maturational development (age of
menarche). Pos-menarcheal girls present superior physical fitness levels in almost tests when compared to their counterparts (Fig. 2).
Fig. 2: Girls. Physical fitness according the maturational status
(age of menarche).
Discussion
Comparing rural and urban environments, the results suggest
that the differences observed between the groups can be related
with the variety of incentives that children in the rural area have,
as well as the variability of their practice. They play games and
make movements evolving more strength and speed than their
counterparts of the urban area. They have more mobility and
more freedom to manipulate different objects, to climb obstacles, to catch, to pull, to run, to pursue, to jump, as well as
wider spaces to accomplish all of these actions and movements.
Several authors (e.g. Bragada, 1995; Freitas, 2001) have been
elaborating studies that suggest a physical fitness superiority of
the infantile and juvenile populations of the rural environments.
Concerning the comparison between both environments in
each sex, our results, support those observed in the study of
Bragada (1995). This author, with a group of 9 and 10 years
old girls from Trás-os-Montes, verified a statistically significant
superiority of the rural environment in the test of manual
dynamometry. However, in the shuttle-run test, Pissarra (1993)
observed a statistically significant superiority in the 8 and 9
years old girls from the urban environment.
In general, we can say that there is a tendency to verify a superiority of physical fitness levels in girls and boys of the rural
environments (e.g. Pissarra, 1993; Bragada, 1995).
Our results support the investigations undertaken from other
authors (e.g. Pineau et al., 1988; Jones et al., 2000), that found
an important effect of the sexual maturation in the boys’ physical fitness expression.
Malina & Bouchard, (1991) emphasize that the physical fitness
development is dependent to the rhythm of maturation. They
suggest that we should take in account that this rhythm is not
uniform and it can present important variations in each subject
and across subjects.
Conclusions
The main conclusions are as follows: (i) The children and
youth living in the rural area (taking both sexes into account)
showed higher levels of motor performance than those living in
the urban area; (ii) Significant differences have been observed
in the tests of manual dynamometry (manual strength), as well
as in the shuttle run (agility).
References
Astrand P (1992). Medicine and Sciences in Sports and Exercise, 24,
2, 153-162
Bragada J (1995). Influência do Tempo Diário de Actividade Física na
Aptidão Física de Crianças do Sexo Feminino de 9-10 anos
Provenientes de Meios Diferentes (Rural e Urbano). Unpublished master dissertation, FCDEF - UP.
EUROFIT (1988). Handbook for the Eurofit Test of Physical Fitness.
Council of Europe.
EUROFIT (1993). Test Européen d’Aptitude Physique. Conseil de
l’Europe. Deuxiéme Edition.
Freitas D (2001). Crescimento somático, maturação biológica, aptidão
física, actividade física, e estatuto sócio-económico de crianças e adolescentes madeirenses. O estudo de crescimento da Madeira. Unpublished
doctoral dissertation, FCDEF - UP.
Gomes P (1996). Coordenação motora, aptidão física e variáveis do
envolvimento. Estudo em crianças do 1º Ciclo de Ensino de duas
freguesias do Concelho de Matosinhos. Unpublished doctoral dissertation, FCDEF - UP.
Holopainen S (1986). Reports of Physical Culture and Health, 53:77-95.
165
revista
19.9.03
0:50
Página 166
Jones H et al (2000). Annals of Human Biology, 27 (1 Suppl): 57-65.
Malina R (1980). Environmentally related correlates of motor development and performance during infancy and childhood. In C Corbin (ed).
A Textbook of Motor Development (2ª ed).
Malina R (1991). Darwiniam Fitness, Physical Fitness and Physical
Activity. In: GK. Mascie-Taylor (eds). Applications of Biological
Anthropology to Human Affairs.
Malina R, Bouchard C (1991). Growth, Maturation and Physical
Activity
Pineau JC et al (1988). Cinésiologie, XXVII: 209-215.
Pissarra MS (1993). Desenvolvimento Motor e Envolvimento Social.
Estudo do Crescimento e Desenvolvimento das Capacidades Motoras em
Crianças dos 7 aos 9 Anos de Idade nos Meios Rural e Urbano.
Unpublished master dissertation, FMH/UTL.
Tanner, J (1962). Growth at adolescence (2nd ed.)
MOTOR COORDINATION AND BODY IMAGE PERCEPTION.
COMPARATIVE STUDY IN GIFTED AND NON-GIFTED BOYS
Oliveira Ana, Silva Adília, Vasconcelos Olga
Keywords: gifted children, body image, motor coordination
Introduction
“I don’t have special gifts, but I am extremely curious” (Albert
Einstein). Everybody recognize that understanding the extraordinary levels of the human mind is important for our society
and for the scientific knowledge of human potential. The scientific investigation about the gifted people already remounts to
the reports of Galton (1869). These reports concern the genetic
and statistical researches on gifted children, being the first
quantitative studies about human abilities. According to this
investigator, subjects with the ability of outstanding accomplishment possess a larger amount of specific aptitudes.
However, he verified that those qualities, although they are the
same ones that others possess, they exist in a larger amount in
gifted people.
Oliveira & Oliveira (1999) consider that the main impulse to
enlarge the interest for studying gifted people came from the
important study of Terman (1926). This investigator followed
longitudinally 1500 gifted subjects since 1921, from primary
and secondary school, and accompanied them up to 1955. The
results of this investigation allowed to understand gifted subjects under several perspectives: physical and mental health,
school success, personality, outside school interests, social origin, attitude towards life and professional success. The most
important characteristic was a high IQ, and this aspect became
the criterion used for identification of gifted children.
Cortizas (1999) suggests that gifted people possess the following characteristics: (i) IQ higher than 130 (understood as a
group of abilities, talents or mental abilities); (ii) speed of
learning; (iii) special abilities on processing information, using
it and making decisions; (iv) great creativity; (v) great motivation and interests.
However, the social isolation reported in gifted children can
have reflexes in their motor and perceptive development,
including the areas of motor coordination and body image per-
166
ception (Almeida et al., 1999).
Body image is a dynamic concept, which may be defined in
terms of a picture or a mental representation of the body-self
that gradually changes throughout life as the body develops
and changes (Collins, 1981). Phenomenal body size is defined
as the experienced or estimated size of body parts (Kreitler &
Kreitler, 1988), and is one of the most characteristic aspects of
the body image (Schilder, 1968), playing an important role in
perception (Vasconcelos, 1995), in development (Cratty, 1986)
and personality (Kreitler & Kreitler, 1988).
Regular engagement in physical activity appears to have both
physical and mental benefits, including a better evaluation of
one’s body image accuracy and the development of a more positive body image satisfaction. These aspects of body image
seem also to suffer alterations across the growth process, with
emphasis during the pubertal period.
Perceptions of body parts and their functional abilities, the
relationship of one’s body in space, and the ability to regulate
movement in space, all provide valuable feedback information
about the image one has of one’s body.
Several efforts have been done to study the relationship
between ability in physical activities and sports and the development of positive feelings and beliefs about the self, including
self-image and body image (e.g. Davis & Cowles, 1991).
Berger et al. (1997) accomplished studies with children aged 8
to 12, pretending to analyze the variation of motor coordination
according to the levels of body image perception. The authors
verified that children with higher body image perception accuracy levels presented higher levels of motor coordination.
The aim of this study is to investigate body image perception,
motor coordination and the relationship between these two
factors, in the gifted male and in the non-gifted male aged
between 8 and 11 years old.
Methods
The sample comprises five gifted male and five non-gifted
male aged between 8 and 11 years old. None of these children
are athletes or present a special talent to physical activity or
sports. Both groups have physical education classes twice a
week (120 minutes).
The assessment instruments used in this study were the Body
Size Estimation Method (BSEM), from Kreitler & Kreitler
(1988) and the Körperkoordination Test für Kinder (KTK),
from Schilling & Kiphard (1976). The first one consist of asking the subject to estimate, in a random order, the size of ten
body parts: his height, width of the mouth, the shoulders, the
waist and the hips, the length of the hand, the face, the ear and
the nose, and the height of the forehead. The size estimations
were preceded by the following instructions: with the aid of
your hands or fingers you can show the size of various things.
For instance, by bringing your hands nearer to each other you
can show smaller sizes or distances and by spreading them further apart you can show bigger sizes. Your task will be to show
the size of some of your body parts or aspects. All estimations
were done in the standing position, with the eyes closed so as
to enable a better representation of inner sensations and prevent distraction and comparison with external objects or even
with the estimated body part. Because keeping the eyes closed
for a longer period might create special effects that would
influence the later estimations more than the initial ones, the
subject was permitted to open his or her eyes between estimations (Kreitler & Kreitler, 1988).
revista
19.9.03
0:50
Página 167
To calculate the percentage difference scores, BPI (Body
Perception Index) = (perceived body size/real body size) x 100
was applied. A value equal to 100 represents 100% accuracy. A
value above 100 represents an overestimation, and a value bellow 100 represents an underestimation of body parts size (Ruff
& Barrios, 1986). Test-retest reliability for the size estimations
was checked over a two-week interval in 90 male and female
subjects, ranging from 4 to 30 years old. The mean correlations
across all estimations, in all groups, were in the range of .93 to
.97 (Kreitler & Kreitler, 1988).
The second assessment is a body coordination test for children.
It comprises the following tests: Backward Balance, Single Foot
Jump, Sidestep Jump and Lateral Transposition.
The statistical procedures used were: mean, standard deviation,
minimum and maximum values, Mann Whitney test and
Pearson’s correlation coefficient. Alpha level was set at p≤ .05.
Results
Table 3: Motor coordination (KTK tests) in gifted and non-gifted
children. Mean, standard deviation, z and p values.
Table 3 shows a significant difference between gifted and nongifted children in the Lateral Transposition test. Gifted children
presented better performance in the Backward Balance (3cm;
4,5cm) and in the Sidestep Jump (1st attempt) tests. Non-gifted
children presented better performance in the other tests.
* p ≤ 0.05
** p ≤ 0.01
Table 4: Gifted children. Correlations between Motor Coordination
and Body Image Perception Index.
Table 4 shows a significant positive correlation between Height
Body Perception Index and Single Foot Jump.
Table 1: Means, Std. Dev., minimum and maximum values of raw
difference scores of body size estimations for each body part.
The majority of phenomenal body size estimations presented
deviations from the actual body size of the estimated body
parts, the mean deviation in terms of raw difference scores
being 4,30 cm ± 0,73 cm (range: 3,33 cm – 5,88 cm).
* p ≤ 0.05
** p ≤ 0.01
Table 5: Non-gifted children. Correlations between Motor Coordination
and Body Image Perception Index.
Table 5 presents significant positive correlations between
Bodily parts Body Perception Index and Sidestep Jump,
between Body Perception Index (mean values) and Single Foot
Jump and between Body Perception Index (mean values) and
Sidestep Jump.
Table 2: BPI (Body Perception Index) of bodily and facial parts in gifted and non-gifted children. Mean, standard deviation, z and p values.
There is a statistically significant difference between both
groups, focused on Body Perception Index of the face.
The percentage difference scores varied significantly for the
various assessed parts in each group. Percentage difference
scores are larger for facial than for bodily parts.
Discussion
Body image perception. Results presented a significant statistical
difference between gifted and non-gifted children on face length
perception. Considering these results we can suggest, like
Katchadourian (1977), that the behaviour alterations verified in
the beginning of the pubertal period leads the subjects to spend
many time in front of the mirror. Gifted children possess different interests and motivations, which brings them to spend fewer
hours than the non-gifted children looking at the mirror.
167
revista
19.9.03
0:50
Página 168
Motor coordination. Results presented a significant statistical difference between gifted and non-gifted children on the lateral
transposition test. We can suggest that non-gifted children
spend more time playing games and having a larger variety of
motor experiences than their counterparts. Malina (1984) and
Krombholz (1997) did not observe significant differences in
children of the same age. This observation led us to suppose
that the differences we observed are resultant from the different characteristics of each group.
Body image perception and Motor coordination. Melo (1998) verified
negative correlations (to higher values of body image perception correspond smaller values of motor coordination) and positive correlations (to higher values body image perception correspond higher values of motor coordination) in her comparative study of body image perception and motor coordination, on
children between 7 to 10 years old. The existence of negative
correlations between body image perception and motor coordination had been observed by several authors, such as
Schoemaker - Kalverboer (1994, cit. Berger et al. 1997). The
author compared groups of children with different levels of
motor coordination, verifying that children with weak coordination presented more difficulties to percept their bodies. These
children also manifested smaller levels of social competence.
Conclusions
The conclusions of our study were:
According body image perception: (i) Body image perception differs between gifted and non-gifted children; (ii) Non-gifted children presented higher levels of body image perception than their
counterparts, (iii) Both groups overestimated their body image.
According to motor coordination: (i) Motor coordination differs between gifted and non-gifted children; (ii) Non-gifted
children presented higher levels of motor coordination than
gifted children.
According the relationship between body image perception and
motor coordination: (i) There is an association between these
two factors. However, this association is different in each group.
References
Almeida L, Oliveira E, Melo A (1999). Alunos sobredotados:
Contributos para a sua identificação e apoio
Berger BG, Larkin D, Rose B (1997). Adapted Physical Activity
Quarterly, 14:210-221
Collins JK (1981). J. of Youth and Adolescence, 10, 3:243-254
Cortizas MJ (1999). Alunos sobredotados: Contributos para a sua
identificação e apoio
Cratty B (1986). Perceptual and motor development in infants and
children (3ª ed.)
Davis C, Cowles M (1991). Sex Roles, 25, 1/2: 33-44
Galton F (1869). Hereditary genios
Katchadourian H (1977). The Biology of Adolescence
Kreitler S, Kreitler H (1988). Genetic, Social and General Psychology
Monographs, 114:7-32
Krombholz H (1997). Perceptual and Motor Skills, 84:1168-1170
Malina RM (1984). Advances in Pediatric Sport Science
Melo D (1998). Imagem Corporal e a Coordenação Motora – Estudo
Comparativo em crianças dos 7 aos 10 anos. Unpublished master dissertation, FCDEF - UP.
Oliveira JH, Oliveira AM (1999). Sobredotação e Criatividade
Ruff GA, Barrios A (1986). Behavioural Assessment, Vol.XVIII:237-252
Schilder P (1968). L’Image du Corps. Étude des Forces Constructives
168
de la Psyché. (2nd ed.)
Schilling F, Kiphard E (1976). J. of Physical Education and
Recreation, 47 (37):37
Terman LM (1926). Genetic: Studies of genius: Mental and physical
traits of thousand gifted children
Vasconcelos O (1995). A imagem corporal no período peripubertário.
Comparação de três grupos étnicos numa perspectiva biocultural.
Unpublished doctoral dissertation, FCDEF - UP.
ENERGY EXPENDITURE OF SEDENTARY ACTIVITIES IN YOUTH
Pearce Patricia F1, Harrell Joanne S1, McMurray Robert G2,
Pennell Michael3
1
School of Nursing, 2 Department of Exercise & Sport Science,
School of Public Health
University of North Carolina at Chapel Hill, Chapel Hill,
North Carolina, USA
3
Keywords: sedentary activities, leisure activities, energy expenditure
Introduction
Although investigation of moderate and vigorous activities is a
primary focus of much research, increasing sedentariness among
children and youth is reported and there is a documented need
to understand more about the energy expenditure of sedentary
activities (Marshall et al., 2002). A highly sedentary lifestyle is
considered a major contributing factor to non-communicable diseases (e.g., heart disease, type-2 diabetes, and some cancers) in
many countries. With increasingly sedentary lifestyles comes a
parallel growing burden in terms of personal, social, and overall
economic burden, thus there is a global concern regarding the
prevalence of a sedentary lifestyle (World Health Organization:
55th World Health Assembly, Mar 27, 2002).
Inactivity has been shown to start as early as 8 years of age and
inactivity is more likely than a highly active lifestyle to track, or
persist into adulthood (Kimm et al., 2002). Further, when large
amounts of time are spent in sedentary pursuits, there is less
time for more vigorous activities (Marshall et al., 2002).
Increased sedentariness is documented in everyday leisure activities, as well as in school, where children spend a preponderance of their time: A large national study demonstrates an
average of only about 25 minutes of moderate to vigorous PA
per week in PE classes per week, well under the Healthy People
2010 goals for frequency and intensity of PA (The National
Institute of Child Health and Human Development Study of
Early Child Care and Youth Development Network, 2003). In
the Cardiovascular Health in Children and Youth (CHIC) study,
homework, reading, video games, and TV watching were among
the most common activities reported in children and youth ages
8-17 (Bradley et al., 2000). Of these common childhood activities, TV watching has been studied most often. Reports of time
spent watching TV vary from as little as 1 or 2 hours a day
(Hernandez et al., 1999;Lindquist et al., 1999), which is similar
to the 5 to 15 hours per week reported by Robinson (1999), to
a report of 23 hours/week (Faith et al., 2001).
If we can understand more precisely the energy expenditure of
activities considered sedentary and in which children participate
regularly, we can gain a more complete understanding of sedentariness. An improved understanding of sedentary activities in
revista
19.9.03
0:50
Página 169
children can aid in the development of interventions for reallocation of sedentary activities to a higher level of energy expenditure. Reallocation of even small numbers of activities to those
that expend more energy can support increases in overall energy
expenditure (Blair et al., 1992;Marshall et al., 2002). In adults,
TV viewing is estimated to be at the same energy expenditure
as rest, with a MET of 1.0 (Ainsworth et al., 2000). But is this
true for children and adolescents? Energy expenditure (EE) for
sedentary activities in children and youth is primarily based on
estimates. More precise measurement of these activities is
needed to understand the contribution of sedentary activities to
total energy expenditure, as well as to provide a more informed
base for intervention development.
The primary purpose of the Energy Expenditure of Physical
Activity in Youth Study (EEPAY) was to determine energy
expenditure in terms of oxygen uptake, caloric cost, and metabolic equivalent (MET) level of activities common to children
and adolescents (ages 8-18), to evaluate the differences by age
and gender, and to compare results with published METs of the
Compendium (Ainsworth et al., 2000). This presentation gives
data from a subset of the activities measured in the EEPAY
study. The purpose is to evaluate energy expenditure of common sedentary activities and to determine if VO2 differences of
sedentary activity are (a) significantly different from energy
expenditure at rest, or (b) if they differ by gender. The activities examined are TV viewing, video games (while seated and
while standing), reading, planning a board game, and taking a
computerized math test.
Subjects were familiarized with the portable metabolic system
and instructed in all procedures and activities by trained
research assistants. Data were collected breath-by-breath and
later were averaged over the data collection period to provide
the mean VO2 for each activity. One of the investigators (RGM)
reviewed the graphic print-outs of the data for all subjects to
eliminate artefacts and assure that steady state was reached for
all activities. To further assure steady state, the first two minutes and last minute of data for each activity were excluded.
Thus data were analyzed for 7 minutes of each activity.
Analyses included descriptive statistics for demographic data,
ANOVAs to determine age and gender differences, paired t-test,
and two-sample t-tests for assessment of gender differences.
Because of VO2 similarities across ages, overall age groups were
identified and results are provided for age-group rather than for
each age. The age groups varied slightly for boys and girls,
most likely because girls reach physical maturity at an earlier
age and boys. For girls, group 1 = 8-11 years; group 2 = 12-14
years; group 3, 15-18 years. For boys, group 1 = 8-12 years;
group 2 = 13-15 years; and group 3 = 16-18 years.
Results
The results are shown overall, with boys and girls combined, in
Table 1. VO2 differed significantly across age groups for all
activities (p<0.0001 from one-way ANOVA). A post hoc test
(Student-Newman-Kuels) showed that VO2 decreased significantly (p<.05) with increasing age group (see Table 1).
Table 1: Mean VO2 (ml/kg/min) for each Age Group
Methods
All procedures were approved by a multiple assurance Internal
Review Board. Written informed parental consent and child
assent were completed by all participants. Measurements were
performed at the Applied Physiology Laboratory at the
University of North Carolina. The study involved 317 children
and youth, ages 8-18, with at least 10 subjects of each age and
gender; that is, there were at least 10 boys and 10 girls who
were aged, 8, aged 9, etc. Overall, 47% of the subjects were
female and 53% male.
Self-administered questionnaires were used for age, sex, and
racial affiliation and the Pubertal Development Scale (PDS)
was used to determine self-reported pubertal status. The PDS
is a scale that is widely used for determination of pubertal status and has been validated with physician-based ratings of
pubertal development (Petersen et al., 1988), by interview
assessments of maturity (Brooks-Gunn et al., 1987) and with
self-reports using picture comparisons (Petersen et al., 1988).
Internal consistency reliability of the PDS ranges from a
Cronbach alpha of 0.68 to 0.83 (Brooks-Gunn et al.,
1987;Petersen et al., 1988).
We measured oxygen uptake (VO2) with a portable metabolic
system (COSMED K4b2), which is documented to accurately
measure energy expenditure (McLaughlin et al., 2001).
Consistency for breath, CO2 and O2 were established.
Measurements were taken at rest, and during 6 sedentary activities: board games, math test, self-selected homework or reading,
a computer-adaptive math test, watching TV, and two types of
non-violent video games (a seated Nintendo game and arcade
style video games, completed while standing). Each of the activities was performed for 10 minutes, with a 5 minute break
between the activities. The activities were done in the same
manner by all subjects, following a carefully designed protocol.
As shown in Table 2, there were some differences in EE by
gender. VO2 was slightly, but non- significantly greater in
males for all but one activity. When using a Bonferroni correction for multiple analyses, the only significant difference by
gender was for VO2 during standing video games, which was
higher for boys (7.5 ml/kg/min, sd ±2.3) than girls
(6.6ml/kg/min sd ±2.4).
169
revista
19.9.03
0:50
Página 170
Table 2: Mean VO2 (ml/kg/min) for each Gender
Because most values were very similar by gender, we looked at
the difference between EE at rest and EE during each of the 6
sedentary activities. After Bonferroni correction, all sedentary
activities except TV were slightly, but significantly greater than
EE at rest (see Table 3). The EE during TV watching
(ml/kg/min: girls 5.0 ±1.5; boys 5.3 ±1.5) was essentially the
same as that during rest (ml/kg/min: girls 4.9 ±1.5; boys 5.1
±1.4). On average, subjects expended the most energy while
playing arcade video games and board games (see Table 3).
Table 3: Difference between energy expenditure
during a sedentary activity and that of resting
In addition we examined the METs for these sedentary activities by dividing the EE of each subject during these activities
by his or her EE at rest, on a gender specific basis. For both
genders there were no significant differences in METs for most
activities: MET was 1.3 for board games, 1.2 for the math test,
1.1 for reading, 1.0 for TV watching, and 1.2 for sitting video
games. There was a gender difference in METs during standing
video games (MET was 1.4 for girls and 1.5 for boys).
Discussion
The results of this study indicate there are minor differences in
EE across sedentary activities, with significant difference across
age groups for arcade and video games for each activity. For
both arcade and video games, a significant decrease in VO2
with increasing age group is demonstrated. The EE during TV
watching is very similar to the EE during rest, confirming related findings regarding the low level of energy expenditure related to TV watching (Klesges et al., 1993). Thus, selective
reduction of TV watching may be a promising intervention
component to increase EE, even if replaced only with other
sedentary activities of a slightly higher EE level.
170
On average, subjects expended more energy while playing arcade
video games and board games than while resting (2.1 and 1.4
ml/kg/min more energy respectively), with males expending
more energy while playing arcade games than females, although
the gender difference is not statistically significant. Although
small differences, this finding underscores the importance of
conceptualizing TV viewing separately from videogames or computer activity. There is documentation of significantly different
amounts of time spent in these activities among children and
youth (Hernandez et al., 1999). The findings that board games
use a little more energy than similar sedentary activities may be
related to the fact that these were competitive games, played by
the child with one of the research assistants.
Although it is recommended that all children and youth participate in moderate to vigorous activities on a regular basis to
establish a healthy lifestyle, a documented rise in a sedentary
lifestyle mandates better understanding of sedentary activities.
These data further understanding of 6 sedentary activities of
children and youth. If precise information regarding EE is
needed, these measurements can be used. Understanding the
energy expenditure of sedentary activities is essential to fully
understand overall energy expenditure and to better inform
timely, targeted, and pertinent behavioral interventions.
Further investigation is needed to understand the contribution
of sedentary activities of children and youth to overall energy
expenditure and to investigate the possibility of reallocation of
sedentary activities to less sedentary.
References
Ainsworth BE, Haskell WL, Whitt MC, Irwin ML, Swartz AM, Strath
SJ, O’Brien WL, Bassett DR Jr, Schmitz KH, Emplaincourt PO, Jacobs
DR Jr and Leon AS (2000). Med Sci Sports Exerc 32: S498-504
Blair SN, Kohl HW, Gordon NF and Paffenbarger RS Jr (1992).
Annu Rev Public Health 13: 99-126
Bradley CB, McMurray RG, Harrell JS and Deng S (2000). Med Sci
Sports Exerc 32: 2071-8
Brooks-Gunn J, Warren MP, Rosso J and Gargiulo J (1987). Child Dev
58: 829-41
Faith MS, Berman N, Heo M, Pietrobelli A, Gallagher D, Epstein LH,
Eiden MT and Allison DB (2001). Pediatrics 107: 1043-8
Hernandez B, Gortmaker SL, Colditz GA, Peterson KE, Laird NM and
Parra-Cabrera S ( 1999). Int J Obes Relat Metab Disord 23: 845-54
Kimm SY, Glynn NW, Kriska AM, Barton BA, Kronsberg SS, Daniels
SR, Crawford PB, Sabry ZI and Liu K (2002). N Engl J Med
347:709-15
Klesges RC, Shelton ML and Klesges LM (1993). Pediatrics 91: 281-6
Lindquist CH, Reynolds KD and Goran MI (1999). Prev Med 29:
305-12
Marshall SJ, Biddle SJH, Sallis JF, McKenzie TL and Conway TL
(2002). Pediatr Exerc Sci 14: 401-417
McLaughlin JE, King GA, Howley ET, Bassett DR Jr and Ainsworth
BE (2001). Int J Sports Med 22: 280-4
The National Institute of Child Health and Human Development Study
of Early Child Care and Youth Development Network (2003).
Archives of Pediatric and Adolescent Medicine 157: 185-190
Petersen AC, Crockett L, Richards M and Boxer A (1988). Journal of
Youth and Adolescence 17: 117-133
Robinson TN (1999). JAMA 282: 1561-7
World Health Organization: 55th World Health Assembly. (Mar 27,
2002) Diet, physical activity, and health [On-line]. Retrieved May 15,
2003, from http://www.who.int
revista
19.9.03
0:50
Página 171
RISK INDICATORS FOR RECURRENT NON-SPECIFIC
LOW-BACK PAIN IN CHILDREN
Jones Michelle1, Stratton Gareth2, Reilly Tom2, Unnithan Vish3
1
2
3
Department of Sport and Physical Education, Edge Hill College, UK
Liverpool John Moores University, UK
Syracuse University, USA
Keywords: low-back pain, recurrence, risk indicators
Recurrent non-specific low-back pain represents a significant
health problem in children and as such, it is important to
appreciate risk indicators related to its onset. The aims of this
investigation were to a) evaluate biological risk indicators for
recurrent non-specific low-back pain in children and b) present
a conceptual model for the development of non-specific recurrent low-back pain in children. To fulfil the first aim a matched
case-control design was utilised involving 28 children with
recurrent low-back pain (RLBP, boys n=15, girls n=13,
age=14.9(0.7) years) and 28 matched controls (CONT, boys
n=15, girls n=13, age=14.9(0.7) years) with no history of
low-back pain. Measures of stature, mass, sitting height, sexual
maturity (Tanner self-assessment), lateral flexion of the spine,
lumbar sagittal plane mobility (modified Schober), hip range of
motion (Leighton flexometer), back and hamstring flexibility
(sit-and-reach), and trunk muscle endurance (number of situps) were performed using standardised procedures with
established reliability. Backward stepwise logistic regression
analysis was performed with the presence/absence of recurrent
low-back pain as the dichotomous dependent variable and the
biological measures as the independent variables. Significance
was set at p<0.05. Hip range of motion (p=0.045), trunk muscle endurance (p=0.001), lumbar sagittal plane mobility
(p=0.032) and lateral flexion of the spine (p=0.008) were
identified as significant risk indicators of recurrent low-back
pain. Follow-up analysis indicated symptomatic subjects had
significantly reduced lateral flexion of the spine
(RLBP=197(25) mm, CONT=221(22) mm, p=0.000), lumbar
sagittal plane mobility (RLBP=70(9) mm, CONT=77(9) mm,
p=0.002) and trunk muscle endurance (RLBP=37(6) sit-ups,
CONT=42(8) sit-ups, p=0.003). These risk indicators identify
the potential for exercise as a primary or secondary prevention
method. To fulfil the second aim the findings of the current
study were taken into account along with the findings of a systematic review of 21 previous research investigations. Overall
it was identified that the risk of low-back pain is multifactoral
and future research should evaluate complete models including
biological, psychosocial and individual risk indicators. A conceptual model of the development of recurrent non-specific
low-back pain in children will be presented.
171
revista
19.9.03
0:50
Página 172
revista
19.9.03
0:50
Página 173
Author index
A
AberbergaAugskalne, Liga — 103
Afonso, Bela — 143
Alves, Francisco — 107
Amendoeira, Patrícia — 36
Amorim, Leila — 137
Andersen, Lars Bo — 14, 55, 162
Andreacci, Joseph — 45
Araújo, Carlos — 160
Armstrong, Neil — 78, 84, 94, 111, 112, 131
Arruda, Manuel — 35
Aznar, Susana — 161
B
Baggett, Chris — 101
Ball, Claire — 84
Bangdiwala, Shrikant — 101
Baquet, Georges — 102, 162
Barnes, Joel D — 134, 142
Bar-Or, Oded — 20
Barron, Mary — 12
Batista, RCJ — 111
Bedu, Mario — 74, 121
Bentué-Ferrer, Dominique — 92
Bernardo, Carla — 108
Berthoin, Serge — 102, 162
Berthon, Phanélie — 92
Beunen, Gaston — 11, 31, 36, 73, 134
Biddle, Stuart — 15
Biros, Patricia — 53
Blimkie, Cameron JR — 22
Boisseau, Nathalie — 92, 105
Boogaerts, Inge — 68
Botelho Gomes, Paula — 143, 157, 160
Bouchard, Claude — 26
Bracko, Michael — 111
Bragada, José — 107
Brandão, Eurico — 34, 145
Brown, Richard — 31
Burgess, Darren — 31
Burke, Stephen — 31
C
Cabo, Zita — 31
Cabrera, Marco E — 79
Cairney, John — 127
Calzolari, Armando — 61
Calzolari, Flaminia — 61
Campos, Ana — 108
Capel-Davies, Anna — 47
Caputo, Jennifer — 62
Carlson, John — 31, 82
Carlson, John S — 93
Carvalho, Alberto — 31
Carvalho, Carlos — 31
Carvalho, Nuno — 65
Cheng, Chi Hong — 93
Chia, Michael YH — 112, 115
Christen, Gregor — 52
Claessens, Albrecht — 36, 68, 73, 134
Coelho e Silva, Manuel — 36
Cohen, Jacqueline — 51
Colaço, Paulo — 163
Collomp, Katia — 100
Conceição, Filipe — 163
Copeland, Jennifer L — 134, 142
Côrte-Real, Alda — 157
Courteix, Daniel — 91, 93, 100
Craig, Ian — 62
Crawford, Kim — 45
173
revista
19.9.03
0:50
Página 174
Author index
Creighton, Dana — 137
Crespo, Maria — 36, 134
Crosio, Gaia — 61
Cumming, Sean P — 12
Cunha e Silva, Paulo — 157
Cura, João — 145
Cura, Pedro — 145
D
De Bourdeaudhuij, Ilse — 17, 132
De Ste Croix, Mark — 78, 111
Deighan, Martine — 78, 111
Delamarche, Paul — 92
Deruelle, Fabien — 102
Doré, Eric — 74, 121
Duarte, José AR — 150
Dube, John — 45
Duché, Pascale — 74
Ducher, Gaële — 91
E
Edmunds, Sarah — 45
Esliger, Dale W — 134, 142
Eston, Roger — 65, 151
Eyskens, Benedicte — 62
F
Fabre, Claudine — 102
Fairclough, Stuart J — 129
Faludi, Judit — 122
Farkas, Anna — 36, 122
Farpour-Lambert, Nathalie J — 63
Faught, Brent E — 127
Fellingham, Gilbert — 111
Fernandes, Ricardo — 108
Fernhall, Bo — 89
Ferrão, Nuno — 36
Ferreira, I — 85
Ferreira, Isabel — 56
Ferreira, João CV — 147, 155
Ferreira, José V — 160
Figueiredo, António — 36
Flouris, Andreas D — 127
Fontes, Ribeiro CA — 111
Foricher, Jean-Marc — 92
Fragoso, Isabel — 107
Freitas, Duarte Luís — 36, 134
174
Froberg, Karsten — 55
Frost, Stephen — 31
Furriel, Ricardo — 157
G
Garganta, Rui — 35, 156
Garrido, Nuno — 66
Geithner, Christina A — 66
Gewillig, Marc — 62, 67
Giordano, Ugo — 61
Giugliano, Rodolfo — 152
Glenn, Sheila — 45
Gonçalves, Pedro — 65
Goss, Fredric — 45
Goulart, Luis F — 35
Graça, Amândio — 156, 157, 160
Gratas-Delamarche, Arlette — 92
Green, David — 31
Greve, Gottfried — 57, 59
Griffith, Gareth — 62
Griffith, Kelly — 62
Grossner, Colleen M — 79
Guerra, Myriam — 89
Guerra, Sandra — 150
Guerra, Tasso C — 152
Guinhouya, Comlavi — 102, 162
H
Hackett, Allan F — 141
Halvorsen, Thomas — 53
Hans, Didier — 63
Hansen, Henrik Steen — 55
Harrell, Joanne — 101, 135, 137, 168
Hasbani, Keren — 53
Hay, John A — 127
Hebestreit, Alexandra — 52
Hebestreit, Helge — 52
Heimdal, John Helge — 53
Helgheim, Vegard — 57, 59
Hespanhol, Jefferson E — 35
Hirth, Asle — 57
Hitchen, Peter — 47
Hofer, Michael — 63
Högler, W — 22
Huber, Martha — 52
Hughson, Richard — 52
revista
19.9.03
0:50
Página 175
Author index
I
Ihász, Ferenc — 40, 122, 124
Ildikó, Vajda — 36, 122, 124, 139
Ingledew, David K — 151
Instebø, Arne I — 57, 59
J
Jackson, Allan — 105
Jaffré, Christelle — 91, 93, 100
Janeira, Manuel — 34, 145
Jauregui, Edtna — 47
Jimenez, Antonio — 47
Johnson, Emily M — 79
Jones, Michelle — 47, 64, 171
Jürimäe, Jaak — 152
Jürimäe, Toivo — 147, 152
K
Keefer, Daniel — 62
Keller-Marchand, Laetitia — 63
Kemper, Han CG — 20, 56, 85
Kontos, Anthony P — 12
Koppes, LLJ — 20
Kowallis, Ruth — 45
Kriemler, Susi — 52, 100
L
Lacerda, Teresa — 157
Lamb, Elizabeth — 141
Lecoq, Anne-Marie — 82
Lee, Anthea — 31
Lees, Adrian — 75
Lefevre, Johan — 36, 68, 132, 134
Leitão, Carlos — 66
Leppik, Aire — 152
Lespessailles, Eric — 93
Leung, Maurice — 93
Loos, Ruth — 73
Lopes, Tiago — 65
Lopes, Vítor P — 31, 145, 147, 154, 155
Lopez, Taylor J — 47
M
MacLaren, Don PM — 75
MacLeod, Kenneth — 84
Maes, Hermine H — 73
Mahon, Anthony D — 92
Maia, José AR — 31, 35, 36, 107, 134, 145, 147, 154,
155, 156, 163
Malina, Robert — 12, 36
Mandigout, Stephane — 82
Marques, António — 31, 36, 134, 154, 163
Marques-Vidal, Pedro — 98
Martin, Ronan — 74, 121
Massart, Alain — 36
Matton, Lynn — 132
McBride, Michael — 51
McManus, Alison — 93
McMurray, Robert G — 135, 137, 168
Mendonça, Denise — 156
Mertens, Luc — 62
Mesquita, Isabel — 161
Mészáros, János — 122, 124, 139
Mészáros, Zsófia — 36, 122, 124, 139
Metz, Kenneth — 45
Middlebrooke, Andrew — 84
Miller, Susan J — 12
Minderico, Claudia — 86, 95, 98
Mohácsi, Ágnes — 40
Mohácsi, János — 40, 124, 139
Montfort, Veronica — 131
Morais, Francisco P — 145
Morano, Peter — 12
Moreno, Duarte — 163
Morgan, Don — 62
Morse, Chris — 78
Mota, Jorge — 25, 150
Moura, Walcymar — 152
Mourão-Carvalhal, Maria — 66
Mucci, Patrick — 102
Mullan, E — 137
Murray, Robert G. — 101
N
N’Guyen Long Dang — 82
Narici, Marco V — 78
Naughton, Geraldine — 31, 82
Negreiros, Núbio — 152
Nguyen, Long-Dang — 83
Nigro, Antonia — 61
Norgård, Gunnar — 59
Noronha, Cecília — 107
Nottin, Stephane — 83
Nourry, Cédric — 102
175
revista
19.9.03
0:50
Página 176
Author index
Novais, Bruno — 34
Nunes, Cristiano G — 35
O
Obert, Philippe — 82, 83
Oliveira, José — 150
Oliveira, Ana — 166
Ornelas, Rui — 88
P
Parfitt, Gaynor — 47
Paridon, Stephen — 51
Paulos, Francisco — 161
Pearce, Patricia F — 135, 137, 168
Peat, Jennifer — 31
Pedaste, Jaan — 147
Pennell, Michael — 101, 135, 168
Pereira, Simonete — 35
Persaud, Chandarika — 105
Petrekanits, Máté — 40
Philippaerts, Renaat — 68, 132
Pinto, Dimas — 157
Pitetti, Kenneth H — 63, 89
Poortmans, Jacques R — 105
Powell, Clare — 65
Powell, Sarah M — 151
Prista, António — 31, 154
Prókai, András — 36, 40, 122, 124, 139
Prouteau, Stéphanie — 91, 93
Q
Queirós, Paula — 157
R
Ratel, Sebastien — 78
Reilly, Tom — 64, 171
Reybrouck, Tony — 62, 67
Ribeiro, José C — 150
Riddoch, Chris — 161
Rizzoli, René — 63
Robertson, Robert J — 45
Roche, Denise — 45
Rodrigues, António — 36, 134
Roksund, Ola D — 53
Rolim, Ramiro — 163
Roriz, Paulo — 31
Rosado, António — 161
176
Rowland, Thomas — 18
Rowlands, Ann V — 151, 154, 155
Rutkowski, Jason — 45
S
Sampaio, Jaime — 34
Santa-Clara, Helena — 88
Santos, Amândio — 36, 111
Santos, Fátima — 156
Santos, Paula — 150
Santos, Paulo — 107
Saranga, Sílvio — 31, 154
Sardinha, Luís B — 86, 88, 95
Sardoeira, Teresa — 160
Scanlin, Thomas — 51
Schaffer, MS — 67
Schall, Joan — 51
Schlegel, Christian — 100
Seabra, André — 35, 145, 156
Searl, John — 31, 82
Segadal, Leidulf — 59
Serratto, Maria — 55
Shore, Angela — 84
Siegel, Shannon R — 66
Silva Neto, Leonardo — 35
Silva, Pedro — 150
Silva, Adília — 166
Silva, Analiza — 86, 95
Silva, António — 66
Silva, Celso — 36, 134
Silva, Domingos — 35
Silva, Paula — 157, 160
Silva, Rui G — 145
Skadberg, Britt — 53
Snee, Brooke — 45
Soares, Susana — 108
Sobral, Francisco — 36
Sööt, Terje — 152
Sousa, Filipa — 65
Stallings, Virginia — 51
Stecken, François — 82
Stehouwer, CDA — 85
Stephens, Brooke R — 92
Stevens, Sarah L — 154
Stoedefalke, Kerstin — 112
Stratton, Gareth — 45, 47, 64, 75, 129, 137, 141,
150, 171
revista
19.9.03
0:50
Página 177
Author index
T
Taks, Marijke — 132
Tatár, András — 36, 40, 122, 124, 139
Tavares, Fernando — 152
Taylor, Amy L — 54, 67
Taylor, Suzan R — 75, 141
Telama, Risto — 25
Terbah, Mohamed — 83
Thom, Jeanette — 78
Thomas, Philip WM — 155
Thomis, Martine — 36, 68, 73, 134
Tolfrey, Keith — 78
Tournaire, Nicolas — 91
Tremblay, Mark S — 134, 142
Trusen, Andreas — 52
Tseh, Wayland — 62
Turchetta, Attilio — 61
Twisk, Jos — 56, 85, 121
W
Wallymahmed, Aktar — 45
Wedderkopp, Niels — 55
Weixel, Cheryl A — 66
Welsman, Joann — 94, 112
Weymans, Maria — 62
Wiggins, JW — 67
Wijndaele, Katrien — 132
Williams, Craig — 78, 131
Winsley, Richard — 94
Wolfe, Robert R — 54, 67
Wondra, Valarie C — 63
Wood, Louise — 78
U
Unnithan, Vish — 64, 171
Uvacsek, Martina — 36, 139
Z
Zemel, Babette — 51
Ziegler, James W — 53
Zsidegh, Miklós — 36, 122, 124, 139
Zsidegh, Petra — 40
V
Vajda, Ildikó — 36, 124, 139
Van Gesselen, Steven — 62
van Koolwijk, Leonieke — 56
Van Langendonck, Leen — 68
van Mechelen, Willem — 56, 85
Vanden Eynde, Bart — 73
Van-Praagh, Emmanuel — 121
Vasconcelos, Olga — 163, 166
Vasques, Catarina — 147
Vassilopoulos, Will — 78
Vaz, Maria LG — 19
Vaz, Vasco — 36
Vieira, Filomena — 107
Vieira, Luísa — 31
Vilar, Sónia — 108
Vilas-Boas, João P — 65, 108
Ville, Nathalie — 92
Vinckx, Jos — 67
Vinet, Agnes — 82
Vint, Peter — 62
Vlietinck, Robert — 73
Y
Yang, Xiaolin — 25
Yetman, Anji T — 54, 67
Yung, Tony — 31, 93
177
revista
19.9.03
0:50
Página 178
revista
19.9.03
0:50
Página 179
NORMAS DE PUBLICAÇÃO
Tipos de publicação
Regras gerais de publicação
Preparação dos manuscritos
Investigação original
A RPCD publica artigos originais relativos a todas as áreas
das ciências do desporto.
Os artigos submetidos à
RPCD deverão conter dados
originais, teóricos ou experimentais, na área das ciências
do desporto. A parte substancial do artigo não deverá
ter sido publicada em mais
nenhum local. Se parte do
artigo foi já apresentada
publicamente deverá ser
feita referência a esse facto
na secção de
Agradecimentos.
Os artigos submetidos à
RPCD serão, numa primeira
fase, avaliados pelos editores-chefe e terão como critérios iniciais de aceitação:
normas de publicação, relação do tópico tratado com
as ciências do desporto e
mérito científico. Depois
desta análise, o artigo, se
for considerado previamente
aceite, será avaliado por 2
“referees” independentes e
sob a forma de análise
“duplamente cega”. A aceitação de um e a rejeição de
outro obrigará a uma 3ª
consulta.
Aspectos gerais
Cada artigo deverá ser
acompanhado por uma
carta de rosto que deverá
conter:
– Título do artigo e nomes
dos autores;
– Declaração de que o artigo
nunca foi previamente
publicado;
Revisões da investigação
A RPCD publica artigos de
síntese da literatura que
contribuam para a generalização do conhecimento em
ciências do desporto.
Artigos de meta-análise e
revisões críticas de literatura
são dois possíveis modelos
de publicação.
Comentários
Comentários sobre artigos
originais e sobre revisões da
investigação são, não só
publicáveis, como são francamente encorajados pelo
corpo editorial.
Estudos de caso
A RPCD publica estudos de
caso que sejam considerados
relevantes para as ciências
do desporto. O controlo
rigoroso da metodologia é
aqui um parâmetro determinante.
Revisões de publicações
A RPCD tem uma secção
onde são apresentadas revisões de obras ou artigos
publicados e que sejam considerados relevantes para as
ciências do desporto.
Formato
– Os manuscritos deverão
ser escritos em papel A4
com 3 cm de margem, letra
12 e com duplo espaço;
– As páginas deverão ser
numeradas sequencialmente, sendo a página de título
a nº1;
– É obrigatória a entrega de
4 cópias;
– Uma das cópias deverá ser
original onde deverá incluir
as ilustrações também originais;
Dimensões e estilo
– Os artigos deverão ser o
mais sucintos possível; A
especulação deverá ser apenas utilizada quando os
dados o permitem e a literatura não confirma;
– Os artigos serão rejeitados
quando escritos em português ou inglês de fraca
qualidade linguística;
– As abreviaturas deverão
ser as referidas internacionalmente;
Página de título
A página de título deverá
conter a seguinte informação:
– Especificação do tipo de
trabalho (cf. Tipos de
publicação);
– Título conciso mas suficientemente informativo;
– Nomes dos autores, com a
primeira e a inicial média
(não incluir graus académicos)
– “Running head” concisa
não excedendo os 45 caracteres;
– Nome e local da instituição onde o trabalho foi
realizado;
– Nome e morada do autor
para onde toda a correspondência deverá ser
enviada;
Página de resumo
– Resumo deverá ser informativo e não deverá referir-se ao texto do artigo;
– Se o artigo for em português o resumo deverá ser
feito em português e em
inglês;
– Deve incluir os resultados
mais importantes que
suportem as conclusões do
trabalho;
Deverão ser incluídas 3 a 6
palavras-chave;
– Não deverão ser utilizadas
abreviaturas;
– O resumo não deverá exceder as 200 palavras;
Introdução
– Deverá ser suficientemente
compreensível, explicitando claramente o objectivo
do trabalho e relevando a
importância do estudo face
ao estado actual do conhecimento;
– A revisão da literatura não
deverá ser exaustiva;
Material e métodos
– Nesta secção deverá ser
incluída toda a informação
que permite aos leitores
realizarem um trabalho com
a mesma metodologia sem
contactarem os autores;
– Os métodos deverão ser
ajustados ao objectivo do
estudo; deverão ser replicáveis e com elevado grau de
fidelidade;
– Quando utilizados humanos deverá ser indicado
que os procedimentos utilizados respeitam as nor-
revista
19.9.03
0:50
Página 180
mas internacionais de
experimentação com
humanos (Declaração de
Helsínquia de 1975);
– Quando utilizados animais
deverão ser utilizados
todos os princípios éticos
de experimentação animal
e, se possível, deverão ser
submetidos a uma comissão de ética;
– Todas as drogas e químicos
utilizados deverão ser
designados pelos nomes
genéricos, princípios activos, dosagem e dosagem;
– A confidencialidade dos
sujeitos deverá ser estritamente mantida;
– Os métodos estatísticos
utilizados deverão ser cuidadosamente referidos;
Resultados
– Os resultados deverão apenas conter os dados que
sejam relevantes para a
discussão;
– Os resultados só deverão
aparecer uma vez no
texto: ou em quadro ou
em figura;
– O texto só deverá servir
para relevar os dados mais
relevantes e nunca duplicar
informação;
– A relevância dos resultados
deverá ser suficientemente
expressa;
– Unidades, quantidades e
fórmulas deverão ser utilizados pelo Sistema
Internacional (SI units).
– Todas as medidas deverão
ser referidas em unidades
métricas;
Discussão
– Os dados novos e os
aspectos mais importantes
do estudo deverão ser relevados de forma clara e
concisa;
– Não deverão ser repetidos
os resultados já apresentados;
– A relevância dos dados
deverá ser referida e a comparação com outros estudos deverá ser estimulada;
– As especulações não
suportadas pelos métodos
estatísticos não deverão ser
evitadas;
– Sempre que possível, deverão ser incluídas recomendações;
– A discussão deverá ser
completada com um parágrafo final onde são realçadas as principais conclusões do estudo;
Agradecimentos
Se o artigo tiver sido parcialmente apresentado
publicamente deverá aqui
ser referido o facto;
Qualquer apoio financeiro
deverá ser referido;
Referências
– As referências deverão ser
citadas no texto por número e compiladas alfabeticamente e ordenadas numericamente;
– Os nomes das revistas
deverão ser abreviados
conforme normas internacionais (ex: Index
Medicus);
– Todos os autores deverão
ser nomeados (não utilizar
et al.)
– Apenas artigos ou obras
em situação de “in press”
poderão ser citados. Dados
não publicados deverão ser
utilizados só em casos
excepcionais sendo assinalados como “dados não
publicados”;
– Utilização de um número
elevado de resumos ou de
artigos não “peer-reviewed” será uma condição de
não aceitação;
Exemplos de referências
ARTIGO DE REVISTA
1 Pincivero DM, Lephart
SM, Karunakara RA
(1998). Reliability and precision of isokinetic
strength and muscular
endurance for the quadriceps and hamstrings. Int J
Sports Med 18: 113-117
LIVRO COMPLETO
Hudlicka O, Tyler KR
(1996). Angiogenesis. The
growth of the vascular system. London: Academic
Press Inc. Ltd.
CAPÍTULO DE UM LIVRO
Balon TW (1999).
Integrative biology of nitric
oxide and exercise. In:
Holloszy JO (ed.). Exercise
and Sport Science Reviews
vol. 27. Philadelphia:
Lippincott Williams &
Wilkins, 219-254
FIGURAS
Figuras e ilustrações deverão ser utilizadas quando
auxiliam na melhor compreensão do texto;
As figuras deverão ser
numeradas em numeração
árabe na sequência em que
aparecem no texto;
Cada figura deverá ser
impressa numa folha separada com uma legenda
curta e concisa;
Cada folha deverá ter na
parte posterior a identificação do autor, título do artigo. Estas informações
deverão ser escritas a lápis
e de forma suave;
As figuras e ilustrações
deverão ser submetidas
com excelente qualidade
gráfico, a preto e branco e
com a qualidade necessária
para serem reproduzidas
ou reduzidas nas suas
dimensões;
As fotos de equipamento
ou sujeitos deverão ser evitadas;
QUADROS
Os quadros deverão ser
utilizados para apresentar
os principais resultados da
investigação.
Deverão ser acompanhados
de um título curto;
Os quadros deverão ser
apresentados com as mesmas regras das referidas
para as legendas e figuras;
Uma nota de rodapé do
quadro deverá ser utilizada
para explicar as abreviaturas utilizadas no quadro.
Endereço para envio de artigos
Revista Portuguesa de
Ciências do Desporto
Faculdade de Ciências do
Desporto e de Educação
Física da Universidade
do Porto
Rua Dr. Plácido Costa, 91
4200.450 Porto
Portugal
revista
19.9.03
0:49
Página 1
Publicação semestral — Vol. 3, Nº 2 — Setembro 2003, Suplemento — ISSN 1645–0523 — Dep. Legal 161033/01
Setembro
Vol. 3, 2003,
Nº 2 Suplemento
Programa Operacional
Ciência, Tecnologia, Inovação
do Quadro Comunitário
de Apoio III
apoio da Fundação
Calouste Gulbenkian
revista portuguesa de
ciências do desporto
Volume 3 · Nº 2
Setembro 2003
Suplemento

revista portuguesa de ciências do desporto

Transcription

Similar documents

Workshop 1C

Georgy-Porgy

The Rampage - Worth County Schools

FIFTH DIMENSION - University of California, San Diego

7:07 Attending: Matt Biscan, Matt Fisher, Melissa Nilles, Suzanne

Our Group Homes - Heart For Orphans

HW Jan 9-16 - WRDSB teachers

Print out for your friends and schools!

17magazine`s