PE 254

PE 254
Maximal oxygen uptake
ALSO CALLED:
 VO2 max
 Peak aerobic power
 Maximal aerobic power
 Maximum voluntary oxygen consumption
 Cardio-respiratory aerobic capacity
 Maximal cardio-respiratory fitness
 Maximal functional aerobic capacity
VO2 max
 A maximum rate at which an individual can consume O2
during maximal exertion.
 Expressed as the maximum volume of oxygen
consumed/min
 Absolute: litres per min (L/min)
 Relative: milliliters per kilogram per minute
(ml/kg/min)
 1 MET = metabolic equivalent = A unit used to estimate the
metabolic cost oxygen consumption) of physical activity =
3.6 ml O2/kg/min
VO2 max depends on
 3 systems: Pulmonary, Cardiovascular, Muscular
 Cardiac output: stoke volume, heart rate, peripheral resistance
 Muscle blood flow: capillary density
 Hemoglobin content (oxygen-carrying red pigment of the red blood
corpuscles)
 Muscle mass
 Muscle fiber type
 Oxygen extraction: muscle mitochondrial density, oxidative enzymes
 Pulmonary function
Oxygen deficit/oxygen debt
Oxygen Deficit. While exercising intensely the body is sometimes unable to
fulfill all of its energy needs. Specifically, it is unable to intake and absorb
enough oxygen to adequately 'feed' the muscles the amounts of energy needed
to adequately perform the tasks the athlete is requesting from the body. In
order to make up the difference without sacrificing the output, the body must
tap into its anaerobic metabolism. This where the body goes into a mix of
aerobic and anaerobic energy production. While not hugely detrimental,
oxygen deficits can grow to a level that the anaerobic energy system cannot
cover. This can cause performance to deteriorate.
Oxygen Debt. This term describes how the body pays back its debt incurred
above after the exercise is over. You will notice that even after you are done
racing you will continue to breath hard. At this point your body is still trying to
repay the oxygen debt that was created when you were working
hard. Technically, it is excessive post-exercise oxygen consumption.
Oxygen deficit/oxygen debt
Factors affecting VO2 max
 Heredity
 Age
 Sex
 Body size and composition
 Training status
 Types of muscle fibers used during the exercise
 Altitude
 Temperature
Factors affecting VO2 max
Heredity
 It is well established that the limits for developing
fitness capacity are linked to genetic endowment.
 Genetic effect is currently estimated at approximately
20-30% for VO2 max, 50% for maximum heart rate,
and 70% for physical working capacity.
Factors affecting VO2 max
Age
 Children
 Absolute values for girls and boys are similar until age
12
 At age 14 VO2 max value for boys 25% > girls and by
age 16, the difference exceeds 50%.
 Relative values for boys VO2 max remains level at
about 52 ml/kg/min from age 6-16
http://jap.physiology.org/cgi/content/abstract/65/3/1147
Age related changes in VO2 max
Average VO2 max in males
 18-25y 43-46
 36-45y 35-39
 46-55y 32-34
 >65y 25-28
Average VO2 max in females
 18-25y 39-41
 36-45y 31-33
 46-55y 28-30
 >65y 22-24
Age and VO2max in Healthy Subjects
Factors affecting VO2 max
Adults
After age 25 its all down-hill (VO2 max declines at a
rate of 1% per year after age 25)
BUT one’s habitual level of physical activity has far
more influence on aerobic capacity than age!
Factors affecting VO2 max
Sex
 Even among trained endurance athletes, the sex
difference for VO2 max = 15-20% mainly due to
differences in:
• Differences in body composition
• Hemoglobin (oxygen-carrying red pigment of the red
blood corpuscles) concentration
Factors affecting VO2 max
 Body size and composition
An estimated 69% of the differences in VO2 max
scores among individuals can be explained by
variations in body mass
 Mode of exercise
Highest values are generally found during treadmill
exercise, lowest on bicycle ergometer test; specificity is
very important
 Muscle fiber type
Slow oxidative fibers – highest oxygen consumption
Exercise and VO2 max
 Moving from rest to exercise = energy requirements
 Metabolism increases in direct proportion to rate of
work
 As demand for energy increases so does oxygen
consumption (remember the role of oxidation to
produce ATP to do work)
 VO2 eventually peaks = VO2 max
 VO2 may remain constant at max or drop slightly even
through work intensity continues to increase.
 Increased O2 consumption with increasing power
output
Other factors affecting VO2max
 Altitude
Low partial pressure of O2 in the atmosphere
Lower partial pressure of O2 in the arterial blood
Lower hemoglobin saturation
http://jap.physiology.org/cgi/content/abstract/91/3/1113
 Temperature
Higher temperature – higher oxygen consumption
Why VO2 testing?
 A measure of cardiorespiratory endurance gives us an
indication of the individual’s aerobic fitness.
 Endurance athletes generally have a larger capacity for
aerobic energy transfer.
 VO2 max is generally lower (10-20%) for females than
males.
Predicting VO2 max
 Direct measurement of VO2 max requires an extensive
laboratory and specialized equipment as well as
considerable subject motivation.
 Direct tests are not suitable for measuring large groups
of untrained subjects outside of the lab.
 Direct tests are strenuous and thus could pose a
hazard to adults who are not fit
Advantages
 Inexpensive
 No training required
 Short duration
 Safety because of submaximal effort
 VO2 can be estimated
 HR and BP can be monitored
Disadvantages
 Max HR and BP are not measured
 VO2max is not measured directly
 Limited usefulness
Predictive test for aerobic capacity
Although there are many predictive tests available we
only focus on those used most commonly in the lab
 The treadmill test
 YMCA stationary bicycle protocol
 Bench step test
Predictions based on heart rate
 Common tests to predict VO2 max use exercise or
post-exercise HR
 These tests make the use of the essentially linear
relationship between HR and VO2 during various
intensities of light to moderately heavy aerobic
exercise
Assumptions made in VO2 max predictions
 Linearity of HR-VO2 relationship
 Similar maximum HR for all subjects
 Assumed constant economy or mechanical efficiency
during exercise
 Small day to day variations in HR (+/- 5 bpm)
 Method is with 10-20 of real values, good for screening
Relationship between HR and VO2
Calculating VO2max
The formulas:
 Male:
108.844 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR (0.1928)]
 Female:
100.5 – [lbs./2.2 (0.1636)] – [time (1.438)] – [HR (0.1928)]
Calculating VO2max
 Here’s how you do the calculation:
 If you are male, start with the number 108.844. If you are female, begin with 100.5
 Calculate your weight in kilograms by dividing your weight in pounds by 2.2. Then
multiply your weight in kilograms by 0.1636. Finally, subtract the resulting
number from either 108.844 (male) or 100.5 (female). Example: Kathy weighs 139
pounds. (a) 139/2.2= 63.2 kilograms. (b) 63.2 x 0.1636 = 10.34. (c) 100.5-10.34 = 90.16
 Convert the time it took you to jog the mile into a decimal number. Multiply this
decimal number by 1.438. Subtract the result from the last number obtained in
step #2. EXAMPLE: (a) Kathy jogged her mile in 10 minutes and 15 seconds, which is
10.25 minutes. (b) 10.25 x 1.438 = 14.74. (c) 90.16 – 14.74 = 75.42.
 To obtain your VO2max, multiply your heart rate (taken right at the end of the one
mile jog) by 0.1928. Subtract the result from the last number obtained in step #3.
Example: Kathy’s heart rate at the end of the mile was 132. (a) 132 x 0.1928 = 25.45. (b)
75.42 – 25.45 = 49.97. So, Kathy’s VO2max is about 50 milliliters of oxygen per kilogram
of body weight per minute. With a VO2max of 50, she should be able to complete a 5K in
around 29 minutes, a 10K in about 41:20, and a marathon in 3:11.
Prediction equations for bench step
 Men
VO2max = 111.33 – (0.42 x HRREC)
 Women
VO2max = 65.81 – (0.1847 x HRREC)
HRREC = 15 second recovery HR (bpm)
Pre-test screening
 Be sure to carefully follow ALL procedures in lab
manual
 Subject must answer NO to all questions on PAR-Q
(physical activity Readiness Questionnaire) and sign it
in order to carry on with testing
 Subject must complete the submaximal testing
readiness questionnaire
Videos on VO2max tests
 http://www.youtube.com/watch?v=u5xiJ1qpMmA&fea
ture=related
 http://www.youtube.com/watch?v=18-
Fj8ub7Ik&feature=related
 http://www.youtube.com/watch?v=xi9ZGl1Ha3o&feat
ure=related
Monday, September 14th
 Read Chapter 2 before Monday,
September 14th
 Please meet at the Fitness Lab, PE 2A
(across from the Student Wellness
Center) on Monday, September 14th