proprioceptive neuromuscular facilitation

PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION
(PNF): A TECHNIQUE OR A SYSTEM?
I’d
Ramez Antoun, PT, DPT
like to start off by saying I
am by no means an expert
in PNF or consider myself
a PNF clinician just yet, but I am currently
a resident at the PNF residency program in
Vallejo, California, where the roots of Maggie
Knott and Dr. Kabat ‘s work started in the
United States. This write up is simply me
sharing what I’ve learned so far from all the
incredible PNF instructors here in Vallejo.
are integrating into the trunk. Consequently,
PNF is not just a technique, it is a SYSTEM
that can be used for both a screen (at a basic
level), and/or an assessment/evaluation which
would then lead to specific and purposeful
treatment plan/techniques.
Many people think of PNF as a technique for
stretching or exercises for the arms and legs
in Diagonal 1 (D1)/ Diagonal 2 (D2) patterns.
However, PNF is not just stretching using
hold relax/contract relax; or just arm and
leg patterns like D1 (flex/add/ER)/D2 (Flex/
abd/ER), and chops/lifts. Think of PNF as
a way of means of feeding the sensorimotor
system specific and purposeful proprioceptive
information to create a purposeful and
functional motor strategy The components
of PNF patterns of facilitation were actually
the last thing developed by Maggie Knott and
Dr. Herman Kabat as a means of tapping into
the DEEP stabilizers of the trunk through the
limb-trunk interlinking segments of the body,
the scapula/pelvis. Just like any exercise/
human movement, the PNF arm/leg patterns
have to demonstrate/activate dynamic trunk
stabilization from start to finish, and if they
don’t, then further assessment is required.
For example if the limb-trunk interconnecting
segments, pelvis or scapula, are not integrated
into the trunk than it’s very difficult to expect
the limb to be integrated into the trunk.
Hence a limb pattern can lead you to further
investigate/asses how or if the scapula/pelvis
1. MOTOR CONTROL: How the brain
controls movement
• REFLEX MODEL
• HIERARCHICAL/
DEVELOPMENTAL MODEL:
How the CNS develops/integrates
higher level postures/movements as
the CNS matures from a bottoms up
direction (from a spinal cord to the
cortical level)
• SYSTEMS MODEL
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PNF is based on PRINCIPLES that follow
movement based areas of study. Areas of study
to provide support for PNF are:
Something that is CRUCIAL to remember
is that these three areas of study are not and
cannot be exclusive from one another; they are
interdependent and feed into each other. How
they feed into each other will make more sense
as you read on.
I’ll briefly go into each area of study and
elaborate just a bit.
1. MOTOR CONTROL
Within this area of study there are 3 models
that still seem to hold valid from a scientific
standpoint:
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• THE REFLEX MODEL:
This model is based on Charles Sherrington’s
work, a neurophysiologist in the late 1800s and
early 1900s, who decerebrated cats (basically
removing the cerebral cortex by cutting through
the brainstem of animals) and applied a form of
afferent stimulus through stretch or some sort
of noxious input to the body to see the efferent
(motor) output. He found that no matter the
stimulus, there would always be a response, a
stereotypical muscle response (remember this
is after the cerebral cortex was removed). “For
Sherrington, reflexes were the building blocks
of complex motor behavior. He believed that
complex behavior could be explained through
the combined action of individual reflexes
that were chained together (Sherrington,
1947) (Shumway-Cook, Woolacott 2012).
We know that movement can’t be exclusively
explained via reflexes, given our
conscious mind, but reflexes no
doubt have a huge influence on
movement behavior. Many of Dr.
Kabat’s basic principles for PNF
(for example manual contacts/
appropriate application of a quick
stretch) came from Sherrington’s
work and his reflex model.
•HIERARCHICAL/
DEVELOPMENTAL
MODEL:
This model starts to get into motor development
and comes from the work of Hughlings
Jackson, an English physician, who argued
that the CNS has higher, middle, lower levels
of organizational control. So each successively
higher level in the CNS (spinal cord, brainstem,
midbrain, cortex) demonstrates control (ability
to inhibit) over the level below it. Rudolf
Magnus confirmed this by finding that lower
level reflexes (that live in the brainstem/spinal
cord) were expressed only when cortical centers
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were damaged; similar to what is clinically
found with patients who have hemiplegia
or patients who suffered a traumatic brain
injury. As an interesting side note, some of
these reflexes can even be expressed in the
neurologically intact individual during extreme
circumstances/stress as needed for function;
think of a Javelin thrower and the ATNR reflex.
This model was later used to describe the way
humans progressively develop higher levels of
motor function. Higher level postures start to
become possible as certain reflexes appear and
disappear, or in other words, as higher levels
of the CNS (midbrain/cortex) start to integrate/
modulate the lower level reflexes (brainstem/
spinal cord).
The diagram below over simplifies the concept
of motor development.
Basically, as humans, if we only had a
functioning brainstem/spinal cord level of CNS
control, we would be apedal animals (unable
to be mobile beings, whether through crawling
or walking) and demonstrate primitive reflexes
that we wouldn’t be able to control/inhibit. As
the CNS matures we start to integrate/inhibit
the SC/brainstem level reflexes with the higher
level centers like the midbrain and cortex. It is
this higher center integration that allows us to
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inhibit lower center reflexes making it possible
to attain postures like prone (on our belly) and
quadruped (on our hands and knees). According
to the neuro-pediatricians of DNS (Dynamic
Neuromuscular Stabilization out of Prague
in the Czech Republic), attaining the prone
position is when the CNS learns and starts to
develop purposeful reciprocal motor patterns
(think crawling in prone and quadruped)
which are prerequisite to bipedal locomotion,
aka walking. Reciprocal locomotion starts in
rolling and the prone position, where we learn
how to crawl.
Think of reciprocal locomotion like this: the
L arm and R leg are doing the same action
(i.e propelling us forward while supporting
our body like the baby crawling in the bottom
right picture) while the R arm and L leg are
doing the equal and opposite action, taking a
step forward; That is reciprocal patterns for
locomotion in a lower level postural position.
Walking is nothing more than reciprocal
locomotion without the upper extremity weight
bearing.
When you walk, if you take a step/swing
your L leg forward, your R arm also swings
forward; at the same
time your R leg and
L arm extend behind
you (as in the picture
below).
For example, a patient
with
hemiplegia
who lacks stability
in L stance phase of
gait (which could
be due to many
different
reasons)
may be treated in supine/sidelying with an
extension/abduction lower extremity pattern
(emphasizing end range hold), progressed
to rolling from sidelying to supine (using
same pattern), to prone on elbows/reaching/
crawling, to quadruped, to resisted crawling,
to tall kneeling, to half kneeling depending on
the motoric ability of the patient. Dr. Kabat
took this hierarchical/developmental model
and worked it into prone/supine progressions,
starting with lower level postures and
integrating higher level postures based on
higher levels of neuroanatomical integration
within the CNS. One could argue (based on
the newest research in motor learning) that by
respecting this model we’re not necessarily
creating new motor programs/neuro-motor
behaviors, we’re “simply” re-myelinating
motor programs that already exist within the
CNS, but just haven’t been used since we used
them to learn how to walk the first time.
• SYSTEMS MODEL:
Back in the early 1900s Nicolai Bernstein, a
Russian scientist, looked at the nervous system
in a whole new way. He said: “You can’t
understand the neural control of movement
without understanding the characteristics of
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the system you are moving and the internal and
external forces acting on the body (Bernstein,
1967)” (Shumwaycook-Woollacott 2012).
He considered the body as a mechanical system
that was subject to two forces:
1. EXTERNAL FORCES:
• Think gravity and the environment
2. INTERNAL FORCES
a. Musculoskeletal system
b. Neurological system
Think of the musculoskeletal system as the
elastic & plastic properties of the connective/
soft tissue. Think of the neurological system as
the already learned/automatic motor strategies
from past experiences that are engraved in that
individual’s CNS. Please understand that this
is an oversimplification of the systems model,
because truly there are way more than just two
internal forces acting on our mechanical system
such as the cardiorespiratory & vestibular
system, emotions, intellect, etc.
So, Bernstein realized that this mechanical
system (our bodies) leaves us with a significant
problem when it comes to controlling
movement, called the “Degrees of Freedom”
problem. Think of “degrees of freedom” as the
number of joints and all of their available range
that your body has to control. Think about how
many joints we are born with; all of which can
freely move in various planes of motion (flexion,
extension, rotation). As infants we’re born
with all the mobility (“Degrees of freedom”)
we could possibly need without much stability
which exponentially complicates controlling
authentic movement. What’s interesting is
that we are the only animals that are NOT
born with the ability of reciprocal locomotion/
the ability to walk, hence we’re stuck on our
backs at first. It takes humans about a year to
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LEARN how to walk; unless of course the CNS
does not develop normally or lacks one of its
sensory systems, for example if a baby is born
without vision, what motivation does baby
have to explore his/her environment and figure
out their mobility/stability options to progress
through the developmental milestones? What’s
even more interesting is that no matter where
you are in the world we, as humans, all learn
how to walk before the ability to completely
understand verbal cues/instruction. There are
very characteristic and predictable milestones
in which we achieve certain motoric ability
(for example, when the CNS is developing
“normally” the AVERAGE age babies achieve
quadruped is 8-9 months of age). So if we’re
born with a ton of MOBILITY (all the available
range of motion in all our joints), we then have
to learn/earn our STABILITY, in order to then
learn how to move with control, let’s call that
MOBILITY ON TOP OF STABILITY or
CONTROLLED MOBILITY (truly gained
by learning how to, with control, move a
proximal segment over fixed distal segment).
Let’s logically think this through for a second;
wouldn’t it make sense to learn how to control
all these joints in a synchronized manner first,
by starting at a lower level posture (like laying
on your back) where the “degrees of freedom”
are minimized (aka way less joints to have to
control), where you have a very wide base of
support with a very low center of mass/center
of gravity? Then we can move on to a posture
which introduces more “degrees of freedom”
(a posture that introduces more joints to be
controlled), with a smaller base of support,
and a higher center of mass/center of gravity
like quadruped, then tall kneeling, then half
kneeling then standing. Notice how we would
probably have to go through the sequence of
mobility, stability, then controlled mobility.
Just know that when you’re rehabbing/
working with adults they don’t always have
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to go through each and every stage of the
developmental sequence (debatable), we just
need to find their “weakest link” and find
what developmental stage that they don’t
demonstrate competency in from a mobility,
stability, controlled mobility standpoint.
Do you also see how this progression ties in
beautifully with the hierarchal/developmental
model? If not keep reading.
Bernstein hypothesized that the solution to
this “Degrees of Freedom” problem was
a hierarchal control system (tying into the
previous section) that takes place in the CNS
in which higher centers (Sensorimotor Cortex)
activate lower centers (subcortical areas) and
these subcortical areas activate Synergies, or
chains of muscles that are developmentally/
neurologically and anatomically designed to
work together as a functional unit. Tie this
back to the two internal forces that act on our
mechanical system: Neurological system:
automatic motor behavioral programs that
“wire” these synergistic muscles together
and the Musculoskeletal system. If you read
into Thomas W. Myers’s work and check out
his book Anatomy Trains about myofascial
connections through the body, you’ll see how
he beautifully demonstrates that these muscle
synergies are anatomically woven together
via our fascial matrix and are pretty much
inseparable from a soft tissue stand point.
This concept of synergies provides support
to the PNF trunk and extremity patterns that
were developed by Dr. Kabat based on both
anatomical/neuro-programming relationships
of synergistic muscle groups working together
in harmony with the deep trunk stabilizers.
Bernstein also believed that these stereotypical
muscle chains/synergies working together as a
functional unit, provide us with 3 categories
of movement that are crucial for human
function and they are: Locomotor, Postural,
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and Respiratory synergies.
“Newer views of synergies are saying that a
muscle can belong to multiple synergies; in
addition, an individual muscle has a unique
contribution to each synergy. Finally, the total
activation of a muscle is dependent on both the
simultaneous activation of multiple synergies
containing that muscle and the relative
contribution of that muscle within each of these
synergies” (Shumway-Cook and Woollacott
2012). Dr, Charles Edward Beevor an English
neurologist and anatomist simply compliments
the past quote with his axiom “The brain does
not know muscles, only movements.” So in
terms of movement and motor control, why
do we insist on testing and exercising muscles
in isolation? It seems to make more sense to
test and exercise muscles utilizing movement
patterns that require the synchronization of
synergistic chains of muscles that are already
neurologically hardwired (in our DNA) and
anatomically connected to function as a team
while the body is in various position (Could
Manual Pattern Testing be a supplement to
Manual Muscle Testing in the future?). Let’s
use an example of training glut medius from
two different perspectives: glut medius training
using isolation with clam shells vs. glut med
training using movement patterns/synergies
that involve glut medius as part of the team to
achieve movement in various positions. Let’s
first agree that in various loaded positions like
asymmetrical stance (In-line lunge, hurdle
step, single leg stance) and symmetrical
stance (squat/sit to stand, deadlifting)
Glut med activation is required in various
synergistic patterns and in different muscle
and joint positions. What’s very convenient
is that the same synergistic patterns (which
all incorporate glut med) utilized in loaded
asymmetrical and loaded symmetrical stance
can also be replicated in lower level unloaded
or loaded positions (asymmetrical: active
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straight leg raise, rolling, quadruped with one
leg in extension, half kneeling. Symmetrical:
quadruped, push up, tall kneeling). So although
we can activate glut medius in isolation with
clam shells and show, through EMG studies,
that glut medius is lit up like a christmas tree;
repetitive isolated concentric and eccentric
contractions of the glut med do not allow glut
medius to learn how to coordinate its activation/
timing of activation with its synergistic partners
during loaded asymmetrical and symmetrical
positions. Also as Gray Cook would explain
that doing 3 sets of 10 reps of repetitive
concentric/eccentric contractions is considered
strength training which is applied to muscles
categorized as stabilizers a lot in the movement
profession. But stabilizers’ primary role is
to activate extremely fast (before movement
occurs) to keep a joint in good alignment and
STABILIZE the joint before and while the
bigger mover muscles activate and move the
joint. So stabilizers don’t really need to be all
that isotonically strong as much as they need
to learn how to reflexively activate prior to
and during movement in concert with other
muscles in that synergy in order to provide
authentic dynamic stabilization while the joint
is kept in it’s ideal position (maintaining the
joint’s instantaneous axis of rotation). Gray
Cook’s quote: “Does exercising glut medius
alone exercise the pattern or does exercising
the pattern exercise glut medius?” seems to
correlate with Dr. Kabat’s quote: “The nervous
system is continuous throughout its extentthere are no isolated parts.” Gray Cook and
Dr. Herman Kabat would’ve gotten along
pretty well.
rational/success of PNF application (or ANY
system) is driven from a solid understanding
of the foundation/principles that were derived
from motor control areas of study: THE
REFLEX MODEL, HIERARCHICAL/
DEVELOPMENTAL MODEL, and THE
SYSTEMS MODEL.
For other systems that implement these motor
control concepts to Sports medicine and
Orthopedic populations I urge you to look into
DNS (Dynamic Neuromuscular Stabilization
out of Prague in the Czech Republic), SFMA
(Selective Functional Movement Assessment)
and FMS (Functional Movement Screen).
So although all you can see sometimes is
the tip of the iceberg of PNF (that is D1/D2,
contract relax, chops/lifts); understand that
under the surface of the water is where the
mass of the iceberg lies and the foundation/
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References
1. Alder, Susan . PNF in Practice . Third. Springer Medizin Verlag Heidelberg: 2008. Print.
2. Cook, Gray. Movement. Aptos, CA: On Target Publications, 2010. Print.
3.
Grzybowski, Terry. “Mobility vs. Stability .” PNF. CA, Vallejo. 1997.
4.Liebenson , Craig . Rehabilitation of the Spine. 2nd. Baltimore : Lippincott Williams &
Wilkins, 2007. Print.
5.
Myers, Thomas W. Anatomy Trains. 2nd. Churchill Livingstone, 2001. Print.
6.Shumway-Cook, Anne, and Marjorie H. Woollacott. Motor Control: Integrating Research
into Clinical Practice. 4th. Baltimore, MD: Lippincott Williams & Wilkins , 2012. Print
7.Kobesova , Alena. “Dynamic Neuromuscular Stabilization according to Kolar Level A.”
Athlete’s Performance . Arizona , Phoenix . 2012
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