Being
able to understand how the Human Movement System works and how it can affect an
individual’s performance is critical. Taking a look into the set up of the
system, it has been shown that the joint support system, which is responsible
for supporting the joints of the body, can be split into two different units, the
local muscular system ( Stabilizers)
and global
muscular systems ( Movement).
The local muscular
system is comprised of stabilizers, or muscles that help keep a joint in place
or limit movement.
The global muscular system encompasses most of
the major movement muscles and the muscles are more superficial.
With
these two systems in mind one must have ideal functional posture, through and
with the help of the systems mentioned, in order to have the least amount of
stress on the kinetic chain. Dysfunction can come about through less than ideal
posture, which has a systemic way of being identified.
To
have ideal posture the individual would like to have a strong kinetic chain,
the 3 links in that chain are
1. Myofascial
(muscular/ tissue/ length tension relationships/ reciprocal inhibition)
2. Neural
( electrical impulses/ force couple relationships)
3. Articular
( joint/ arthrokinematics)
A
snag in a part of the chain can ultimately cause the start of the cumulative
injury cycle. The worst case scenario if injury, poor posture, and/ or muscular
imbalance are introduced into the human movement system is, reoccurring injury.
1. Myofascial
Let’s
say that we have a volleyball player that has just suffered their first ankle
sprain. It has been suggested that a lateral ankle sprain can be caused by
limited range of motion in the sagittal plane (dorsiflexion)(2). Another study
also found that strength in the plantar flexors also played a role in ankle
sprains in volleyball players and in army recruits.(1, 3) It can be inferred that
lack of strength in the dorsiflexors or
over active plantar flexors can be the issue. In this case a over active
plantar flexor (i.e. gastrocnemius and/or
soleus) would be a dysfunction in the myofascial potion of the kinetic
chain(1). This can also be referred to as a length tension relationship
dysfunction. A muscle has a set length where it will be at its optimal
functionality, and when that length is shortened, as it is in this case by an
over active muscle, it can cause dysfunction. This can also lead to reciprocal
inhibition, which is where the antagonist of the over active agonist will
decrees the neural drive of the antagonist. This is a snag in the first of the
3 links.
2. Neural
Continuing with what could happen with this dysfunction,
once the antagonist has decreased neural drive another phenomenon begins to
surface, synergistic dominance. Synergistic dominance is the improper
recruitment of synergistic muscles, or muscle that have the same function of
that muscle, (neural chain) in this case it would be the dorsiflexors of the
ankle.
3. Articular
The reason this is not ideal, is that the
synergistic muscular that is know taking main stage is being over worked and
can become over used and weak. This weakness of the dorsiflexors has been shown
to limit range of motion in the ankle ( articular chain), which in some studies
has been shown to cause ankle sprains (2).
The next post will review what one as an athlete,
fitness client, or the sports trainer can do to help limit this from happening.
Oh yeah I'm a Mavericks fan, hence the first image!!
References:
1. Hadzic, V., Sattler, T., Topole, E., Jarnovic, Z.,
Burger, H., & Dervisevic, E. (2009). Risk factors for ankle sprain in
volleyball players: A preliminary analysis. Isokinetics & Exercise
Science, 17(3), 155-160.
2. M. de Noronha, K.M. Refshauge, R.D. Herbert,
S.L. Kilbreath
and J. Hertel, Do voluntary
strength, proprioception, range of
motion, or postural sway predict
occurrence of lateral ankle
sprain? British Journal of
Sports Medicine 40 (2006), 824–828.
3. R. Pope, R. Herbert and J.
Kirwan, Effects of ankle dorsiflexion
range and pre-exercise calf
muscle stretching on injury
risk in Army recruits, Australian
Journal of Physiotherapy 44
(1998), 165–172.