The following article is part I of a II part
series on the complexity of the non-contact ACL injury. Is the non-contact ACL injury really that complex? With the abundance of research that has been
done and is being done in this area, one would think that we would have figured
it out by now. Yet, we are still looking
for “the answer”. Many feel they have “the
answer” yet injury rates continue to climb, athletes continue to return to
sport with increased risk and their future joint health and performance continues
to be compromised. So one has to ask, why
the complexity? Isn’t it simply
training? The simple answer to that
question is no but it also is not that complex.
Unfortunately training bad movement will simply strengthen bad
movement. No matter the level of the
performance trainer, if they do not understand movement or how to assess
movement, they cannot and will not improve movement but rather only make
compensation strategies stronger. For
example, the US Olympic athlete here demonstrates a significant lateral
shift. In her training, she was squatting
with a significant amount of weight with this lateral shift under the
supervision of a very high level performance coach. In this instance, she simply reinforced and
strengthened her lateral shift, continued to further develop asymmetrical
strength and endurance and set herself up for performance issues and potential
injuries. Is this the fault of the strength
coach? No. If we don’t assess movement as a part of what
we do, how can we quantify it, how would we know how to impact it and how can
we determine if our interventions are changing it? In athletics and especially high performance athletes,
it is sometimes very hard to see unless you know how to assess. If we don’t know how to assess it in the
sciences and biomechanics, how can those in other fields be expected to
know? Or do we know how to assess?
In medical and biomechanical sciences,
sometimes things tend to be overly complicated with the science and the
scientific research and thought process that is done. We look for a scientific reason and answer
for every aspect of movement and correlations with correlation co-efficient of
1.0. In reality, these correlation co-efficients
rarely, if ever exist. So why the
complexity and is there a simple answer?
Yes and no. Simply, movement is
complex and confusing to assess. When we
see movements, like depicted here with this high school dancer, it is hard to
determine what is the root cause or the main factor that is driving the
movement we see. Some would look at this
particular example and conclude this is a foot problem due to the pronation
that is occurring at the foot in this position.
Yet, in a closed kinetic chain, where one link is connected to the next,
there is no way the foot could not move into pronation if the hip is adducted
to this degree. Try it. In a standing position, move your hip in
toward midline a little. Now do it a
lot. What happens to your foot? You feel your arch collapse and your foot
pronates. Yet, the same is true with the
knee. If the foot moves into pronation,
then the knee must also follow along.
Try it. Move your foot into
pronation (collapse your arch) and look what happens to your knee. Your knee moves into adduction. So do you address the foot or do you address
the hip?
To answer that question we must assess
movement. Based on what we know from the
research is there a way to assess athletes in a way that uses the information
we do know and which also leads us, through a process of elimination, to why
they move the way they do? Some have
attempted to do this with an individualized test. In these instances they attempt to use one
test in isolation to determine if the movements are present. That part is simple. The single leg squat above is a clear
indication of risk but does it tell us how to address the movement dysfunction? No. To
get to the root cause, we must have a sequence of tests which lead us, through
a process of elimination, to a root cause or causes (which we will speak about
in a minute). But, in the case above,
there are some key concepts that can look at with an isolated test like this
that starts to lead us to the root cause.
Two of the key concepts we teach clinicians, coaches
and performance trainers is very simple and yet aids in determining the root of
such a complex issue. First, the weak link always falls first under loading and
is a root cause contributing to the movement pattern. Second is the link with the largest magnitude
of deviation under load is a root cause that is resulting in movement observed. Case in point. Take these two athletes performing the exact
same movement, a 31 cm step up. Both of
these athletes are demonstrating adduction past midline which would lead one to
believe the root cause is at the hip.
However, in #1 (soccer player), her ankle is
clearly in a neutral or near neutral position while her hip is in an adducted
position. What was observed on her was
as she started load the extremity with this test that her knee fell into this
adducted position first and as she progressed, her foot began to pronate. Conversely, #2 (cheerleader), when she put
started to load the lower extremity, what was observed was her foot fell into a
pronated position which was then followed by her hip. Using the concepts mentioned above, the weak
link falls first and the link with the largest magnitude of deviation is the
weak link, we can clearly see where the deviations are. In #1 the weak link is the hip and in #2 the
weak link is the ankle. Considering
this, the treatment for the same movement dysfunction would be completely
different and one can speculate if treated the same, the outcome would not be
as good.
Using this concept one can then begin to determine
where the root cause is and how one would address. Simply determining this as a clinician, coach
or strength coach will have an immediate and profound impact on injury rates as
well as performance. Performance,
really? Yes. Look at the mechanics here. Tell me how that cannot impact force
production, kinetic energy transfer or symmetrical strength development. Improvement of these would directly translate
into improved vertical jump, improved sprint speed and improved explosive
power. In other words, improving these
motions has a direct impact on performance.
In part II of this series, we will talk about how
to fully assess movement. More
importantly, how do we simplify so we can impact in a way that reduces injury
and further drives performance.
Build
Athletes to Perform…Build Athletes to Last!™
About
the author: Trent Nessler, PT, DPT, MPT is
CEO of A.C.L., LLC and is a practicing physical therapist with 15 years in
sports medicine and orthopedics. He has masters in physical therapy and
doctorate with focus in biomechanics and motor learning. He is the
founder/developer of the Dynamic
Movement Assessment™, Fatigue Dynamic Movement Assessment™ and author of a textbook “Dynamic Movement Assessment™: Prevent Injury and Enhance
Performance”. Trent is also associate editor of the International Journal of
Athletic Therapy and Training and Member of the USA Cheer Safety Council. For more information, please see our website
at www.aclprogram.com.
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