Activation During Landing Before and After Fatigue in Individuals With or
Without Chronic Ankle Instability

KA, Pietrosimone BG, & Gribble PA.  J Athl Train. 2016; 51 (10): 000.
doi: 10.4085/1062-6050-51.10.01
Take Home Message: Individuals with chronic ankle
instability have higher pre-activation of peroneus longus and gluteus maximus compared
with controls.  A functional fatigue
protocol affected both groups similarly.

Despite chronic ankle instability
(CAI) being common among physically active individuals, it remains unclear why
some patients develop it.  Fatigue can
influence muscle activation patterns, which could contribute to recurrent ankle
sprains.  However, it is unknown if
fatigue affects individuals with CAI differently than those without CAI.   Therefore, these researchers investigated hip
and ankle muscle activity pre and post fatigue among individuals with or
without CAI.  Researchers recruited 16
individuals with CAI and 16 without CAI who were matched based on age, height,
mass, and sex.  Researchers measured
muscle activation of the tibialis anterior, gluteus maximus, gluteus medius,
and peroneus longus before and after a functional fatigue protocol.  The fatigue protocol consisted of sprinting,
shuffling, jumping, and lateral hops until performance detriment or participant
cessation. Overall, CAI participants had higher peroneus longus and gluteus
maximus activation immediately before landing during a lateral hop compared
with the controls.  After the fatigue
protocol both groups had higher tibialis anterior activation than before being
fatigued. The authors found no other differences. 

The findings of this study are
interesting because it shows that physically active individuals with CAI are
“pre-activating” muscles differently than healthy controls to try to protect
the previously injured joint in preparation for landing.  However, it remains unclear if participants
with CAI had these activation patterns prior to developing CAI or if the
activation patterns developed as a result of the injury and subsequent CAI.  It would be interesting to see what the
muscle activity was in the contralateral or healthy limb.  While the activation of the peroneus longus
is an obvious protective mechanism for preventing inversion during landing, the
higher activation of gluteus maximus seems less intuitive.  The authors speculate that a CAI
participant’s gluteus maximus will activate in efforts to prevent femoral
internal rotation, which would stress the ankle joint.  As clinicians, we need to ensure that our
rehabilitation programs are addressing joints further up the kinetic chain – as
there are obvious changes at the hip.    The fatigue protocol was functional and
activity specific, with running, and cutting, and jumping – however, it did not
have much of an effect.  However, tibialis
anterior activity increased in both groups post-fatigue before and after ground
contact.  Clinicians should address this during
the rehabilitation process with endurance training of the tibialis anterior to delay
fatigue.  While the fatigue protocol was
relatively standardized, it would have been interesting to see if heart rate
could have been monitored to give an objective measure of effort or if linear
activity would have resulted in similar effects.  Clinically, we need to remember to address
the entire kinetic chain.  Furthermore,
we may want to consider rehabilitating under fatigued states to replicate
return to sports activities.  

for Discussion:  Have you had any success
performing rehabilitation exercises under fatigued states?  What strategies do you think work best when
trying to work with an athlete with CAI?

Nicole Cattano
by: Jeffrey Driban


Webster, K., Pietrosimone, B., & Gribble, P. (2016). Muscle Activation During Landing Before and After Fatigue in Individuals With or Without Chronic Ankle Instability Journal of Athletic Training DOI: 10.4085/1062-6050-51.10.01