Muscle Activation During Landing Before and After Fatigue in Individuals With or Without Chronic Ankle Instability
Webster 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.
Questions 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?
Written by: Nicole Cattano
Reviewed by: Jeffrey Driban