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Published on: July 7, 2016
Disruption of Ankle Control Strategies by Exercise-Induced Fatigue During Stair Descent in Athletes With Chronic
Ansheng Wang1, Hang Qu2, Liangsen Wang1
1School of Physical Education, Shaanxi Normal University, Xi'an, China.
Objective:
To investigate how fatigue impacts the ankle control strategy of athletes with chronic ankle instability (CAI) during stair descent.
Design:
Case-control study.
Settings:
Sports Biomechanics Laboratory.
Participants:
A total of 50 male athletes (N=50) (25 CAI and 25 non-CAI) were recruited.
Interventions:
Not applicable.
Main Outcome Measures:
Ankle joint angle and torque in inversion/eversion, internal/external rotation, and dorsiflexion/plantarflexion, and EMG root mean square (RMS) values of the medial gastrocnemius, tibialis anterior, and peroneus longus.
Results:
Pre-fatigue, athletes with CAI showed larger maximum eversion angle and dorsiflexion torque (PFDR<.05) and lower medial gastrocnemius RMS (PFDR<.05), whereas fatigue caused athletes with CAI to increase maximum inversion and plantarflexion torque (PFDR<.05); maximum eversion torque, tibialis anterior, and peroneus longus RMS decreased (PFDR<.05).
Conclusions:
Pre-fatigue, athletes with CAI may adopt a compensatory protective strategy centered on an "excessive ankle eversion-dorsiflexion." However, fatigue disrupted this protective strategy, as reflected in a shift toward an "inversion-plantarflexion" pattern. These findings reveal that fatigue dismantles a key protective motor strategy in athletes with CAI during a common daily task. This highlights the need for clinicians and trainers to incorporate targeted endurance training for ankle evertor and dorsiflexor muscles to prevent reinjury.
