Activities of the intrinsic muscles of the foot and lower leg during a single-leg stance and drop landing in individuals with chronic ankle instability

Abstract

Objectives: The aim of this study was to compare intrinsic foot muscle activity during single-leg standing and single-leg drop landing between participants with and without chronic ankle instability. Design: A cross-sectional study. Setting: Laboratory. Participants: Twelve participants with chronic ankle instability and eleven control participants. Main outcome measures: The main outcomes were the muscle activities of the abductor hallucis, abductor digiti minimi, peroneus longus, and soleus muscles and the center of pressure during single-leg standing and single-leg drop landing. Results: Participants with chronic ankle stability showed increased soleus muscle activity during single-leg standing with eyes closed and after single-led drop landing compared with that of controls. In the chronic ankle instability group, lower Cumberland Ankle Instability Tool scores were associated with reduced abductor digit minimi muscle activity during landing. No significant differences were found in other outcomes. Conclusions: Reduced abductor digit minimi muscle activity may be associated with greater severity of chronic ankle instability. Increased soleus muscle activity in individuals with chronic ankle instability may serve as a compensatory mechanism for other impairments during single-leg standing with eyes closed and single-leg drop landing tasks.