Altered Ankle-Muscle Activation during Jump Landing in Participants with Functional Instability of the Ankle Joint

Context: Identification of motor control deficit associated with Functional Instability (FI) of the ankle joint. Objective: T o compare patterns of ankle muscle activation during jump landing in participants with FI and a control group. Design: Cross-sectional comparison. Setting: Research laboratory. Participants: Twelve participants with FI (6 m, 6 f; age, 26.4 ± 4.6 years) and 10 control subjects (5 m, 5 f; age 24.9 ± 2.5 years). Main Outcome Measures: Integrated electromyographic (IEMG) activity of ankle musculature in the 150-millisecond period immediately prior to and post impact during 2 different jump landing activities. Results: Participants with FI demonstrated a significant reduction in pre-impact peroneus longus IEMG activity during both jumping activities compared to controls ( P < .05). There were no significant differences between the groups’ soleus or tibialis anterior IEMG activity during the pre- or post-impact periods. Conclusions: These results help to further our understanding of changes in control of ankle movement during dynamic activity in participants with FI.