PURPOSE Repetitive lateral ankle sprains often cause chronic ankle instability (CAI) leading to various sensorimotor deficits. This study aimed to investigate altered ankle dorsiflexion force control capabilities in individuals with CAI. METHODS Ten young adults with unilateral CAI performed isometric ankle dorsiflexion force control at 20% of the maximum voluntary contraction under vision and no-vision conditions. Participants executed submaximal force control tasks with their impaired and non-impaired ankles. To evaluate the force control capabilities, we estimated the force trend, accuracy, and variability. Two-way repeated-measures ANOVAs (ankle×vision, 2×2) for each force control variable were used for statistical analyses. RESULTS When the visual information was removed, a declining force trend was observed in the impaired ankle (p<.001), whereas no differences were observed in the non-impaired ankle (p=.096). In the no-vision condition, the impaired ankle showed a lower mean force (p=.035) and force accuracy (p=.009) and greater force variability (p=.004) than the non-impaired ankle. CONCLUSIONS These findings suggest that CAI interferes with ankle dorsiflexion force control without visual information, indicating sensorimotor impairment
