Interplay Between Postural Stability and Coordination in Female Soccer Players With Chronic Ankle Instability

OBJECTIVE: This study investigated the effects of chronic ankle instability (CAI) on postural control following landing with an unanticipated task and on shank-rearfoot coordination during side-cutting in female soccer players. The association between postural stability and coordination patterns was investigated to identify shared control characteristics across tasks. METHODS: Eighteen female soccer players were categorized into CAI (n = 10) and control (n = 8) groups. Participants performed 20-s single-leg stances and side-cutting following landing with an unanticipated task. Postural control during single-leg stance was quantified using the largest Lyapunov exponent of the mediolateral center of pressure. Shank-rearfoot coordination during side-cutting was analyzed using a modified vector-coding technique. RESULTS: The CAI group exhibited a significantly lower largest Lyapunov exponent of mediolateral center of pressure during single-leg stance (p = .043). During side-cutting, the CAI group demonstrated an increased proportion of in-phase with distal dominancy during the deceleration phase (p = .027). Within the CAI group, largest Lyapunov exponent was associated with coordination patterns, where a negative correlation with anti-phase with proximal dominancy and a positive correlation with in-phase with distal dominancy (r = -.680 and .648, respectively; p < .050) were observed. CONCLUSION: Female soccer players with CAI exhibit reduced adaptability to postural control following landing with an unanticipated task and diminished flexibility in shank-rearfoot coordination during sport-specific cutting. The observed association between static postural instability and altered dynamic coordination may reflect a reduced capacity to flexibly modulate control strategies in patients with CAI, which may be related to the risk of recurrent ankle sprains.