Biomechanical differences between individuals with chronic ankle instability, copers and healthy controls in the countermovement jump on the force plate

To evaluate the counter-movement jump task in chronic ankle instability (CAI), copers and healthy subjects. Seventy-five subjects (25 CAI, 25 coper and 25 healthy) participated in the present study. Time to stabilization (TTS) and dynamic postural stability index (DPSI) after counter-movement jumplanding task on a force plate in both legs of each participant were assessed. To compare those three groups, One-way Analyses of Variance (ANOVA) with Tukey post hoc test was used. Pair t-test was utilized to demonstrate the probable changes within group. Using one-way Analyses of Variance (ANOVA) with Tukey post hoc testing, the CAI group displayed significant difference in the medial/lateral (ML) TTS and also DPSI in the vertical plane, and in the composite score than the healthy and coper groups. No significant difference was found between dominant and non-dominant legs in each group based on Pair t-test. Significant different dynamic postural stability was demonstrated in CAI group compared with copers and healthy control. It can be suggested that dynamic postural control strategies should be take into account in their rehabilitation programs. No difference between landings on dominant or nondominant leg can suggest central mechanisms for functional ankle instability.