Research

Introduction: Longitudinal analyses of participants with a history of first-time lateral ankle sprain are lacking. This investigation combined measures of inter-joint coordination and stabilometry to evaluate eyes-open (condition 1) and eyes-closed (condition 2) static unipedal stance performance in a group of participants with chronic ankle instability compared to ankle sprain 'copers', both recruited 12-months after sustaining an acute first-time lateral ankle sprain. Methods: Twenty-eight participants with chronic ankle instability and forty-two ankle sprain 'copers' completed three 20-second single-limb stance trials in conditions 1 and 2. An adjusted coefficient of multiple determination statistic was used to compare stance limb 3-dimensional kinematic data for similarity in the aim of establishing patterns of inter-joint coordination. The fractal dimension of the stance limb center of pressure path was also calculated. Results: Between-group analyses revealed significant differences in stance limb interjoint coordination strategies for condition 1 and in the fractal dimension of the center-ofpressure path for condition 2. Participants with instability displayed increases in anklehip linked coordination compared to copers in condition 1 (sagittal/frontal plane: 0.15 [0.09] vs 0.08 [0.06]; η2 = 0.18) and a decrease in the fractal dimension of the centerof- pressure path during condition 2 (injured limb: 1.78 [0.11] vs 1.88 [0.10]; η2 = 0.17). Conclusion: Participants with chronic ankle instability present with a hip-dominant strategy of static unipedal stance and display reduced complexity of the stance-limb center of pressure path compared to ankle sprain copers, during eyes-open and eyes-