The lateral ankle sprain is the most common athletic injury, and many people who suffer an ankle sprain develop chronic ankle instability (CAI). The purpose of this study was to examine the ground reaction force during a simulated lateral ankle sprain among participants with no history of ankle injury and those with CAI. Twelve participants, which included six with CAI, and six with no history of ankle sprain performed 14 repetitions of a vertical drop down off a 27 cm box, landing on an AMTI force platform. Seven trials were completed with a fulcrum outer sole strapped to the bottom of the participant’s shoe, which caused 25° of inversion upon landing, and seven trials were performed with a flat outer sole. Outer sole assignment was randomized. Peak vertical, anterior/posterior, and medial/lateral ground reaction force, normalized to multiples of body weight (BW), were measured for each participant. Results revealed that the no injury group landed with significantly greater (P< .05) peak vertical and peak anterior/posterior force than the CAI group. These differences in force between the two groups may be an attempt by the CAI participants to change loading of the unstable ankle, and the altered landing kinetics potentially increase future risk of injury.
Listed In: Biomechanics, Sports Science