Difference in response latency of the peroneus longus between the dominant and nondominant legs.

CONTEXT The latency of the peroneus longus in response to an inversion perturbation is a key component in the prevention of lateral ankle sprains. In addition, the dominant ankle is sprained more frequently than the nondominant ankle, but the cause of this has not been examined. OBJECTIVE To investigate the combination of these 2 research-supported statements, the purpose of this study was to use an inversion perturbation that replicates the mechanism of a lateral ankle sprain to determine whether there is a difference in the latency of the peroneus longus between the dominant and nondominant legs. DESIGN Repeated-measures single-group design. SETTING University laboratory. PARTICIPANTS 15 physically active healthy volunteers with no previous history of an ankle sprain or lower extremity surgery or fracture. INTERVENTIONS Outer sole with fulcrum was used to cause 25° of inversion at the subtalar joint on landing from a 27-cm step-down task. Participants performed 10 trials on both the dominant and nondominant leg. MAIN OUTCOME MEASURES 2 latency measures of the peroneus longus of both the dominant and nondominant leg, calculated as the amount of time from the moment of touchdown of the fulcrum until muscle activity exceeded 5 and 10 SD above baseline muscle activity. RESULTS The latency of the peroneus longus of the nondominant leg was significantly shorter when using both 5 SD (F1,14= 9.34, P = .009, d = .895) and 10 SD (F1,14= 18.56, P = .001, d = .920) above baseline muscle activity. CONCLUSIONS This difference in latency may be a result of the different demands placed on the dominant and nondominant legs during activity and may predispose the dominant ankle to a greater number of ankle sprains than the nondominant ankle.