Asymmetry of lower extremity responses to external impact loading

Abstract

The purpose of this study was to determine if the lower limb cushioning responses to impact loading were asymmetrical. A human pendulum was used to quantify impact loading and the shock wave that traveled through the locomotor system. Twenty-four healthy adults impacted a wall mounted platform 40 times with each foot while their leg was flexed 20 deg at the knee. Time and frequency analyses were performed, asymmetry was expressed according to a lower limb strength dominance index. No statistical differences were found between dominant and non-dominant limbs, however, histogram representations of the results revealed that 65 percent of the subjects responded asymmetrically. The asymmetry could not be linked to leg strength dominance. The magnitude and high incidence of asymmetrical responses under controlled inital lower limb kinematics suggested that the contribution of the lower limbs' structural properties and levels of muscular activation to bilateral asymmetry could be paramount during locomotion.