Lower Extremity Asymmetries during Jump-landing Tasks

Higher side-to-side asymmetry among female athletes compared to their male counterparts during bilateral athletic tasks such as landing from a jump has been proposed as a potential source of non-contact knee injuries. However, the kinematic symmetry and potential sex differences during bilateral landings have not been examined. The purpose of this study was to evaluate lower extremity kinematic symmetry in 13 male and 15 female athletes during maximum forward jump-landings (FL) and drop landings (DL). Knee valgus (p=0.006) was more asymmetrical during FL than DL and a similar trend was demonstrated for hip adduction (p=0.057). A trend was found for females landing with greater knee valgus asymmetry during FL (p=0.078) and with greater ankle abduction asymmetry during DL (0.091). The greater asymmetry during landings exhibited by female athletes may add to the biomechanical factors that have been identified as responsible for the higher rate of knee injuries among females and may assist in the development of injury prevention programs. As some of the sex differences were apparent in one landing task but not in the other, the importance of testing a variety of athletic tasks in the laboratory is emphasized.