Comparison of Knee Kinematics and Muscle Activity of the Lower Extremities between Single and Double Leg Drop Landing

Purpose) The purpose of this study was to determine the effect of two different drop landing tasks on knee kinematics and muscle activities. (Subjects) Nine healthy males participated in this study. (Methods) The subjects performed two different drop landing tasks from a box (height, 30 cm), with the dominant leg and both legs. A motion analysis system was used to obtain knee valgus and maximal flexion angles in the frontal and sagittal planes. An elec- tromyography system was used to record muscle activities of the lower extremities during the drop landing task. (Results) Single leg landing increased the knee valgus angle, decreased the knee flexion angle, and increased the activ- ity of the lower extremity muscles as compared to double leg landing. (Conclusion) Increased knee valgus angle and decreased knee flexion angle with single leg landing may be related to the increased risk of anterior cruciate ligament