Abstract
The purpose of this study was to quantify the functional roles of the swing leg joints during maximal velocity phase in sprint motion based on multi-body dynamics. Five male sprinters (height: 1.74±0.03m, body mass: 66.6±4.7kg, personal best time in the 100m: 10.9±0.27s) from a university track team performed 60m maximal sprints on a straight track in this experiment. Video data were recorded using three high-speed digital cameras (EXILIM-EX-F1, CASIO) operating at 300fps. Two dimensional kinematic and kinetic data of the participants sprinting around 50m were analyzed by using the trajectory of 25 landmarks of the body. In order to quantify the roles of primary joints such as hip and knee joints, which exert large joint torque, ankle joint input was treated as angular acceleration instead of joint torque. The results indicated that 1) this method enabled us to quantify the joint function of the swing leg in sprint, 2) the main generating factor of the swing leg motion was hip joint torque, and 3) ankle joint torque was necessary to control the orientation of the foot segment.
