Quantification of lower limb joint function during acceleration phase of cutting maneuvers

Abstract

Side-step cutting maneuvers (SS) is one of crucial techniques in ball games. Since previous studies reported that running speed increase during the cutting maneuvers in the ball games (e.g. soccer), the purpose of this study was to quantify the functional roles of support leg joints during accelerating phase of SS. A male participant was instructed to do 90-degree SS under two types of approaching velocity conditions (i.e. 3.5m/s and 5.5m/s). Forty-seven reflective markers attached on the body and ground reaction force (GRF) of support legs were measured with Vicon-MX motion-capture system and force platform, respectively. The dynamic contributions of support leg joint torques, at first step (first cutting leg: CL1) and next step (CL2) during cutting maneuvers, to the generation of GRF were quantified by using dynamical force equation regarding 15-segment-linked whole-body system. The results obtained in this study show 1) regardless of the approaching velocities, the extension torque at knee joint of CL1 play a role in braking along the approaching direction, and the roles of the ankle plantar flexion torque of CL1 and CL2 in addition to the eversion torque of CL1 were braking along the approaching direction as well as propulsion along the cutting direction, 2) the total time integration of contributions, induced by the support leg joint torques of CL1, to the propulsive force along the cutting direction under the condition of 3.5m/s were larger than that of 5.5m/s, and 3) the inversion torque at ankle joint of CL2 play a role in braking along the approaching direction and propulsion along the cutting direction.