Abstract
The purpose of this study was to examine foot grounding by investigating how ground reaction forces and leg motions at grounding vary as velocities increase from walking through sprinting speeds. The participants were 3 male university students. They moved along a 12 m straight course at 6 velocities from walking to sprinting, and stepped on a force platform along the way. Three high-speed cameras synchronized to a video counter recorded their legs and feet as they moved. The velocities of movements and motion parameters were calculated by two-dimensional direct linear transformation method. The results were as follows. (1) The tendency for toe grounding increased with greater velocity. (2) As the tendency for toe grounding increased, the grounding time became shorter and the leg swing velocity increased. (3) At grounding, the knee joint angle decreased with increasing velocity. Regardless of the movement velocity, the ankle joint angle was 90° to 100°.
