Control of horizontal movement of mass center of body and center of pressure in vertical jumps

抄録

The role of horizontal component of the ground reaction force (GRF) in the motion control of vertical jump was investigated. Eight male subjects performed two types of counter movement jump. One was free maximal-effort counter movement jump (Type F). The other was the maximal-effort counter movement jump, with heels kept off the floor (Type H). In this case, contact between the foot segments and the floor was restricted. GRF was recorded with a force platform. Location of the center of pressure (COP) and movement of mass center of body (MCB) were calculated. In both types, negative (anterior-posterior direction) value of horizontal component of GRF was observed just before the take-off. For both MCB and COP, horizontal movement was larger in Type F than in Type H. In order to jump vertically, MCB has to be located mechanically just above COP at the instant of take-off. As the negative horizontal force acted on the MCB and stopped its forward motion just before take-off especially in Type F, the location of the COP and the MCB were consequently synchronized at the take-off. There is a possibility that assumptions about the interface between foot and ground, presented in preceding simulation studies are somehow simplistic.