100m走の加速局面における前傾姿勢の保持を意識する時間の違いが前傾角度，疾走速度，ピッチ，ストライドに及ぼす影響

The purpose of this study was to clarify the effect of the differences in time length of consciousness keeping the lean position in the acceleration phase of 100 m sprint on running velocity, stride frequency, and stride length. In this study, nine male collegiate sprinters ran 100 m sprint with three acceleration methods. The first method is the acceleration keeping their lean positions consciously during normal time (Normal Method: NM). The second and the third methods is the acceleration keeping their lean positions consciously during shorter and longer times than NM respectively (Shorter Method: SM, Longer Method: LM). Experimental trials were recorded by four high-speed cameras (300 fps) and one digital video camera (30fps). Forward angle, running velocity, stride frequency, and stride length in the acceleration phase and 0 m―100 m running velocity, stride frequency, and stride length were calculated. The results were as follows: 1) Forward angle of SM was smaller and forward angle of LM was larger at the 5 m, 10 m, 20 m, and 30 m. 2) 0 m―30 m, and 0 m―40 m running speed with LM were higher than that of SM. 3) There were no differences in stride frequency and stride length among the three acceleration methods. These results indicated that the differences in time length of consciousness keeping the lean position changed movement of the lean position in the acceleration phase, and as the result, the change affected running velocity.