在赛跑时，有的运动员为了加大步幅，往往有意向前甩小腿，使摆动腿的膝关节伸直，并以这个姿势消极地等待脚落地。这是错误动作。我们知道，摆动腿落地时，脚落在人体重心投影点的前方，此时支撑反作用力通过重心方向朝后上方，它分解成垂直分力与水平分力。垂直分力向上，抵? In the race, some athletes in order to increase the stride, tend to deliberately rejection of the lower leg, the swing leg knee extension, and in this position negative waiting for the foot fall. This is the wrong action. We know that the swing leg landing, the foot fall in front of the human body center of gravity projection point, this time supporting the reaction force through the direction of the center of gravity toward the top, it is divided into vertical component and horizontal component. Vertical force up, arrived?