有人把攻球动作中的重心和腰的运动方式理解为类似于一扇门的转动,说门是围绕一个轴转的,而我们攻球动作中的这个轴就是我们身体的中轴,因此腰和重心都是在围绕这个“轴”运动出一条扇形轨迹。持此论者还举出了雨伞的转动使雨水向四处飞溅和链球在运动员身体加速旋转后飞向远方的例子来说明自己的观点,并把这种门轴式的动作称之为“圆周运动”。 Some people think that the center of gravity and lumbar movement in the attacking action is understood to be similar to the rotation of a door, saying that the door is rotated about one axis. The axis in our attacking action is the central axis of our body. Therefore, And the center of gravity is moving around this “axis ” out of a fan-shaped trajectory. The commentator also cites an example of an umbrella’s rotation that splashes the rain around and the chain-ball flew afloat as the athlete’s body spins and calls this door-axis motion a “circle movement”.