Influence to a wrist joint by the topspin technology in tennis

本研究的目的是澄清在上旋球挥拍过程中手和前臂的姿势，以减少上旋球击球时手腕的损伤。测量了上旋球挥拍时手腕关节的角度，比较了西方握法和东方握法的欧拉角差异。另一方面，测量了腕部关节3轴圆周的最大扭矩，并与实际挥动球拍时的扭矩进行了比较。这些扭矩即使在西部和东部的抓地力角度上也相差不大。但与欧拉角相比，东方握法以径向屈曲为主，西方握法以旋前为主。旋前有很大的柔韧性，也比桡骨屈曲有更大的力量。这意味着西方握法有可能减少伤害。

The aim of this study is to clarify the posture of hand and forearm during the topspin racket swing and to reduce the wrist injury that occurs by hitting topspin. The angle of wrist joint during the racket swing of topspin was measured, and the difference of Euler angles between the western grip and eastern grip was compared. On the other hand, maximum torque of circumference of 3 axes of wrist joints was measured, and it compared with that of actually swinging a racket. And these torques differ little even in the grip angle of western and eastern. But comparing the Euler angle, eastern grip uses radial flexion and western grip uses the pronation mainly. The pronation has much flexibility and also it has much power than radial flexion. That means the western grip has possibility to reduce the injuries.