Influence to a wrist joint by the topspin technology in tennis

本研究旨在探讨上旋球挥拍时手与前臂的姿势，以减少上旋球对手腕的伤害。测量了上旋球拍挥动过程中腕关节的角度，比较了东西方握拍方式下腕关节欧拉角的差异。另一方面，测量腕关节3个轴的圆周最大扭矩，并与实际挥动球拍时的最大扭矩进行比较。并且这些力矩在握杆角度上也相差不大。但与欧拉角相比，东方握法以桡侧屈曲为主，西方握法以旋前为主。旋前有很大的灵活性，也比桡侧屈曲有更大的力量。这意味着西方的握拍方式有可能减少受伤。

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.