テニスラケットのスピン性能のメカニズム

ストリング交差点潤滑によるスピン性能向上の超高速ビデオ画像解析

抄録

Players often say that some strings provide a better grip and more spin than others, but ball spin did not depend on string type, gauge or tension in the past laboratory experiment. There was no research work on the spin to uncover what is really happening during actual tennis impact owing to difficult experiment. This paper made clear the mechanism of top spin and its improvement by lubrication of strings according to the high speed video analysis. It also provided the more detailed explanations of spin behavior by comparison between a lubricant string racket and a famous 'Spaghetti strings racket' which was banned in 1978 by the International Tennis Federation since it used plastic spaghetti tubing over the strings to reduce friction resulting in the excessive spin on the ball. As the main strings stretch and slide side ways more, the ball is given more spin due to restoring force parallel to the string face when the main strings spring back and the ball is released from the strings. Furthermore, it showed that the more spin results in the reduction of shock vibrations of the wrist joint during impact.