ABSTRACT

The performance of a tennis racket is best evaluated when a person grips a racket, as this is closest to actual conditions of use. The vibration of a tennis racket has also been measured while suspending a racket using lines or while fixing it using a vice. However, such an approach ignores the physiological reactions of the human involved, and does not allow investigation of the mechanics of sports injuries such as tennis elbow. One attempt to remedy this involved building a non-rigid robot that could change the strength of its grip (Herbert, 1998), but more often human subjects are used. Kawazoe et al. (2001) have evaluated the vibration characteristics of hand-held rackets using a mood analysis. Furthermore, using this evaluation, they have optimized the racket vibration on impact by an actual hitting experiment and a simulation (Kawazoe & Tanahashi, 2002; Kawazoe et al. 2002). EMG (Electromyography) has frequently been used to measure muscle activity in an actual hitting experiment (e.g. Kuriyama, 1983). However, as the natural frequency of EMG is different from that of the vibration, EMG could not be measured in parallel with a physical element like vibration, using one unit.