MECHANICAL ENERGY FLOW OF THE TRUNK IN TENNIS SERVE

The purpose of this study was to investigate the mechanical energy flow of the trunk during tennis serve. Three-dimensional coordinates of the players performing flat, kick, and slice serves were collected. The findings were summarized as follows.1) Regardless of the spin characteristics, the mechanism that right arm acquires the mechanical energy is almost same. 2) It is important to rotate the trunk as fast as possible, when the more mechanical energy flows from the trunk to the right arm more. 3) The roles of both legs are different from the viewpoint of energetics. The lower trunk aqcuired the translational energy from the left leg mainly, and the rotational energy from the right leg mainly. And it is guessed that player selects preferentially not to flow the more mechanical energy to right arm but to swing a racquet appropriately (to generate a ball spin)