## 網球第二發球之運動學分析(以上旋式及側旋式為例) Kinematic Analysis of Tennis Top Spins and Side Spins Second Serves

2005

Jiun-Cheng Lin
##### Abstract

In a tennis game, serving was one of the most important skills as well as the major strategy to gain points. The second serve plays an important role in a game, too. A correct second serve can avoid not only the loss of points but also an inferior situation. In this study, a Redlake high-speed (250Hz) camera was used to record the top spins and side spins of second serves made by ten first-rate college tennis players in Taiwan, and a two-dimensional kinematical analysis was made on these serves. The purpose was to examine different kinematic variables that may affect the second serve, to understand the influence the style of the serve may have on the precision and the speed of the ball, and to find out a better way of doing a second serve, which can be a reference to coaches and teachers in their instruction.In the experiment, the players were asked to do 5 second serves into an assigned area, the fastest which was chosen to be compared in terms of the player’s postures. The data were calculated and analyzed through the statistical software kwon3D 3.0 and SPSS Paired-Samples t-Test, a=.05. The results were as following: 1. Neither the impact height nor the precision of the serves was significantly different. 2. In terms of the speed after the ball was hit, side spin second serves (32.93m/s) were faster than top ones (30.92m/s) (P< .05). 3.As for the angular velocity and resultant velocity of the joint of the forearm: (1) In terms of the angular velocity of the joint of the shoulder, side spin serves were faster than top spin ones. There were also higher averages (of angular velocity) in the joints of the elbow and the wrist in side spin serves. (2)There was no significant difference in the resultant velocity of the shoulder joint between side spin and top spin serves. (3)The resultant velocities of the elbow joints andthe wrist joint were 4.09m/s and 7.0m/s respectively in side spin serves, which were significantly different from those in top spin serves, 3.7m/s and 5.72m/s.The conclusions of this study were as following: In kinematics, side spin serves has faster angular velocity and resultant velocity, so that it can produce a higher speed in serving. Besides, side spin serves has a higher average of precision. Therefore, Players can adopt more side spins in the tennis games.