The purpose of this pilot study was to investigate the correlation between the stiffness of tennis racket and the coefficient of restitution(COR).The tennis racket was fixed in a clamp and the tennis ball was controlled to hit the racket with a vertical impact at certain speed(approximate 20m/sec). NAC high speed camera (1000 frame/sec) was used to record the whole experimental procedure. The video tape was then digitized using Peak Performance System After statistical analysis, the results showed: The COR of high stiffness racket (stiffness=70)、medium stiffness racket(stiffness=60)and low stiffness racket (stiffness=50)are 0.604, 0.546, 0.472, respectively. According to the ANOVA, the COR of different stiffness rackets are significantly different (stiffness 70＞stiffness 60＞stiffness 50).
- Tennis racket