Kinematic relations between first and second serve in tennis

Introduction The ball displacement, the racket (R) and ball post-impact velocity (v) in first (F) and second (S) serves were analysed by [1]. The aren’t studies about the body displacement as regards the R. The aim of this study is to find the differences between the F and S serve about the ball and R kinematics data and body positions. Methods 4 right-handed subjects (age 17,5 ±7; 450 ATP 4.4 NR) performed 16 serves. The best F and S serve (qualitative ob.) from left to right were analysed. 3 50Hz cameras were located outside the court. The serve area was calibrated. Simi Motion Analysis Syst. was used for a manual digitalization to obtain 3D coordinate data. We digitized 28 points (body, R, ball). Exel, Matlab and Spss were used to draw up the data. The determination of the instant of impact were made by [2]. Results The linear ball v at impact are significant (Freidman T.