An investigation to determine the kinematic variables associated with the production of topspin in the tennis groundstrokes.
Doctoral thesis, University of Central Lancashire.
The ability to impart topspin to the ball when playing forehand and backhand groundstrokes can give a tennis player a tactical advantage in a rally. Recent developments in racket technology and tactical approaches to the game have increased the prevalence of topspin strokes. However, there is a limited scientific knowledge base for players and coaches to draw upon when seeking to improve this aspect of the game. Many of the kinematic analyses into tennis groundstrokes were conducted more than ten years ago, with measurement techniques that may not have accurately measured the anatomical rotations important for generating racket velocity. It has only recently been possible to measure the spin rate of a ball, and this has not been investigated in relation to the kinematics of a player. This study aimed to make an important contribution to the knowledge of tennis professionals by establishing which kinematic variables are related to the production of high ball spin rates resulting from topspin strokes. In order to achieve this aim, consideration was given to the accurate measurement of the joint rotations of the player in all planes of movement and the quantification of the ball spin rate. This information was used to answer three further questions; what are the kinematic differences between flat and topspin groundstrokes, how do these differences relate to the spin rate of the ball and how do these findings relate to individual players? Joint rotations were calculated based on three-dimensional data captured from twenty participants playing flat and topspin forehand and backhand strokes. The resulting ball spin rate was captured using a high-speed camera. The participants produced larger ball spin rates when playing the topspin strokes, indicating that they were able to produce spin if required. Analysis of the joint rotations revealed that there were adaptations in the stroke in order to achieve the higher spin rates. The adaptations were not uniform among participants, but did produce similar alterations in racket trajectory, inclination and velocity for the topspin strokes. It was these measures that were found to be the strongest predictors of ball spin rates, accounting for over 60 % of the variation in ball spin rate in the forehand stroke and over 70% in the backhand. Case study analyses confirmed the importance of the optimal racket kinematics at impact and provided models of technique throughout the forward swing of each stroke. This study has made a contribution to the knowledge of generating topspin in the tennis groundstrokes by establishing the parameters that predict high spin rates and applying them to analyses of individual players. In doing so, this investigation has also demonstrated methodology that is capable of accurately measuring the joint rotations associated with tennis strokes, and suggested a method by which the spin rate of the ball can be calculated.
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