The Impact of Ground Reaction Force and Joint Kinematics on the Tennis Serve of Collegiate Players

Abstract

Purpose: The serve plays a key role in determining the outcome of a match but its complexity means it is one of the most difficult shots in tennis. Due to the paucity of research involving the interaction of the leg drive and upper limbs in the tennis serve, the aim of the current study was to examine how ground reaction force and joint kinematics influence service motion in collegiate players. Methods: Three-dimensional data was reconstructed using the direct linear transformation (DLT) method. Three flat serves of eight collegiate male players were recorded from two laterally placed cameras operating at 50 Hz. Ground reaction force (GRF) data was collected using a Kistler 5233A force plate operating at 1000 Hz. Group means and standard deviations were reported for each of the parameters measured. Results: An effective leg drive consisting in peak front and rear knee flexion angles of 69.2° and 78.5° respectively assisted in generating a ground reaction force (GRF) of 2.26 BW. As the shoulder was driven vertically at a maximum velocity of 2.68 m/s, the racket was positioned down behind the back with a velocity of -5.23 m/s. An efficient proximal to distal sequencing culminated at the wrist producing a mean resultant racket head velocity of 31.06 m/s and a subsequent resultant ball velocity of 36.14 m/s. Discussion and conclusion: The leg drive has a dual role of initiating the kinetic chain and preparing the racket for the forward swing. By better coinciding the time of maximum vertical hip velocity with the rackets maximum downward velocity, the racket can accelerate over a greater distance to impact. While service speeds were lacking compared to other collegiate performers in previous studies, an effective leg drive and functional kinetic chain provide a solid foundation for the serve to be developed in training.