Tennis movements are characterized essentially by lateral displacements, thus external load on the lower extremities is created predominantly by friction generated between shoes and playing surfaces. This study analyzed the behavior of frictional forces and torques produced during an open stance forehand using various playing surfaces and different sport shoes. The frictional data were obtained from 12 advanced players returning a tennis ball fired from a ball machine and hitting a large Kistler force plate located at the base line of the tennis court. Using statistical ANOVA techniques, friction was found to be more sensitive to the choice of playing surface than to the choice of tennis shoe. “Fluid” type surfaces displayed the lowest frictional values in most cases. Additionally, comparison of the frictional data collected during the forehand with the measurements from a standardized laboratory test demonstrated that extrapolation of friction results from laboratory to real field conditions may lead to erroneous conclusions.
The authors are with the Laboratory of Biomechanics, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.