Vertical and shear impulses affecting racket speed in tennis serve

Abstract

A high-speed tennis serve offers a competitive advantage, with racket speed commonly serving as an indicator of serve performance and showing a correlation with ground reaction force (GRF). The maximum vertical GRF has been associated with serve performance; however, this measure reflects only a single value and does not capture the temporal dynamics of GRF generation by leg power. Impulse is a more appropriate variable for correlating with serve performance because it accounts for the duration of force application. Studies have shown that vertical impulse exhibits a weaker relationship with racket speed compared to anterior–posterior impulse. However, the medial–lateral direction may also correlate with racket speed because it contributes to trunk rotation and facilitates the transfer of kinetic energy through the upper limb to the racket. Therefore, this study investigated the relationship between racket speed, GRF in the vertical and shear directions, and trunk kinematics to better understand the kinetic chain during tennis serves. Ten experienced Thai tennis players were recruited to perform serves. Racket speed and force–time data were collected using motion capture cameras and two force plates, respectively. The results indicated that racket speed was more strongly correlated with shear impulse (r = 0.5021) than with vertical impulse (r = 0.1322). Linear regression analysis revealed that shear impulse was highly correlated with trunk kinematics, confirming the presence of a kinetic chain during the tennis serve. This finding can be applied in training sessions to improve serve performance. Tennis coaches and players can use this parameter as a target for optimizing training programs and improving overall serve effectiveness.