Professional tennis players' serve: correlation between segmental angular momentums and ball velocity

Abstract

The purpose of the study was to identify the relationships between segmental angular momentum and ball velocity between the following events: ball toss, maximal elbow flexion (MEF), racket lowest point (RLP), maximal shoulder external rotation (MER), and ball impact (BI). Ten tennis players performed serves recorded with a real-time motion capture. Mean angular momentums of the trunk, upper arm, forearm, and the hand-racket were calculated. The anteroposterior axis angular momentum of the trunk was significantly related with ball velocity during the MEF–RLP, RLP–MER, and MER–BI phases. The strongest relationships between the transverse-axis angular momentums and ball velocity followed a proximal-to-distal timing sequence that allows the transfer of angular momentum from the trunk (MEF–RLP and RLP–MER phases) to the upper arm (RLP–MER phase), forearm (RLP–MER and MER–BI phases), and the hand-racket (MER–BI phase). Since sequence is crucial for ball velocity, players should increase angular momentums of the trunk during MEF–MER, upper arm during RLP–MER, forearm during RLP–BI, and the hand-racket during MER–BI.