The Influence of X-Factor (Trunk Rotation) and Experience on the Quality of the Badminton Forehand Smash

TLDR

No prior badminton studies have used full‑body 3‑D motion capture to quantify forehand smash kinematics. This study aimed to quantify forehand smash kinematics with a 15‑segment model, compare novice and skilled players focusing on trunk rotation, and identify key parameters that determine smash quality. Twenty‑four players (10 novices, 14 skilled) were recorded with a 10‑camera VICON MX40 system at 200 fps to capture full‑body kinematics, racket motion, and shuttlecock flight. Skilled players exhibited greater trunk rotation, which increased shuttlecock release speed by lengthening the pectoralis major and enabling a whip‑like proximal‑to‑distal sequence, indicating that training should target X‑factor integration to improve smash quality.

Abstract

Abstract No existing studies of badminton technique have used full-body biomechanical modeling based on three-dimensional (3D) motion capture to quantify the kinematics of the sport. The purposes of the current study were to: 1) quantitatively describe kinematic characteristics of the forehand smash using a 15-segment, full-body biomechanical model, 2) examine and compare kinematic differences between novice and skilled players with a focus on trunk rotation (the X-factor), and 3) through this comparison, identify principal parameters that contributed to the quality of the skill. Together, these findings have the potential to assist coaches and players in the teaching and learning of the forehand smash. Twenty-four participants were divided into two groups (novice, n = 10 and skilled, n = 14). A 10-camera VICON MX40 motion capture system (200 frames/s) was used to quantify full-body kinematics, racket movement and the flight of the shuttlecock. Results confirmed that skilled players utilized more trunk rotation than novices. In two ways, trunk rotation (the X-factor) was shown to be vital for maximizing the release speed of the shuttlecock – an important measure of the quality of the forehand smash. First, more trunk rotation invoked greater lengthening in the pectoralis major (PM) during the preparation phase of the stroke which helped generate an explosive muscle contraction. Second, larger range of motion (ROM) induced by trunk rotation facilitated a whip-like (proximal to distal) control sequence among the body segments responsible for increasing racket speed. These results suggest that training intended to increase the efficacy of this skill needs to focus on how the X-factor is incorporated into the kinematic chain of the arm and the racket.