Objective: This study aimed to validate the use of Inertial Measurement Units (IMUs) for quantifying trunk motion in wheelchair sports and explore the relationship between trunk motion, wheelchair mobility performance, and classification level in elite wheelchair basketball athletes.
Methods: Fourteen participants (seven elite wheelchair athletes and seven non-WC users) completed eight standardized wheelchair mobility tests. Trunk motion was measured using IMUs and compared with a 3D motion capture (MOCAP) system. Trunk kinematics and wheelchair performance metrics were derived and analysed for correlation in the elite wheelchair group.
Results: IMUs, especially those mounted on the upper back, showed excellent agreement with 3D motion capture data (ICCs > 0.90; RMSE < 8%). Mean trunk angle correlated with wheelchair linear velocity during manoeuvring and sprinting tasks (r > 0.75), highlighting the role of dynamic trunk use in enhancing propulsion. Additionally, trunk kinematics, particularly range of motion, mean tilt angle, and forward lean time, showed strong correlations with classification level (r > 0.79), especially during the straight push test. Performance metrics demonstrated weaker correlation with classification (r < 0.47), suggesting that impairment may not directly translate into measurable differences in mobility performance in this sample.
Conclusion: Trunk rotation angles derived from IMUs provide a valid and practical tool for measuring trunk motion. Their integration could support more transparent and impairment-focussed classification frameworks.