Comparative kinematic analysis of the upper extremity during the backhand topspin loop between elite table tennis players Lin Shidong and Xiang Peng

The transition to the 40 + mm ABS ball era has significantly increased the biomechanical demands on elite table tennis players, establishing the backhand topspin loop as a critical offensive weapon. This study aims to quantify the kinematic differences between the “optimal template” represented by Lin Shidong and the high-power yet structurally inconsistent technique of Xiang Peng. Utilizing a synchronized 200 Hz high-speed dual-camera system and Simi Motion 9.2.2 3D analysis, ten high-quality stroke cycles were analyzed for each athlete. Statistical analysis via independent sample T-tests revealed that Lin Shidong utilizes a more efficient rhythmic structure, characterized by a significantly longer backswing (0.481 ± 0.074 s) to optimize the stretch-shortening cycle (SSC) compared to Xiang Peng (0.378 ± 0.031 s, p < 0.01). While Xiang Peng achieved higher absolute peak racket velocity (14.686 ± 0.609 m/s vs. 11.684 ± 0.762 m/s), Lin Shidong demonstrated a significantly superior velocity utilization rate at impact (93.89% vs. 88.43%, p < 0.05). Joint kinematics indicated that Lin Shidong adheres to the “proximal stability for distal mobility” principle, 1 maintaining a stable shoulder fulcrum while executing an explosive elbow extension (70.02° to 78.42°) and terminal wrist snap. Conversely, Xiang Peng's mechanics displayed excessive shoulder horizontal flexion and a “locked” elbow, leading to premature acceleration and energy dissipation. These findings suggest that elite backhand proficiency depends on rhythmic regulation and terminal segmental coordination rather than raw speed. Technical optimization for high-power athletes should focus on enhancing the “whipping effect” through improved proximal stability and distal flexibility.