Effects of lower limb biomechanical characteristics on jump performance in female volleyball players based on long Stretch-Shortening cycle movements.

Background: In volleyball, certain maneuvers (e.g., depth jumps) involve a long stretch-shortening cycle (long-SSC) characterized by a prolonged landing-to-takeoff phase (ground contact time ≥222 ms). However, the key biomechanical factors influencing jump height in such long-SSC movements remain unclear, particularly in female athletes. This study investigated depth jump biomechanics in female volleyball players to identify performance-related factors and inform training optimization. Methods: Eighteen trained female volleyball players performed maximal-effort depth jumps under 3D motion capture. Pearson correlation analysis examined relationships between biomechanical variables and jump height. Participants were then divided into high (HJG) and low (LJG) jump-height groups based on a median split and compared using independent samples Results: Jump height correlated positively with peak propulsion velocity, peak propulsion power, knee flexion-extension angle, peak ankle moment, and peak propulsion impulse (all Conclusion: Peak propulsion velocity was the strongest correlate of jump height in long-SSC depth jumps. Propulsion-phase variables, particularly ankle torque and impulse, were more influential than braking-phase variables. In contrast to short-SSC tasks, high lower-limb stiffness appears to provide limited benefit for maximizing performance in long-SSC movements. Training for female volleyball players should therefore prioritize developing propulsion-phase power and ankle strength for these types of jumps. Trial registration number: ChiCTR2400094392; Registration date: 22/12/2024.