Effect of unplanned block in volleyball on joint coordination during landing

Abstract

Understanding joint coordination during landing is essential in volleyball, a sport requiring explosive movements and rapid transitions. This study investigates inter-joint co- ordination in the landing phase following a block, focusing on the effects of planned versus unplanned conditions and gender-related differences. Twenty volleyball players (10 male, 10 female), competing at national to professional level in Belgium, participated in a laboratory- based protocol involving three-step block jumps under both planned (known direction) and unplanned (direction revealed at movement onset) conditions. Kinematic data, ground re- action forces, and surface electromyography were recorded using a motion capture system, force plates, and wireless sensors. Joint coordination was assessed using classical biomechanical analysis, Principal Component Analysis, and Statistical Parametric Mapping. Minimal differences were ob- served between planned and unplanned landings, suggesting a shared global motor strategy. This may be due to the timing of direction cues and task constraints, such as the requirement to land on force plates. Sex differences were more pronounced. Female athletes showed more consistent, distal-joint-dominatedpatterns, whilemalesreliedmoreonproximaljointsanddemonstrated greater variability. Reaction forces analysis supported these trends, with females exhibiting smoother force profiles. A consistent asymmetry between lead and trail legs was observed, likely reflecting task-specific movement organization.