Landing models for volleyball players: a longitudinal evaluation.

The purpose of the study was to longitudinally evaluate lower extremity landing performance of elite volleyball players. Seven female members of a Division 1 NCAA volleyball team completed three data collection sessions (pre-, post-, off-season) during which they performed block-jumps on a dual force platform system (1000 Hz) while being simultaneously videotaped from the right sagittal view (200 Hz). Selected kinetic and lower extremity kinematic variables were calculated. Three dependent variables representing landing impact were identified: first (F 1) and second (F 2) maximum vertical force and knee joint range of motion (K(ROM)). A non-landing performance measure, jump height was also evaluated. Results of repeated measures univariate ANOVAs identified a significant (p < 0.05) difference for test session for K(ROM) suggesting a kinematic change in landing performance across the season. Multiple regression models to predict landing impact identified 88.1 and 98.3% explained variance for F1 and F2 with no significant K(ROM) model identified. F1 was predicted by ankle joint angular velocity during the jump while F2 was best predicted by jump phase braking impulse. Application of the group prediction equations to individual athletes produced differential results across subjects, suggesting the need to tailor the model to the athlete. The results further suggest training/practice-related kinematic differences and have implications for training and assessment of individuals who perform dynamic landing activities.