Differences in knee-ankle configuration and ankle joint kinetic characteristics during a drop landing vertical jump task in highly trained male basketball players: a cross-sectional study based on rebound efficiency.

OBJECTIVE: This study compared contact-phase timing, knee-ankle configuration at the lowest center of mass (COM), and ankle-moment characteristics between basketball players with high and low drop landing vertical jump (DLVJ) rebound efficiency. METHODS: Forty-one highly trained male basketball players were classified as high (n = 21) or low efficiency (n = 20). Participants performed a 30-cm box DLVJ while three-dimensional kinematic and kinetic data were recorded. Between-group differences were tested using two-sided Mann-Whitney U tests with Benjamini-Hochberg false discovery rate (FDR) correction. Spearman rank correlations between rebound efficiency and biomechanical variables were examined in the full sample. RESULTS: The high-efficiency group achieved greater DLVJ height (p = 0.014, q = 0.027) and rebound efficiency (p < 0.001, q < 0.001), whereas relative squat one-repetition maximum did not differ (p = 0.235, q = 0.353). Contact, braking, and propulsive times were shorter in the high-efficiency group (all p < 0.001, all q < 0.001). At the lowest COM, knee flexion and ankle dorsiflexion angles were smaller (p < 0.001, q < 0.001; p = 0.006, q = 0.016, respectively). The high-efficiency group also showed a greater mean ankle moment during braking (p = 0.014, q = 0.027) and reached peak ankle moment earlier during braking (p = 0.002, q = 0.007) and propulsion (p = 0.007, q = 0.016). Peak ankle moment during braking and propulsion showed uncorrected between-group differences (both p = 0.046), but neither remained significant after FDR correction (both q = 0.079). CONCLUSION: Greater DLVJ rebound efficiency in highly trained basketball players was associated with shorter contact-phase durations, smaller knee flexion and ankle dorsiflexion at the lowest COM, and earlier ankle-moment timing during landing-to-repropulsion. These differences were not accompanied by higher relative maximal squat strength, suggesting that rebound efficiency reflects task-specific landing-transition characteristics rather than maximal lower-limb strength alone. Because contact time is included in the rebound-efficiency calculation, temporal findings should be interpreted as component characteristics, not independent outcomes. Knee-ankle configuration and ankle-moment timing may offer task-specific observational information on distal ankle-joint kinetic involvement during DLVJ performance.