Developmental changes of vertical jump performance in young female basketball and volleyball players: A Bayesian multilevel modeling approach

This study examined developmental trajectories of vertical jump performance in young female basketball and volleyball players using Bayesian multilevel modeling. Eighty-one Brazilian female athletes (basketball: n = 46; volleyball: n = 35) aged 11-18 years were assessed between 2016-2024 in a mixed longitudinal design. Models examined longitudinal age-related changes in countermovement jump performance, sport-specific differences, and body size effects. Results showed non-linear developmental patterns with accelerated improvement during early-to-mid adolescence followed by deceleration. Sport differences emerged in baseline performance levels rather than timing. Age effects strengthened after adjusting for body size ( β age = 0.25, 68% credible interval [CI]: 0.17, 0.34; β age 2 = -0.18, 68% CI: -0.28, -0.08), indicating neuromuscular adaptations distinct from increases in body size. Body mass negatively associated with jump performance ( β body mass = -0.35, 68% CI: -0.44, -0.25), while stature positively associated ( β s t a t u r e = 0.20, 68% CI: 0.10, 0.29). Volleyball players demonstrated lower baseline performance than basketball players ( β v o l l e y b a l l = -0.35, 68% CI: -0.43, -0.27). Substantial between-athlete variability in baseline performance ( σ i n t e r c e p t = 0.31) suggests limited predictive validity of early assessments. Our findings provide substantial female-specific evidence for developmental patterns in youth team sport athletes and demonstrate the utility of Bayesian methods for handling incomplete longitudinal data.