Impact of Modified Competition Formats on Physical Performance in Under-14 Female Volleyball Players: The Role of Biological Maturity

The present study aimed to examine the influence of different competition models on the physical performance of under-14 female volleyball players, attending to biological maturity development. A quasi-experimental design was conducted involving 29 regional-level players (mean percentage of predicted adult height [PAH] = 95.38%). Three tournament formats were implemented: Standard Tournament (ST) 1 followed official regulations; Modified Tournament 1 (MD1) featured modified rules including a reduced net height (from 2.10 m to 2.00 m), prohibition of jump serves, and a maximum of two consecutive serves per rotation; and Modified Tournament 2 (MD2) included all prior modifications alongside a reduced court size (from 9 × 9 m to 8 × 8 m). Performance metrics analyzed included the number of accelerations, decelerations, impacts, and jumps (total count, G-force, take-off, and landing characteristics). Measures were gathered using a local positioning system (LPS) device based on UWB technology and an inertial measurement (IMU; WIMU PROTM, Real Track Systems, Almeria, Spain). Significant differences were observed between the tournaments, with Modified Tournament 1 (MD1) and Modified Tournament 2 (MD2) showing higher values in accelerations (<i>p</i> = 0.005), decelerations (<i>p</i> = 0.005), impacts (<i>p</i> < 0.01), and jumps (<i>p</i> < 0.01) compared to Standard Tournament. Notably, the greatest improvements were found between Standard Tournaments (ST) and Modified Tournament 2 (MD2). These findings suggest that modified competition formats enhance kinematic performance in under-14 female volleyball players. The results support the need for age- and maturity-appropriate adjustments to competition regulations in youth volleyball.