This study aimed to examine how key anterior cruciate ligament (ACL) injury risk indicators, including knee flexion angle, single-leg jump performance, landing forces, and jump-landing mechanics, change across three distinct seasonal phases (pre-season, beginning of the season, mid-season) in young female volleyball players. Twelve adolescent female volleyball players completed performance assessments at three time points. Single-leg countermovement jump (SLCMJ) height, peak landing force, knee flexion angle during landing, and Landing Error Scoring System ( LESS ) scores were recorded. Repeated measures comparisons were used to assess temporal changes. The pre-season period demonstrated the poorest performance profile: the lowest jump heights, the highest landing forces, reduced knee flexion angles, and the highest LESS scores. From pre-season to the beginning of the season, jump height increased significantly, while landing forces and LESS scores decreased. Knee flexion angles increased progressively across the season for both extremities, indicating improved neuromuscular control and safer landing mechanics. The high F land / h jump ratio observed in the pre-season suggests an unfavorable combination of high landing loads and low performance, reflecting a high ACL injury risk. Findings highlight the pre-season period as the most critical phase for ACL injury risk in young female volleyball players. Reduced neuromuscular performance, insufficient knee flexion, and higher landing loads converge during this time, increasing injury susceptibility. Coaches and practitioners should prioritize neuromuscular control, landing technique, and lower-limb strength balance in pre-season training. Future research with larger, multi-sport cohorts should further investigate the direct relationship between seasonal performance changes and injury incidence.
Demirel et al. (2026) studied this question.