Abstract / Summary
Abstract Background and Objective: Volleyball is a high-demand sport requiring precise coordination among different body segments, effective postural control, and efficient force transmission throughout the kinetic chain. The trunk serves as the central axis for motor control and force transfer, playing an essential role in maintaining dynamic stability, performing sport-specific skills, and controlling landing patterns. Impaired trunk control may be associated with alterations in movement quality, landing mechanics and factors related to sports injury risk. The aim of this study was to investigate the relationship between trunk muscle endurance and static balance, dynamic balance, landing mechanics, and upper limb functional stability, as well as to compare these variables among female volleyball players with different levels of neuromuscular deficits based on the Tuck Jump Assessment. Methods: This analytical cross-sectional study was conducted on 60 adolescent female volleyball players (mean age: 16.4 ± 1.1 years). Participants were classified into two groups with higher and lower neuromuscular deficits (30 participants per group) based on the median score of the Tuck Jump Assessment. Trunk muscle endurance was assessed using the McGill Torso Muscular Endurance Test Battery, static balance using the Single-Leg Stance Test, dynamic balance using the Y Balance Test, landing mechanics using the Landing Error Scoring System (LESS), and upper limb functional stability using the Upper Quarter Y Balance Test (UQ-YBT). Between-group comparisons were performed using the independent-samples t-test for normally distributed variables and the Mann–Whitney U test for non-normally distributed variables , and Spearman's correlation coefficient was applied to examine relationships among variables. The significance level was set at P<0.05. Results: The results demonstrated significant associations between trunk muscle endurance and functional performance indicators, including static balance, dynamic balance, landing mechanics, and upper limb functional stability (P<0.001). The strongest correlations were observed between trunk flexor and lateral flexor endurance and functional performance measures (r=0.738–0.778, P<0.001). Other functional variables also demonstrated moderate-to-strong correlations with trunk muscle endurance (r=0.412–0.727, P<0.001). Between-group comparisons revealed that athletes with lower neuromuscular deficits demonstrated significantly better trunk muscle endurance, static and dynamic balance, landing mechanics, and upper-quarter functional stability than athletes with higher neuromuscular deficits (all P<0.001, effect sizes = 0.55–0.78). Conclusion: The findings indicate that trunk muscle endurance is associated with postural control, motor control indicators, landing performance, and upper limb functional stability in adolescent female volleyball players. Therefore, assessment of core muscle endurance and neuromuscular deficit screening may help identify functional limitations in athletes and support the development of targeted training programs aimed at improving motor control and reducing injury risk factors.