Supplementary balance training fails to protect against fatigue-induced sway in professional volleyball players.

BACKGROUND

Professional volleyball demands high-level neuromuscular control, yet frequent physical exhaustion during competition can compromise postural stability. While balance training is often utilized in athletic training programs, its specific efficacy in mitigating fatigue-induced deficits among elite athletes remains under-investigated. The aim of this study was to determine whether 12 weeks of supplementary balance training, integrated into a routine athletic schedule, improves fatigue-induced postural sway in professional female volleyball players.

METHODS

Twenty-three professional female volleyball players from two professional teams participated in this non-randomized, controlled study. One team implemented supplementary balance training in addition to routine practice, whereas the other team continued their standard seasonal program. Eleven players were in the training team, and twelve were in the control team. Postural sway was assessed using the Overall Stability Index (OSI), Anterior-Posterior Stability Index (APSI), and Medial-Lateral Stability Index (MLSI) with the Biodex Balance Systems SD device. Measurements were taken at baseline and multiple time points (0, 10, 20, 30 min) after Bruce protocol, both before and after the 12-week intervention. Data were analyzed using a robust rank-based, non-parametric method and by estimating relative treatment effects (RTEs) with 95% confidence intervals (CIs).

RESULTS

Post-intervention analysis revealed no significant group-by-time interaction for OSI (p = 0.303), APSI (p = 0.397), or MLSI (p = 0.113). These results indicate that the trajectory of balance loss and recovery following high-intensity exercise was statistically similar for both groups. While a significant main effect of time was observed (p < 0.001), confirming that high-intensity exercise impaired stability, the supplementary balance training did not provide a statistically superior resistance to fatigue compared to routine training alone. Consistent with the non-significant group-by-time interaction tests (p > 0.05 for all stability indices), the 95% CIs of the RTEs overlapped substantially at all post-exercise time points; however, inferential conclusions are based on the interaction test results.

CONCLUSIONS

Supplementary balance training did not provide a statistically significant advantage in mitigating fatigue-induced postural instability compared to routine training in this sample.