Comparing the Effects of Lower Extremity Muscle Fatigue on Dynamic Balance of Volleyball Players

Objectives: Lower extremity muscles are important for maintaining dynamic balance and athletic performance. Fatigue of these muscles may affect dynamic balance. It is not clear whether fatigue in a particular muscle group can affect dynamic balance more than fatigue in other groups. This study was conducted to evaluate and compare the effects of fatigue in five muscle groups on the dynamic balance of volleyball players. Methods: Fifteen healthy male volleyball players performed the Star Excursion Balance Test, before and immediately after fatigue of ankle plantar flexor(PF), knee extensor, knee flexor, hip abductor and hip adductor muscles, separately. Composite reach distance and distance in anterior, posteromedial, and posterolateral directions were recorded. Results: Repeated measure ANOVA showed that fatigue of all muscle groups significantly decreased the mean of composite score (p<0.001). Anterior, posteromedial and posterolateral distance scores decreased following fatigue of knee extensors and ankle PFs (p<0.05). Discussion: This study showed that regarding composite reach score, fatigue of ankle, knee and hip muscles decreased dynamic balance in a similar manner. However, evaluating three main directions revealed that knee extensors’ and ankle PFs’ fatigue have more prominent effects on volleyball players’ balance than other muscles.