The effect of functional fatigue on timing of electromyography activity of quadriceps and hamstring muscles during single leg jump-landing task in female athletes

Previous studies have shown that fatigue at the end of athletic events is one of the risk factors for ACL injury, causing changes in neuromuscular activity pattern of the muscles around the knee. But few studies have dealt with the effect of functional fatigue in situations similar to real sport conditions of on neuromuscular factors leading to ACL injury. The aim of this study was to evaluate the effect of functional fatigue on timing of muscles involved in ACL injury during single leg jump-landing task in female athletes.
Material and This study included 15 female volleyball, basketball and handball players. Electromyography activity of the quadriceps and hamstring muscles were recorded before and after single leg jump-landing task. For data analysis we used multivariate analysis of variance with repeated measures at significance level of 95% and alpha less than or equal to 0.05.
According to the results, fatigue can lead to a delay in the onset of vastus lateralis (p=0.002) and semitendinosus muscles activity (p=0.049); while there were no significant differences in the onset of activity of rectus femoris (p=0.143), vastus medialis (p=0.670) and biceps femoris muscles (p=0.226) between before and after fatigue.
The results showed that fatigue can cause delayed onset of activity of semitendinosus and vastus lateralis muscles, leading to changes in neuromuscular patterns of muscles activation in jump-landing task. This may expose ACL to injury. Therefore, we recommend appropriate training programs to increase muscle performance during fatigue.