The Effect of Lower Extremity Muscle Fatigue on Dynamic Postural Control Analyzed by Electromyography

Abstract

Purpose: Postural control preserves organs and body parts in a proper biomechanical stance\rwhich exists in two forms: static and dynamic. Fatigue is one of the factors that affects postural\rcontrol. This study aimed to compare the electromyography (EMG) activity of the lower\rextremity muscles before and after fatigue.\rMethods: This study was descriptive correlational and based on the research type a field study.\rStudy sample comprised 20 male students majored in physical education; they were purposefully\rselected by non-accidental all-accounted method. Surface EMG activities of lower extremity\rmuscles before and after fatigue were evaluated by electromyogram. To create fatigue in lower\rextremity muscles, we used fatigue protocol by the Biodex system. Data analysis was carried out by\rusing SPSS 21. The paired t test was used for statistical analysis with a significance level of P<0.05.\rResults: The paired t test results indicated that the activity level of the rectus femoris, hamstrings,\rtibialis anterior, and gastrocnemius muscles significantly changed before and after fatigue. The\rstudy results also supported that lower extremity muscle fatigue had a negative effect on the\ractivity of the muscles around the knee joint. Furthermore, there was a significant relationship\rbetween the postural control and the activity level of rectus femoris and tibialis anterior muscles\ron pretest. However, there were no significant relationships between postural control and activity\rlevel of lateral hamstrings and gastrocnemius muscles on pretest and posttest, nor the activity\rlevel of rectus femoris and tibialis anterior posttest.\rConclusion: Muscle fatigue increases joints vulnerability. These results can be used in designing\rathlete’s rehabilitation programs and trainings to prevent injuries or changes in biomechanical\rparameters of walking.