Exercise Fatigue Related Electromyographic Coherence Analysis between Antagonistic Elbow Muscles

Objective: The aim of this study was to examine coherence between antagonistic elbow muscles and thus to explore the characteristics of common neural inputs to co-contracting antagonistic elbow muscles during sustained isometric fatiguing contraction.Method: Ten healthy male subjects participated in this study.With elbow flexion muscle at 50% maximum voluntary contraction(MVC) to induce muscle fatigue,surface electromyographic signals(sEMG) was collected from biceps brachii(BB) and triceps brachii(TB).sEMG was divided into two segments and coherence analysis was conducted between BB and TB electromyographic signals in both segments.Result: A significant decrease in EMG-EMG coherence in the beta and gamma frequency bands was observed in the second half of the fatiguing contraction compared to the first half of the fatiguing contraction.No significant difference was observed in the tremor band coherence between the first and the second half of the fatiguing contraction.Conclusion: During the sustained isometric fatiguing contraction following the target force level at 50% MVC,common neural input across BB and TB muscles decreased in the second half of the fatigue contraction compared to the first half of the fatiguing contraction,which might be related to asynchronism of failure to activate spinal motoneurons and reduction in motoneuron excitability in antagonistic elbow muscles following muscle fatigue and different motor unit recruitment patterns was adopted to coordinate force generation which may help to maintain the target force level more efficiently as the muscle fatigues.