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Updated: Jun 27, 2026

Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
Weakening of functional corticomuscular coupling during muscle fatigue
Qi Yang1, Yin Fang, Chang-Kai Sun
1Department of Biomedical Engineering, the Lerner Research Institute, The Cleveland Clinic, Cleveland, OH 44195, USA.
Objective:
Recent research has shown dissociation between changes in brain and muscle signals during voluntary muscle fatigue, which may suggest weakening of functional corticomuscular coupling. However, this weakening of brain-muscle coupling has never been directly evaluated. The purpose of this study was to address this issue by quantifying EEG-EMG coherence at times when muscles experienced minimal versus significant fatigue.
Methods:
Nine healthy subjects sustained an isometric elbow flexion at 30% maximal level until exhaustion while their brain (EEG) and muscle (EMG) activities were recorded. The entire duration of the EEG and EMG recordings was divided into the first half (stage 1 with minimal fatigue) and second half (stage 2 with severer fatigue). The EEG-EMG coherence and power spectrum in each stage was computed.
Results:
The power of both EEG and EMG increased significantly while their coherence decreased significantly in stage 2 compared with stage 1 at beta (15-35 Hz) band.
Conclusions:
Despite an elevation of the power for both the EEG and EMG activities with muscle fatigue, the fatigue weakens strength of brain-muscle signal coupling at beta frequency band.
Significance:
Weakening of corticomuscular coupling may be a major neural mechanism contributing to muscle fatigue and associated performance impairment.
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