Weakening of functional corticomuscular coupling during muscle fatigue

Brain Res. 2009 Jan 23;1250:101-12. doi: 10.1016/j.brainres.2008.10.074. Epub 2008 Nov 11.


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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Arm / physiology
  • Beta Rhythm
  • Brain / physiology*
  • Electroencephalography
  • Electromyography
  • Female
  • Humans
  • Isometric Contraction / physiology
  • Male
  • Middle Aged
  • Muscle Fatigue / physiology*
  • Muscle, Skeletal / physiology*