title: Weakening of functional corticomuscular coupling during muscle fatigue.
abstract: 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.
  
  
  CONCLUSIONS
  Weakening of corticomuscular coupling may be a major neural mechanism contributing to muscle fatigue and associated performance impairment.
authors.affiliation: Department of Biomedical Engineering, the Lerner Research Institute, The Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.forename: Yin
authors.initials: Y
authors.lastname: Fang
authors.forename: Chang-Kai
authors.initials: CK
authors.lastname: Sun
authors.forename: Vlodek
authors.initials: V
authors.lastname: Siemionow
authors.forename: Vinoth K
authors.initials: VK
authors.lastname: Ranganathan
authors.forename: Dilara
authors.initials: D
authors.lastname: Khoshknabi
authors.forename: Mellar P
authors.initials: MP
authors.lastname: Davis
authors.forename: Declan
authors.initials: D
authors.lastname: Walsh
authors.forename: Vinod
authors.initials: V
authors.lastname: Sahgal
authors.forename: Guang H
authors.initials: GH
authors.lastname: Yue
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology; D001611:Beta Rhythm; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*