title: Weakening of synergist muscle coupling during reaching movement in stroke patients.
abstract: BACKGROUND
  After hemiparetic stroke, coordination of the shoulder flexor and elbow extensor muscles during a reaching movement is impaired and contributes to poor performance.
  
  
  OBJECTIVE
  The aim was to determine whether functional coupling between electromyographic signals of synergist muscles during reaching was weakened in stroke patients who had poor motor coordination.
  
  
  METHODS
  Surface electromyography (EMG) from the anterior deltoid, triceps brachii, biceps brachii, pectoralis major, supraspinatus, and latissimus dorsi of the affected upper limb in 11 stroke patients (mean Fugl-Meyer upper extremity score 27 ± 8) and in the dominant arm of 8 healthy controls were measured.
  
  
  RESULTS
  Coherence between the EMG of the anterior deltoid and triceps brachii, 2 synergists for reaching, was lower in patients compared with controls, in the 0- to 11-Hz range. Detailed segmented frequency-range analysis indicated significant differences in the coherence between groups in 0- to 3.9-Hz and 4- to 7.9-Hz ranges.
  
  
  CONCLUSIONS
  This weakened functional coupling may contribute to poor reaching performance and could be a consequence of a loss of common drive at the frequency bands as a result of interruption of information flow in the corticospinal pathway.
authors.affiliation: Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kisiel-Sajewicz
authors.forename: Yin
authors.initials: Y
authors.lastname: Fang
authors.forename: Ken
authors.initials: K
authors.lastname: Hrovat
authors.forename: Guang H
authors.initials: GH
authors.lastname: Yue
authors.forename: Vlodek
authors.initials: V
authors.lastname: Siemionow
authors.forename: Chang-Kai
authors.initials: CK
authors.lastname: Sun
authors.forename: Anna
authors.initials: A
authors.lastname: Jaskólska
authors.forename: Artur
authors.initials: A
authors.lastname: Jaskólski
authors.forename: Vinod
authors.initials: V
authors.lastname: Sahgal
authors.forename: Janis J
authors.initials: JJ
authors.lastname: Daly
mesh_terms: D000368:Aged; D001132:Arm / Q000294:innervation / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D010291:Paresis / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D020521:Stroke / Q000150:complications / Q000503:physiopathology*