title: Effects of spinal cord injury level on the activity of shoulder muscles during wheelchair propulsion: an electromyographic study.
abstract: OBJECTIVE
  To determine the influence of spinal cord injury (SCI) level on shoulder muscle function during wheelchair propulsion.
  
  
  METHODS
  Fine-wire electromyographic activity of 11 muscles was recorded during wheelchair propulsion.
  
  
  METHODS
  Biomechanics research laboratory.
  
  
  METHODS
  Convenience sample of 69 men, in 4 groups by SCI level (low paraplegia, n=17; high paraplegia, n=19; C7-8 tetraplegia, n=16; C6 tetraplegia, n=17).
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Timing of muscle activity onset, cessation, and duration, and time of peak intensity for each functional group were compared with 1-way analysis of variance. Median electromyographic intensity was also compared.
  
  
  RESULTS
  Two functional synergies were observed: push (anterior deltoid, pectoralis major, supraspinatus, infraspinatus, serratus anterior, biceps) and recovery (middle and posterior deltoid, supraspinatus, subscapularis, middle trapezius, triceps). Push phase activity began in late recovery and ceased in early to late push. Recovery phase muscles functioned from late push to late recovery. Recruitment patterns for the groups with paraplegia were remarkably similar. For subjects with tetraplegia, pectoralis major activity was significantly prolonged compared with subjects with paraplegia (P<.05). Subscapularis activity shifted from a recovery pattern in subjects with paraplegia to a push pattern in persons with tetraplegia.
  
  
  CONCLUSIONS
  Level of SCI significantly affected the shoulder muscle recruitment patterns during wheelchair propulsion. Differences in rotator cuff and pectoralis major function require specific considerations in rehabilitation program design.
authors.affiliation: Pathokinesiology Laboratory, Rancho Los Amigos National Rehabilitation Center, 7601 Imperial Highway, Building 800, Room 33, Downey, CA 90242, USA.
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Mulroy
authors.forename: Shawn
authors.initials: S
authors.lastname: Farrokhi
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Newsam
authors.forename: Jacquelin
authors.initials: J
authors.lastname: Perry
mesh_terms: D000054:Acceleration; D000293:Adolescent; D000328:Adult; D004576:Electromyography; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D010264:Paraplegia / Q000503:physiopathology; D011782:Quadriplegia / Q000503:physiopathology; D011999:Recruitment, Neurophysiological / Q000502:physiology; D012782:Shoulder / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology* / Q000534:rehabilitation; D014910:Wheelchairs