title: Shoulder Coordination During Full-Can and Empty-Can Rehabilitation Exercises.
abstract: BACKGROUND
  Supraspinatus tear is a common rotator cuff injury. During rehabilitation, debate persists regarding the most appropriate exercises. Whereas shoulder coordination is part of normal arm function, it has been infrequently considered in the context of exercise selection.
  
  
  OBJECTIVE
  To assess shoulder-motion coordination during 2 common supraspinatus rehabilitation exercises and to characterize load and motion-direction influences on shoulder coordination.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Motion-analysis laboratory. Patient or Other Participants :  Fifteen asymptomatic right-hand-dominant men (age = 26 ± 4 years, height = 1.77 ± 0.06 m, mass = 74.3 ± 7.7 kg).
  
  
  METHODS
  Full-can and empty-can exercises with and without a 2.27-kg load.
  
  
  METHODS
  We recorded motion with an optoelectronic system. Scapulohumeral rhythm and complete shoulder joint kinematics were calculated to quantify shoulder coordination. The effects of exercise type, load, motion direction, and humerothoracic-elevation angle on the scapulohumeral rhythm and shoulder-joint angles were assessed.
  
  
  RESULTS
  We observed multivariate interactions between exercise type and humerothoracic elevation and between load and humerothoracic elevation. Scapulohumeral rhythm increased by a mean ratio of 0.44 ± 0.22 during the full-can exercise, whereas the addition of load increased mean glenohumeral elevation by 4° ± 1°.
  
  
  CONCLUSIONS
  The full-can exercise increased the glenohumeral contribution, as hypothesized, and showed normal shoulder coordination. During the empty-can exercise, the increased scapulothoracic contribution was associated with a compensatory pattern that limits the glenohumeral contribution. Using loads during shoulder rehabilitation seems justified because the scapulohumeral rhythm is similar to that of unloaded arm elevation. Finally, motion direction showed a limited effect during the exercises in healthy individuals.
authors.affiliation: Department of Kinesiology, Montreal University, QC, Canada;
authors.forename: Xavier
authors.initials: X
authors.lastname: Robert-Lachaine
authors.affiliation: Department of Kinesiology, Montreal University, QC, Canada;
authors.forename: Paul
authors.initials: P
authors.lastname: Allard
authors.affiliation: Centre Hospitalier Universitaire de Montréal (CHUM), Notre-Dame Hospital, Montreal, QC, Canada.
authors.forename: Veronique
authors.initials: V
authors.lastname: Gobout
authors.affiliation: Department of Kinesiology, Montreal University, QC, Canada;
authors.forename: Mickael
authors.initials: M
authors.lastname: Begon
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005081:Exercise Therapy / Q000379:methods*; D064368:Healthy Volunteers; D006801:Humans; D007592:Joint Diseases / Q000503:physiopathology; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology; D000070636:Rotator Cuff Injuries; D012421:Rupture / Q000534:rehabilitation; D012540:Scapula / Q000503:physiopathology; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000503:physiopathology
keywords: kinematics; scapulohumeral rhythm; shoulder joint; supraspinatus muscle