title: Scapular kinematics during supraspinatus rehabilitation exercise: a comparison of full-can versus empty-can techniques.
abstract: BACKGROUND
  Supraspinatus strengthening is an important component of shoulder rehabilitation. Previous work has determined that the full-can and empty-can exercises elicit the greatest amount of supraspinatus activity. However, scapular kinematics has not been considered when prescribing supraspinatus exercises.
  
  
  OBJECTIVE
  Scapular downward rotation, internal rotation, and anterior tipping during the empty-can exercise are increased when compared with the full-can exercise.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Twenty participants performed full-can and empty-can exercises while an electromagnetic tracking system was used to collect three-dimensional scapular kinematic data. Scapular angles at 30 degrees, 60 degrees, and 90 degrees of the ascending and descending phases of humeral elevation were compared using 2-way repeated measures analysis of variance.
  
  
  RESULTS
  There was more scapular anterior tipping and internal rotation during the empty-can exercise at all sampled humeral elevation angles except at 30 degrees of the descending phase for anterior/posterior tipping (P < .05).
  
  
  CONCLUSIONS
  Scapular anterior tipping and internal rotation are increased during the empty-can exercise, whereas scapular upward rotation was not different between exercises.
  
  
  CONCLUSIONS
  Increased scapular internal rotation and anterior tipping decrease the volume of the supraspinatus outlet during the empty-can exercise. When maintenance of the subacromial space is important, use of the full-can exercise seems most appropriate for selective strengthening of the supraspinatus muscle.
authors.affiliation: Interdisciplinary Program in Human Movement Science, Sports Medicine Research Lab, University of North Carolina at Chapel Hill, CB# 8700, 06F Fetzer Gym, University of North Carolina, Chapel Hill, NC 27599, USA. cthigpen@email.unc.edu
authors.forename: Charles A
authors.initials: CA
authors.lastname: Thigpen
authors.forename: Darin A
authors.initials: DA
authors.lastname: Padua
authors.forename: Nicholas
authors.initials: N
authors.lastname: Morgan
authors.forename: Carly
authors.initials: C
authors.lastname: Kreps
authors.forename: Spero G
authors.initials: SG
authors.lastname: Karas
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular; D012399:Rotation; D012540:Scapula / Q000502:physiology*; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000502:physiology*