title: The influence of induced shoulder muscle pain on rotator cuff and scapulothoracic muscle activity during elevation of the arm.
abstract: BACKGROUND
  Altered recruitment of rotator cuff and scapulothoracic muscles has been identified in patients with subacromial impingement syndrome. To date, however, the cause-consequence relationship between pain and altered muscle recruitment has not been fully unraveled.
  
  
  METHODS
  The effect of experimental shoulder pain induced by injection of hypertonic saline in the supraspinatus on the activity of the supraspinatus, infraspinatus, subscapularis, trapezius, and serratus anterior activity was investigated during the performance of an elevation task by use of muscle functional magnetic resonance imaging in 25 healthy individuals. Measurements were taken at 4 levels (C6-C7, T2-T3, T3-T4, and T6-T7) at rest and after the elevation task performed without and with experimental shoulder pain.
  
  
  RESULTS
  During arm elevation, experimentally induced pain caused a significant activity reduction, expressed as reduction in T2 shift of the IS (P = .029). No significant changes in T2 shift values were found for the other rotator cuff muscles or the scapulothoracic muscles.
  
  
  CONCLUSIONS
  This study demonstrates that acute experimental shoulder pain has an inhibitory effect on the activity of the IS during arm elevation. Acute experimental shoulder pain did not seem to influence the scapulothoracic muscle activity significantly. The findings suggest that rotator cuff muscle function (infraspinatus) should be a consideration in the early management of patients with shoulder pain.
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium. Electronic address: Birgit.Castelein@ugent.be.
authors.forename: Birgit
authors.initials: B
authors.lastname: Castelein
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Ann
authors.initials: A
authors.lastname: Cools
authors.affiliation: Department of Physical Medicine and Orthopedic Surgery, University Hospital, Ghent, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Parlevliet
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cagnie
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009068:Movement / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D063806:Myalgia / Q000503:physiopathology*; D010147:Pain Measurement; D017006:Rotator Cuff / Q000000981:diagnostic imaging*; D020069:Shoulder Pain / Q000503:physiopathology*; D034941:Upper Extremity / Q000502:physiology
keywords: Experimental pain; exercise; muscle functional magnetic resonance imaging; muscles; rotator cuff; scapula; shoulder pain