title: Investigation of supraspinatus muscle architecture following concentric and eccentric training.
abstract: OBJECTIVE
  To investigate the effects of concentric or eccentric abduction strength training on supraspinatus fiber bundle architecture and strength.
  
  
  METHODS
  A pre-post single-subject design.
  
  
  METHODS
  Thirteen participants were randomized to concentric (n=6) or eccentric (n=7) training groups. Participants completed an eight week shoulder abduction training program in the scapular plane using an isokinetic dynamometer. Resistance training, requiring maximal effort on contraction, consisted of 4 sets of 8 reps at 60°/s in weeks 1-4, and 6 sets of 6 reps at 60°/s in weeks 5-8 with a frequency of 3×/week. Primary outcome measures included fiber bundle length, pennation angle, and muscle thickness of supraspinatus and these were quantified using ultrasound. Secondary outcome measures included isometric, eccentric and concentric abduction strength and these were evaluated using the isokinetic dynamometer.
  
  
  RESULTS
  Mean fiber bundle length in the relaxed (p=0.033) and contracted (p=0.036) states significantly decreased with concentric training but remained unchanged with eccentric training. A significant increase in pennation angle, muscle thickness, and peak torque were found with training but no significant differences were detected between concentric and eccentric groups.
  
  
  CONCLUSIONS
  Training mode has a significant impact on fiber bundle length changes of the supraspinatus. Eccentric training of shoulder abduction leads to similar strength gains as concentric, but it may also have the added advantages of maintaining fiber bundle lengths and promoting tendon healing. Study is needed to confirm fiber bundle changes in a clinical population which would further support the use of eccentric abduction strength training in rehabilitation settings.
authors: School of Physical Therapy, University of Saskatchewan, Canada. Electronic address: soo.kim@usask.ca.
authors: Soo Y
authors: SY
authors: Kim
authors: Department of Physiology, University of Saskatchewan, Canada(1).
authors: Jong Bum
authors: JB
authors: Ko
authors: College of Kinesiology, University of Saskatchewan, Canada.
authors: Jonathan P
authors: JP
authors: Farthing
authors: School of Physical Therapy, University of Saskatchewan, Canada.
authors: Scotty J
authors: SJ
authors: Butcher
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D053580:Muscle Strength; D009929:Organ Size; D055070:Resistance Training / Q000379:methods*; D017006:Rotator Cuff / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D019415:Torque; D014463:Ultrasonography; D055815:Young Adult
keywords: Exercise; Fiber bundle; Rehabilitation; Rotator cuff; Shoulder; Torque