title: A randomized controlled trial of eccentric vs. concentric graded exercise in chronic tennis elbow (lateral elbow tendinopathy).
abstract: OBJECTIVE
  To analyse treatment effects of eccentric vs. concentric graded exercise in chronic tennis elbow.
  
  
  METHODS
  Randomized controlled trial.
  
  
  METHODS
  Primary care in Uppsala County, Sweden.
  
  
  METHODS
  A total of 120 subjects with tennis elbow lasting more than three months were recruited from primary care and by advertisement.
  
  
  METHODS
  Eccentric (n = 60) or concentric exercise (n = 60), by lowering or lifting a weight, at home daily, for three months with gradually increasing load.
  
  
  METHODS
  Pain during muscle contraction and muscle elongation, as well as strength, was assessed at baseline and after one, two, three, six, and 12 months. Function and quality of life was assessed at baseline and after three, six and 12 months.
  
  
  RESULTS
  The eccentric exercise group had faster regression of pain, with an average of 10% higher responder rate at all levels of pain reduction, both during muscle contraction and elongation, (p < 0.0001 and p = 0.006, respectively). Significant differences were found in Cox's analysis from two months onwards (HR 0.78, 95% confidence interval (CI) 0.63-0.96, p < 0.02). This represents an absolute pain reduction of 10% in the eccentric vs. the concentric group and a number-needed-to-treat of 10. The eccentric group also had a greater increase of muscle strength than the concentric (p < 0.02). The differences persisted throughout the follow-up period. There were no significant differences between the groups regarding function or quality of life measures.
  
  
  CONCLUSIONS
  Eccentric graded exercise reduced pain and increased muscle strength in chronic tennis elbow more effectively than concentric graded exercise.
authors.affiliation: Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden magnus.peterson@pubcare.uu.se.
authors.forename: Magnus
authors.initials: M
authors.lastname: Peterson
authors.affiliation: Department of Surgical Sciences/Anesthesiology and Intensive Care Medicine, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: Stephen
authors.initials: S
authors.lastname: Butler
authors.affiliation: Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Margaretha
authors.initials: M
authors.lastname: Eriksson
authors.affiliation: Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Kurt
authors.initials: K
authors.lastname: Svärdsudd
mesh_terms: D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010043:Outcome and Process Assessment, Health Care; D059408:Pain Management / Q000379:methods*; D013548:Sweden; D013716:Tennis Elbow / Q000628:therapy*
keywords: Concentric; concentric exercise; eccentric; eccentric exercise; pain; randomized controlled trial; tendinopathy; tennis elbow