title: Is a positive clinical outcome after exercise therapy for chronic non-specific low back pain contingent upon a corresponding improvement in the targeted aspect(s) of performance? A systematic review.
abstract: BACKGROUND
  The effect size for exercise therapy in the treatment of chronic non-specific low back pain (cLBP) is only modest. This review aims to analyse the specificity of the effect by examining the relationship between the changes in clinical outcome (pain, disability) and the changes in the targeted aspects of physical function (muscle strength, mobility, muscular endurance) after exercise therapy.
  
  
  METHODS
  We searched for exercise therapy trials for cLBP published up to 15 April 2010 in Medline, Embase, Cochrane Library, Cinahl, and PEDro. Two independent reviewers selected studies according to the inclusion criteria.
  
  
  METHODS
  one author extracted the data of the articles.
  
  
  RESULTS
  
  
  
  RESULTS
  16 studies with a total of 1,476 participants met the inclusion criteria. There was little evidence supporting a relationship between the changes in pain or physical function and the changes in performance for the following measures: mobility (no correlation in 9 studies, weak correlation in 1 study), trunk extension strength (7 and 2, respectively), trunk flexion strength (4 and 1, respectively) and back muscle endurance (7 and 0, respectively). Changes in disability showed no correlation with changes in mobility in three studies and a weak correlation in two; for strength, the numbers were four (no correlation) and two (weak correlation), respectively.
  
  
  CONCLUSIONS
  The findings do not support the notion that the treatment effects of exercise therapy in cLBP are directly attributable to changes in the musculoskeletal system. Future research aimed at increasing the effectiveness of exercise therapy in cLBP should explore the coincidental factors influencing symptom improvement.
authors.affiliation: Institute of Human Movement Sciences and Sport, ETH Zürich, Zurich, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Steiger
authors.forename: B
authors.initials: B
authors.lastname: Wirth
authors.forename: E D
authors.initials: ED
authors.lastname: de Bruin
authors.forename: A F
authors.initials: AF
authors.lastname: Mannion
mesh_terms: D004185:Disability Evaluation; D005081:Exercise Therapy; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology / Q000628:therapy*; D053580:Muscle Strength / Q000502:physiology*; D009141:Musculoskeletal System / Q000503:physiopathology; D010807:Physical Endurance / Q000502:physiology*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
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