title: Association of exercise therapy and reduction of pain sensitivity in patients with knee osteoarthritis: a randomized controlled trial.
abstract: OBJECTIVE
  Exercise has beneficial effects on pain in knee osteoarthritis (OA), yet the underlying mechanisms are unclear. The purpose of this study was to investigate the effects of exercise on pressure-pain sensitivity in patients with knee OA.
  
  
  METHODS
  In a randomized controlled trial, participants were assigned to 12 weeks of supervised exercise therapy (ET; 36 sessions) or a no attention control group (CG). Pressure-pain sensitivity was assessed by cuff pressure algometry on the calf of the most symptomatic leg. The coprimary outcomes were pressure-pain thresholds (PPTs) and cumulated visual analog scale pain scores during constant pressure for 6 minutes at 125% of the PPT as a measure of temporal summation (TS) of pressure-pain. Secondary outcomes included self-reported pain using the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Analyses were based on the "per-protocol" population (participants following the protocol).
  
  
  RESULTS
  Sixty participants were randomized (31 in ET group, 29 in CG), and the per-protocol population included 48 participants (25 in ET group, 23 in CG). At followup, mean group differences in the change from baseline were 3.1 kPa (95% confidence interval [95% CI] 0.2, 6.0; P = 0.038) for the PPT, 2,608 mm × seconds (95% CI 458, 4,758; P = 0.019) for TS, and 6.8 points (95% CI 1.2, 12.4; P = 0.018) for KOOS pain, all in favor of ET.
  
  
  CONCLUSIONS
  Pressure-pain sensitivity, TS, and self-reported pain are reduced among patients completing a 12-week supervised exercise program compared to a no attention CG. These results demonstrate beneficial effects of exercise on basic pain mechanisms and further exploration may provide a basis for optimized treatment.
authors.affiliation: Copenhagen University Hospitals Bispebjerg and Frederiksberg, Copenhagen, Denmark.
authors.forename: Marius
authors.initials: M
authors.lastname: Henriksen
authors.forename: Louise
authors.initials: L
authors.lastname: Klokker
authors.forename: Thomas
authors.initials: T
authors.lastname: Graven-Nielsen
authors.forename: Cecilie
authors.initials: C
authors.lastname: Bartholdy
authors.forename: Tanja
authors.initials: T
authors.lastname: Schjødt Jørgensen
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bandak
authors.forename: Bente
authors.initials: B
authors.lastname: Danneskiold-Samsøe
authors.forename: Robin
authors.initials: R
authors.lastname: Christensen
authors.forename: Henning
authors.initials: H
authors.lastname: Bliddal
mesh_terms: D000328:Adult; D000368:Aged; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000503:physiopathology / Q000534:rehabilitation*; D010146:Pain / Q000209:etiology / Q000503:physiopathology / Q000534:rehabilitation*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D011312:Pressure; D016037:Single-Blind Method; D011795:Surveys and Questionnaires; D016896:Treatment Outcome