title: Acute resistance exercise and pressure pain sensitivity in knee osteoarthritis: a randomised crossover trial.
abstract: OBJECTIVE
  To determine whether a single bout of resistance exercise produces an analgesic effect in individuals with knee osteoarthritis (OA).
  
  
  METHODS
  Eleven participants with knee OA (65.9 ± 10.4 yrs), and 11 old (61.3 ± 8.2 yrs) and 11 young (25.0 ± 4.9 yrs) healthy adults performed separate bouts of upper and lower body resistance exercise. Baseline and post-exercise pressure pain thresholds were measured at eight sites across the body and pressure pain tolerance was measured at the knee.
  
  
  RESULTS
  Pressure pain thresholds increased following exercise for all three groups, indicating reduced pain sensitivity. For the young and old healthy groups this exercise-induced analgesia (EIA) occurred following upper or lower body resistance exercise. In contrast, only upper body exercise significantly raised pain thresholds in the knee OA group, with variable non-significant effects following lower body exercise. Pressure pain tolerance was unchanged in all groups following either upper or lower body exercise.
  
  
  CONCLUSIONS
  An acute bout of upper or lower body exercise evoked a systemic decrease in pain sensitivity in healthy individuals irrespective of age. The decreased pain sensitivity following resistance exercise can be attributed to changes in pain thresholds, not pain tolerance. While individuals with knee OA experienced EIA, a systemic decrease in pain sensitivity was only evident following upper body exercise.
authors.affiliation: School of Medical Sciences, University of New South Wales, Sydney, Australia. Electronic address: n.burrows@unsw.edu.au.
authors.forename: N J
authors.initials: NJ
authors.lastname: Burrows
authors.affiliation: School of Medical Sciences, University of New South Wales, Sydney, Australia. Electronic address: john.booth@unsw.edu.au.
authors.forename: J
authors.initials: J
authors.lastname: Booth
authors.affiliation: School of Medical Sciences, University of New South Wales, Sydney, Australia; Neuroscience Research Australia, Sydney, Australia. Electronic address: d.sturnieks@neura.edu.au.
authors.forename: D L
authors.initials: DL
authors.lastname: Sturnieks
authors.affiliation: School of Medical Sciences, University of New South Wales, Sydney, Australia; Neuroscience Research Australia, Sydney, Australia. Electronic address: ben.barry@unsw.edu.au.
authors.forename: B K
authors.initials: BK
authors.lastname: Barry
mesh_terms: D000328:Adult; D000368:Aged; D018771:Arthralgia / Q000628:therapy*; D016022:Case-Control Studies; D005081:Exercise Therapy / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000628:therapy*; D059408:Pain Management / Q000379:methods*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D011312:Pressure; D055070:Resistance Training / Q000009:adverse effects*; D055815:Young Adult
keywords: Osteoarthritis; Pain; Resistance exercise