Background Physical exercise has been shown to have beneficial effects in patients with osteoarthritis (OA)¹. However, it is unclear which mediating mechanisms of action underlie the relationship between physical exercise and its effect on pain and activity limitations associated with OA. Although the effect of physical exercise on many possible mediators has been measured extensively, the associations between these mediators and pain and activity limitations gained little interest.

Objectives To give an overview of physiological/biological factors measured prior to and post-exercise in patients with OA, discuss their possible role as mediating mechanisms involved in physical exercise and extract the data if possible.

Methods Articles evaluating the effect of a physical exercise intervention in patients with OA were identified by a systematic search conducted in the Pubmed (1966 – August 2011) and Embase (1974 – August 2011) databases. Inclusion criteria for eligible studies were: number of human participants ≥10, OA was diagnosed according to validated criteria, a physical exercise intervention was applied, and study involved baseline and follow-up measurements.

Used key terms were: physical therapy modalities, physical exertion, exercise, sports, clinical trial, random*, epidemiologic research design, osteoarthritis (Pubmed) and physical activity, capacity and performance, physiotherapy, kinesiotherapy, sport, osteoarthritis, types of study (Embase). Titles and abstracts were screened independently by two reviewers. Data extraction was done by two reviewers. Descriptive statistics were applied to report the results.

Results The search yielded 1,291 titles/abstracts of which 77 articles were included in the review. Increased muscle strength following physical exercise was reported in 48 articles. Increased pro- and anti-inflammatory cytokines, decreased cartilage matrix related serum biomarkers, increased intraarticular oxygen, increased muscle tissue related proteins and/or improved kinematics were reported in 20 articles. One article provided additional analyses of the relationship between biomarker levels and pain and functional outcome measures, reporting a weak significant association between change in Western Ontario and McMaster Universities Osteoarthritis Index pain and change in antigenic keratan sulfate. Knee OA was investigated in 63 articles; remaining articles investigated hip and knee (8), hip (2), hand (2) or ankle (1) OA. One article provided no information about the investigated joint.

Conclusions The findings of this review indicated several possible mechanisms that may explain the beneficial effects of physical exercise in patients with OA. Evidence for the mediating mechanisms of physical exercise affecting pain and activity limitations is scarce.

1. Fransen M, McConnell S. Exercise for osteoarthritis of the knee. Cochrane Database Syst Rev. 2008(4):CD004376.

Disclosure of Interest None Declared