The effect of physical activity (PA) on the risk of developing knee osteoarthritis (OA) is unclear. Our aim was to examine the relationship between recreational PA and incident knee OA outcomes using comparable PA and OA definitions.
Data were acquired from six global, community-based cohorts of participants with/without knee OA. Eligible participants had no evidence of knee OA and rheumatoid arthritis (RA) at baseline. Participants were followed for 5-12 years for incident outcomes including: i) radiographic knee OA (ROA) (Kellgren Lawrence (KL) ≥2), ii) painful radiographic knee OA (PROA) (ROA with knee pain) and iii) OA-related knee pain. Self-reported recreational PA included sport and walking/cycling activities was quantified at baseline as metabolic equivalents of tasks (METS) in days per week (days/wk). Risk ratios (RR) were calculated and pooled using Individual Participant Data (IPD) meta-analysis. Secondary analysis assessed the association between PA, defined as time (hrs/wk) spent in recreational PA and incident knee OA outcomes.
Based on a total of N=5065 participants, pooled risk ratio estimates for MET days/wk and PROA (1.02, 95% CI 0.93, 1.12), ROA (1.00, 95% CI 0.94, 1.07) and OA-related knee pain (1.00, 95% CI 0.96, 1.04) were non-significant, respectively. Similarly, analysis of hours per week spent in PA also showed no significant associations for all outcomes.
Our findings suggest that whole-body, physiological energy expenditure during recreational activities and time spent in physical activity were not associated with incident knee OA outcomes.