Physical exercise, body mass index and risk of chronic arm pain: longitudinal data on an adult population in Norway.

AIM: The aim of this study was to prospectively investigate the association between leisure time physical exercise, body mass index (BMI) and risk of chronic arm pain.
METHODS: The study population comprises 14,041 women and 13,674 men in the Norwegian HUNT Study without musculoskeletal pain or physical impairment at baseline in 1984-86. Chronic arm pain was assessed at follow-up in 1995-97. A generalized linear model was used to calculate adjusted relative risks (RRs).
RESULTS: At follow-up, 2205 women and 1458 men reported chronic arm pain. Level of physical exercise was inversely associated with risk of chronic arm pain (P-trend, ≤0.03 for both sexes). Compared with inactive persons, women and men who exercised ≥ 2 h/week had adjusted RRs of 0.84 [95% confidence interval (CI), 0.73-0.96] and 0.74 (95% CI, 0.63-0.87), respectively. BMI was positively associated with risk of chronic arm pain (P-trend, ≤0.002 for both sexes). Compared with normal-weight persons, women and men classified as obese (BMI ≥ 30 kg/m2) had adjusted RRs of 1.26 (95% CI, 1.11-1.44) and 1.29 (95% CI, 1.07-1.57), respectively. Combined analysis showed that obese women and men who exercised  ≥ 1 h/week had a RR of 1.20 (95% CI 0.97-1.48) compared with normal-weight women and men with a similar activity level, whereas the RR was 1.41 (95% CI 1.21-1.65) for obese women and men who were physically inactive.
CONCLUSION: Regular physical exercise reduces risk of chronic arm pain while high BMI increases the risk. Exercise can to some extent compensate for the adverse effect of obesity on risk of chronic arm pain.