Excess Body Mass and Leisure Time Physical Activity in the Incidence and Persistence of Chronic Pain

Objective. To estimate the effects of excess body mass and leisure time physical activity on the incidence and persistence of chronic pain. Design. A prospective cohort study. Methods. As a part of the Finnish Helsinki Health Study, we included three cohorts of employees of the City of Helsinki (18,562 observations) and defined incident chronic pain as having pain in any part of the body for more than three months at follow-up in participants without chronic pain at baseline (N = 13,029 observations). Persistent chronic pain was defined as having pain for more than three months at both baseline and follow-up (N = 5,533 observations). Results. Overweight (adjusted odds ratio [OR] = 1.18, 95% confidence interval [CI] = 1.06-1.31) and obesity (OR = 1.65, 95% CI = 1.45-1.88) increased the incidence of chronic pain. Moreover, overweight (OR = 1.16, 95% CI = 1.02-1.32) and obesity (OR = 1.48, 95% CI = 1.26-1.74) increased the risk of persistent chronic pain. Vigorous leisure time physical activity reduced the incidence of chronic pain (OR = 0.85, 95% CI = 0.75-0.96). Physical activity did not influence the risk of persistent chronic pain. Furthermore, overweight/obesity modified the effect of leisure time physical activity on incident chronic pain. Inactive overweight or obese participants were at the highest risk of chronic pain (OR = 1.71, 95% CI = 1.40-2.09), while the OR dropped to 1.44 (95% CI = 1.19-1.75) in moderately active overweight or obese participants and to 1.20 (95% CI = 0.97-1.47) in highly active overweight or obese participants. Conclusions. Obesity not only increases the risk of developing chronic pain, but also increases the risk of persistent pain, while leisure time physical activity reduces the risk of developing chronic pain.