Impact of physical activity on the association of overweight and obesity with cardiovascular disease: The Rotterdam Study

Background Being overweight or obese is associated with an increased risk of cardiovascular disease (CVD). Physical activity might reduce the risk associated with overweight and obesity. We examined the association between overweight and obesity and CVD risk as a function of physical activity levels in a middle-aged and elderly population. Design The study was a prospective cohort study. Methods The study included 5344 participants aged 55 years or older from the population-based Rotterdam Study. Participants were classified as having high or low physical activity based on the median of the population. Normal weight (18.5-24.9kg/m(2)), overweight (25.0-29.9kg/m(2)) and obese participants (30kg/m(2)) were categorized as having high or low physical activity to form six categories. We assessed the association of the six categories with CVD risk using Cox proportional hazard models adjusted for confounders. High physical activity and normal weight was used as the reference group. Results During 15 years of follow-up (median 10.3 years, interquartile range 8.2-11.7 years), 866 (16.2%) participants experienced a CVD event. Overweight and obese participants with low physical activity had a higher CVD risk than normal weight participants with high physical activity. The HRs and 95% confidence intervals (CIs) were 1.33 (1.07-1.66) and 1.35 (1.04-1.75), respectively. Overweight and obese participants with high physical activity did not show a higher CVD risk (HRs (95%CIs) 1.03 (0.82-1.29) and 1.12 (0.83-1.52), respectively). Conclusions Our findings suggest that the beneficial impact of physical activity on CVD might outweigh the negative impact of body mass index among middle-aged and elderly people. This emphasizes the importance of physical activity for everyone across all body mass index strata, while highlighting the risk associated with inactivity even among normal weight people.