Leisure-time physical activity and mortality in a multiethnic prospective cohort study: The Northern Manhattan Study

Purpose: To examine whether the survival benefit of exercise is modified by obesity. Methods: In the Northern Manhattan Study, we collected baseline sociodemographics and cardiovascular disease risk factors. The primary exposure was leisure-time physical activity (LTPA) and the outcomes were total, vascular, and nonvascular deaths (non-VaD). LTPA was defined as any versus none and metabolic equivalent score category (total activity weighted by intensity). We used Cox models to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs). Results: A total of 3298 participants (mean age 69 years, 52% Hispanic, 63% women) were followed over a mean of 11.8years with 1589 total deaths (641 vascular, 819 nonvascular). Any activity (adjusted HR: 0.84, 95% CI: 0.75-0.94) was associated with reduced risk of all-cause mortality and non-VaD, but not VaD. We found an interaction (P<.05) of LTPA with body mass index (BMI) less than 30 for all-cause and vascular mortality. Any LTPA was associated with reduced all-cause mortality (adjusted HR: 0.77, 95% CI: 0.68-0.87) and VaD (adjusted HR: 0.79, 95% CI: 0.65-0.97) only among those with BMI less than30. Conclusions: We found no evidence of an independent survival benefit of LTPA among those with BMI more than 30. The health benefits of exercise should be considered in the context of obesity.