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

To examine whether the survival benefit of exercise is modified by obesity.

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).

A total of 3298 participants (mean age 69 years, 52% Hispanic, 63% women) were followed over a mean of 11.8 years 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 than 30.

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.