Fitness, Fatness, and Mortality: The FIT (Henry Ford Exercise Testing) Project

Abstract

Background The combined influence of fitness and fatness on mortality risk in diverse populations has not been adequately explored. Our aim was to assess the relative impact of exercise capacity and body mass index (BMI) on all-cause mortality.Methods We included 29,257 men and women (mean age 53 years; 27% African American) from The Henry Ford Exercise Testing (FIT) Project without cardiovascular disease and diabetes mellitus at baseline. All patients completed a symptom-limited maximal treadmill stress test between 1991 and 2009. Patients were grouped for analysis by exercise capacity (≥10 metabolic equivalents of task [METs] and <10 METs) and obesity status (≥30 kg/m(2) and <30 kg/m(2)), forming 4 subgroups. Independent and joint associations of BMI and exercise capacity with all-cause mortality were assessed using Cox proportional hazard models.Results During a mean follow-up of 10.8 years, 1898 patients (6.5%) died. We observed a strong inverse association between exercise capacity (per 1 MET unit) and all-cause mortality (hazard ratio [95% confidence interval], 0.86 [0.85-0.88]). Body mass index (per 1 BMI unit) was inversely related to mortality (hazard ratio [95% confidence interval], 0.98 [0.97-0.99]). In joint analysis, the highest mortality risk was in the <10 METs/<30 kg/m(2) subgroup.Conclusions Reduced exercise capacity was a strong independent risk factor for all-cause mortality in this racially diverse population. Given the comparatively limited impact of BMI, more emphasis should be placed on measuring exercise capacity and developing strategies for its improvement in cardiovascular disease prevention programs.