Cardiorespiratory fitness attenuates the effects of the metabolic syndrome on all-cause and cardiovascular disease mortality in men.

BACKGROUND The metabolic syndrome is a prevalent condition that carries with it an increased risk of type 2 diabetes mellitus, cardiovascular disease (CVD), and mortality. OBJECTIVE To determine the relationship between cardiorespiratory fitness (CRF) and mortality in healthy men and in those with the metabolic syndrome. METHODS The sample included 19 223 men, aged 20 to 83 years, who received a clinical evaluation between 1979 and 1995 with mortality follow-up through December 31, 1996. There were 15 466 healthy men (80.5%) and 3757 men with the metabolic syndrome (19.5%). RESULTS A total of 480 deaths (161 due to CVD) occurred during 196 298 man-years of follow-up. After adjustment for age, year of examination, smoking status, alcohol consumption, and parental CVD, the relative risks (RRs) (95% confidence interval) of all-cause and CVD mortality were 1.29 (1.05-1.57) and 1.89 (1.36-2.60), respectively, for men with the metabolic syndrome compared with healthy men. After the inclusion of CRF, the associations were not significant. The RRs comparing unfit with fit men for all-cause mortality were 2.18 (1.66-2.87) in healthy men and 2.01 (1.38-2.93) in men with the metabolic syndrome, whereas the RRs for CVD mortality for unfit vs fit men were 3.21 (2.03-5.07) in healthy men and 2.25 (1.27-3.97) in men with the metabolic syndrome. A significant dose-response relationship between CRF and mortality was also observed in men with the metabolic syndrome. CONCLUSION In this sample, CRF provided a strong protective effect against all-cause and CVD mortality in healthy men and men with the metabolic syndrome.