Katzmarzyk, Peter T. FACSM¹; Church, Timothy S.²; Janssen, Ian¹; Ross, Robert¹; Blair, Steven N. FACSM²

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The relationships among obesity, the metabolic syndrome, cardiorespiratory fitness (CRF), and risk of cardiovascular disease (CVD) mortality are complex and not well understood. PURPOSE: To determine the impact of CRF on the CVD mortality risk associated with the metabolic syndrome in normal weight, overweight and obese men. METHODS: The sample included 19,173 adult male participants from the Aerobics Center Longitudinal Study in Dallas, TX. All participants underwent a clinical examination including a maximal treadmill test to assess CRF. The metabolic syndrome was defined according to the Adult Treatment Panel III guidelines as having at least three of the following risk factors: waist circumference >102 cm, triglycerides ≥1.69 mmol/L, HDL-cholesterol <1.04 mmol/L, glucose ≥6.1 mmol/L, and high blood pressure (≥130 mmHg systolic or ≥85 mmHg diastolic). A total of 160 CVD deaths occurred over an average 10.2 years of follow-up. RESULTS: After adjustment for age, year of examination, smoking status, alcohol consumption, and parental CVD, the relative risks [95% confidence interval] of CVD mortality were 2.29 [1.02–5.14] in normal weight men, 1.92 [1.17–3.15] in overweight men, and 3.11 [1.87–5.18] in obese men with the metabolic syndrome by comparison to normal weight men who did not have the metabolic syndrome. After further adjustment for CRF, the relative risk estimate in each BMI category were greatly attenuated and were no longer statistically significant. CONCLUSION: Cardiorespiratory fitness offers significant protection from CVD mortality associated with the metabolic syndrome and is independent of body weight status. Supported by grants AG06945 from the National Institute on Aging and T4945 from the Heart and Stroke Foundation of Ontario.