Physical activity, metabolic syndrome, and coronary risk: the EPIC-Norfolk prospective population study.

Objective: We investigated the association between physical activity, metabolic syndrome (MS), and the risk of future coronary heart disease (CHD) and mortality due to CHD in middle-aged men and women.

Design: Prospective cohort study.

Subjects: A total of 10,134 men and women aged 45-79 years at baseline, were selected from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk cohort. Cardiovascular risk factors and physical activity levels were recorded at baseline. Rates of CHD and CHD mortality were recorded during a follow-up of 10.9 years.

Results: The prevalence of MS was 37.6% in men and 30.2% in women. Hazard ratios (HRs) for future CHD were 1.95 (95% CI 1.65-2.31) for men with MS and 3.17 (95% CI 2.53-3, 97) for women with MS, compared to those without MS. HRs adjusted for age and smoking were 1.52 (95% CI 1.29-1.81) for men and 1.76 (95% CI 1.39-2.23) for women. Additional adjustment for physical activity did not attenuate these risk estimates further [HRs 1.51 (95% CI 1.27-1.79) and 1.74 (95% CI 1.38-2.21), respectively]. CHD risk associated with MS was substantially lower among participants who were physically active. There was no longer a significant difference in CHD event rate between men with MS who were active and men without MS who were inactive (11.5% vs. 12.8%). For women, similar associations were observed (5.3% vs. 5.6%). We found evidence for significant effect modification (p for interaction = 0.006) such that physical activity affected the association between MS and CHD risk.

Conclusion: Middle-aged men and women with MS have an increased risk for future CHD. This CHD risk associated with MS is substantially lower among those who are physically active. Participants with MS who were physically active had a lower CHD risk than people without MS who were physically inactive.