Physical inactivity, abdominal obesity and risk of coronary heart disease in apparently healthy men and women.

OBJECTIVE

To test the hypothesis that for any given body mass index (BMI) category, active individuals would have a smaller waist circumference than inactive individuals. Our second objective was to examine the respective contribution of waist circumference and physical inactivity on coronary heart disease (CHD) risk.

DESIGN

Prospective, population-based study with an 11.4-year follow-up.

SUBJECTS

A total of 21 729 men and women aged 45-79 years, residing in Norfolk, UK.

METHODS

During follow-up, 2191 CHD events were recorded. Physical activity was evaluated using a validated lifestyle questionnaire that takes into account both leisure-time and work-related physical activity. Waist circumference was measured and BMI was calculated for each participant.

RESULTS

For both men and women, we observed that within each BMI category (<25.0, 25-30 and >or=30.0 kg m(-2)), active participants had a lower waist circumference than inactive participants (P<0.001). In contrast, within each waist circumference tertile, BMI did not change across physical activity categories (except for women with an elevated waist circumference). Compared with active men with a low waist circumference, inactive men with an elevated waist circumference had a hazard ratio (HR) for future CHD of 1.74 (95% confidence interval (CI), 1.34-2.27) after adjusting for age, smoking, alcohol intake and parental history of CHD. In the same model and after further adjusting for hormone replacement therapy use, compared with active women with a low waist circumference, inactive women with an elevated waist circumference had an HR for future CHD of 4.00 (95% CI, 2.04-7.86).

CONCLUSION

In any BMI category, inactive participants were characterized by an increased waist circumference, a marker of abdominal adiposity, compared with active individuals. Physical inactivity and abdominal obesity were both independently associated with an increased risk of future CHD.