Background: Cross-sectional relationships between moderate and vigorous physical activity and the metabolic syndrome (MS) were examined in the Whitehall II study of civil servants (age 45-68 years). We assessed cardiovascular fitness and body mass index (BMI) as possible mediators of the observed association.
Methods: Measures of 2-hour glucose, systolic blood pressure, fasting triglycerides, waist-hip ratio, and high density lipoprotein (HDL) cholesterol were obtained in 5153 white European participants. Participants in the most adverse sex-specific quintile for three or more of these risk factors were classified as having MS. Self-reported leisure-time physical activity was categorized into separate moderate and vigorous activity classes. BMI and resting heart rate (HR) were used to estimate body fatness and cardiovascular fitness respectively.
Results: The odds ratios (95% CI) for having the metabolic syndrome in the top categories of vigorous and moderate activity were 0.52 (95% CI: 0.40, 0.67) and 0.78 (95% CI: 0.63, 0.96) respectively, adjusted for age, sex, smoking, alcohol intake, socioeconomic status, and other activity. Adjustment for BMI and resting HR substantially attenuated both of the above associations.
Conclusions: Moderate and vigorous physical leisure-time activity are each associated with reduced risk of being classified with MS independently of age, smoking, and high alcohol intake. Both vigorous and moderate activities may be beneficial to the MS cluster of risk factors among middle-aged populations. Reduced BMI and increased cardiovascular fitness may be important mediators of this association for both intensities of activity.