Purpose: The relationship of both physical activity and predicted maximum o
xygen consumption ((V) over dot O-2max) with the clustering of metabolic ri
sk factors associated with the metabolic syndrome (MS) was examined within
711 employed middle-aged (46.9 +/- 7.8 yr) men. Methods: Metabolic markers
included fasting glucose, triglycerides, high-density lipoprotein cholester
ol, blood pressure, and BMI, defined by highest risk quintiles or clinicall
y relevant risk thresholds. Results: The prevalence and age-adjusted odds r
atios of all MS clusters were inversely graded across both higher physical
activity index (PAT) and cardiorespiratory fitness (CRF) categories. The ag
e-adjusted odds ratio for the clustering of clinically relevant metabolic m
arkers was 0.60 (95% CI 0.22-1.22) for subjects in the occasional/light PAI
, 0.32 (95% CI 0.12-0.82) for the moderate/moderately vigorous PAI, and 0.1
3 (95% CI 0.02-1.02) for the vigorous PAI when compared with subjects in th
e sedentary PAI (P < 0.05 for trend). The corresponding age-adjusted odds r
atio was 0.28 (95% CI 0.14-0.57) for subjects in the moderate fitness categ
ory and 0.12 (95% CI 0.05-0.32) for the highest fitness category compared w
ith those in the lowest fitness category (P < 0.001 for trend). Higher leve
ls of physical activity or CRF were also associated with significantly lowe
r age-adjusted odds ratios for the MS after exclusion of obesity in the MS
definition. Conclusion: Overall, these cross-sectional results suggest that
higher physical activity and predicted (V) over dot O-2max levels are asso
ciated with a decreased clustering of risk factors associated with the MS i
n middle-aged men of higher social class.