Cardiorespiratory Fitness and Components of the Metabolic Syndrome in Sedentary Men

Objective: To investigate the relationships between fitness and components of the metabolic syndrome in sedentary men. Subjects and Methods: 39 subjects (34-53 years) were evaluated for fitness ((V) over dotO(2max)) and anthropometric, metabolic, and skeletal muscle phenotypes. (V) over dotO(2max) was assessed on a bicycle ergometer whereas other variables were obtained from an oral glucose tolerance test (OGTT), hydrostatic weighing, and a muscle biopsy. Results: Pearson and partial correlations adjusted for fat mass (FM), waist circumference (WC), muscle enzyme activities (citrate synthase (CS), cytochrome c oxidase (COX)), and capillary density were used to investigate the independent relationships between variables. Negative correlations between (V) over dotO(2max) and WC as well as blood pressure and OGTT test were observed. When adjusted for FM, correlations remained between (V) over dotO(2max) and WC (r = -0.46, p < 0.01) and systolic blood pressure (r = -0.35, p < 0.05). When adjusted for WC and CS activity, all correlations were lost except for high-sensitivity C-reactive protein (hs-CRP) (r = -0.34, p < 0.05) which remained when adjusted for CS activity. Adjustment for COX activity failed to remove correlations with hs-CRP (r = -0.36, p < 0.05), age (r = 0.34, p < 0.05), WC (r = -0.35, p < 0.05), and blood pressure. Negative correlations persisted when fitness was adjusted for the mean number of capillaries. Conclusion: The effects of fitness on components of the metabolic syndrome in sedentary men are explained by abdominal obesity and muscle phenotypes.