Markers of inflammation are inversely associated with V̇O _{2 max} in asymptomatic men

We investigated whether markers of inflammation, including a cytokine (IL-6), acute-phase reactants [C-reactive protein (CRP) and fibrinogen], and white blood cell (WBC) count are associated with maximal O₂ consumption (V̇O₂ max) in men without coronary heart disease (CHD). In asymptomatic men (n = 172, 51 ± 9.3 yr old), V̇O _{2 max} was measured during a symptom-limited graded treadmill exercise test. Physical activity level was assessed by a standardized questionnaire. IL-6 and CRP were measured by immunoassays, fibrinogen by the Clauss method, and WBC count with a Coulter counter. IL-6 and CRP were logarithmically transformed to reduce skewness. Multivariable regression was used to assess whether markers of inflammation were associated with V̇O_{2 max} after adjustment for age, body mass index, CHD risk factors, and lifestyle variables (physical activity level, percent body fat, and alcohol intake). V̇O_{2 max} was 34.5 ml·kg^-1 ·min^-1 (SD 6.1). Log IL-6 (r = -0.38, P < 0.001), log CRP (r = - 0.40, P < 0.001), fibrinogen (r = -0.42, P < 0.001), and WBC count (r = -0.22, P = 0.004) were each correlated with V̇O_{2 max}. In separate multivariable linear regression models that adjusted for age, body mass index, CHD risk factors, and lifestyle variables, log IL-6 [β-coeff = -1.66 ± 0.63 (SE), P = 0.010], log CRP [β-coeff = -0.99 ± 0.33 (SE), P = 0.003], fibrinogen [β-coeff = -1.51 ± 0.44 (SE), P = 0.001], and WBC count [β-coeff = -0.52 ± 0.30 (SE), P = 0.088] were each inversely associated with V̇O_{2 max}. In conclusion, higher circulating levels of IL-6, CRP, and fibrinogen are independently associated with lower V̇O_{2 max} in asymptomatic men.