Markers of inflammation are inversely associated with V̇o2 max in asymptomatic men

Abstract

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), V̇o2 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 V̇o2 max after adjustment for age, body mass index, CHD risk factors, and lifestyle variables (physical activity level, percent body fat, and alcohol intake). V̇o2 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 V̇o2 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 V̇o2 max. In conclusion, higher circulating levels of IL-6, CRP, and fibrinogen are independently associated with lower V̇o2 max in asymptomatic men.