The effects of body fat and fitness on vascular health

Abstract

It is currently unclear whether the negative effect of body fat on vascular health is due to low aerobic fitness. It is also unclear whether a decrease in body fat mediates improvements in vascular health that occur with aerobic exercise. The purposes of the following studies were to 1) evaluate the relationships of adiposity (percent body fat determined by dual energy x-ray absorptiometry) and aerobic fitness (VO2peak normalized to fat-free mass) with vascular health (i.e., systemic and vascular inflammation, leptin, central arterial stiffness; and femoral artery diameter (DFA), blood flow (BFFA), and shear rate), 2) evaluate the relationship of leg fat and fat-free mass (FFM) with DFA and BFFA, and 3) determine whether the effect of aerobic exercise training on vascular health is dependent on a reduction in adiposity. Forty-six pre-menopausal women (25-40 years old) were recruited for the cross-sectional study. C-reactive protein (CRP) was a significantly correlated with adiposity, but not VO2peak (R=0.46, P=0.002). VO2peak reduced the increase in CRP associated with an increase in % body fat (interaction effect, P=0.01). Leptin was correlated with adiposity (R=0.77, P<0.001), as well as CRP (r=0.36, P=0.01) and ICAM-1 (r=0.56, P<0.001). Aortic pulse wave velocity (aPWV) was significantly correlated with VO2peak, but not adiposity, (R=-0.42, P=0.02). DFA was significantly correlated with VO2peak (R=0.42, P=0.004). DFA and BFFA were correlated with leg FFM (r=0.28, P=0.03; r=0.26, P=0.06). For the exercise training study, thirteen sedentary women (33±4 yrs) were tested before and after 14 weeks of cycle exercise. aPWV and sICAM-1 did not change with training, whereas CRP was reduced by 35% (P=0.05). Leptin also decreased 20% (P=0.04). Resting DFA increased 11.7% (P<0.001) and shear rate decreased 28% (P=0.007). Taken together, these studies provide evidence that increased aerobic fitness is positively associated with, or positively affects, each of these measures. The results of these studies support the concept that aerobic fitness modifies the negative effect that body fat may have on vascular health.