Oxidative stress explains differences in large elastic artery compliance between sedentary and habitually exercising...

To determine whether oxidative stress contributes to differences in large elastic artery compliance between sedentary and habitually exercising postmenopausal women.

Carotid artery compliance was measured during acute intravenous infusions of saline (control) and supraphysiological doses of the potent antioxidant ascorbic acid (vitamin C) in sedentary (n = 15; 58 +/- 1 years) and endurance exercise-trained (n = 11, 59 +/- 1) healthy postmenopausal women.

Carotid artery compliance was 24% higher in the exercising versus sedentary women during control (P < 0.001). During ascorbic acid infusion, carotid artery compliance was increased by 28% in the sedentary women (1.29 +/- 0.12 to 1.60 +/- 0.12 mm/mm Hg x 10, P < 0.001 vs control) but was unchanged in exercising women (1.60 +/- 0.14 vs 1.48 +/- 0.14 mm/mm Hg x 10, P = 0.10), abolishing the habitual exercise-associated baseline difference. The change in compliance with ascorbic acid was most strongly related to maximal aerobic capacity (r = -0.64, P < 0.0001) and body fatness (r = 0.60, P < 0.0001) and was more modestly related to oxidized low-density lipoprotein, waist circumference, interleukin-6, total and low-density lipoprotein cholesterol (all r = 0.40 to 0.49, all P < 0.05), and high-density lipoprotein cholesterol (r = -0.48, P = 0.01). Carotid artery diameter, blood pressure, and heart rate were unaffected by ascorbic acid.

These results indicate that the greater large elastic artery compliance in habitually exercising compared with sedentary estrogen-deficient postmenopausal women may be mediated by an absence of oxidative stress, perhaps related in part to more favorable cardiovascular risk factors.