The Flow-Mediated Dilation Response to Acute Exercise in Overweight Men

Abstract

INTRODUCTION Inflammation has been found to play a role in the etiology of coronary heart disease as well as induce endothelial dysfunction. Brachial artery flow-mediated dilation (FMD) is a measure of nitric oxide dependent vasodilation and represents a non-invasive measurement of endothelial function. The aim of the present study was to 1) investigate the interaction of inflammatory biomarkers on the FMD response to acute exercise in overweight men and 2) determine if FMD following moderate intensity acute exercise is reproducible.

METHODS Sixteen overweight men ages 46-68 years were classified as either being active or inactive. Subjects performed three acute exercise treatments (25%, 50%, and 75% VO2peak), separated by at least two days apart. The 50% intensity was repeated in 9 subjects to investigate FMD reproducibility in response to acute exercise. Following the initial insertion of a venous catheter, brachial artery Flow-Mediated Dilation (FMD) and subsequent blood samples were taken pre exercise and every hour for three hours thereafter.

RESULTS The active group displayed a 24% increase (p=.034) in FMD following acute exercise compared to a 32% decrease (p=.010) in FMD observed in the inactive group. Both groups exhibited an elevated concentration of IL-6 following moderate (50% VO2) and high (75% VO2) intensity acute exercise (p<.001 and p<.001, respectively), whereas no change (p=.669) in IL-6 following low intensity (25% VO2) exercise in either group was observed. No differences in TNF- were observed between groups (p=.433) or in response to acute exercise (p=.584). A significant FMD correlation (r = 0.531; p=.008) following exercise between trial 1 and trial 2 was found.

CONCLUSION FMD following exercise appears to be as reproducible as resting controlled conditions. In addition, the FMD response to acute exercise is enhanced in overweight active men when compared to their inactive counterparts; however, inflammation did not provide insight into the physiological mechanisms associated with the improvement of FMD.

This research was supported by the Gatorade Sport Science Institute and Indiana University HPER Research Grant-in-Aids.