The Effect of Aerobic Exercise Traning on Endothelial Function in African American and Caucasian Postmenopausal Women

Endothelial dysfunction measured via flow mediated dilation (FMD) is an early marker of atherogenesis, and may be associated with increased cardiovascular disease risk. Conversely, aerobic exercise training as an intervention has been shown to improve endothelial function in mostly Caucasian (C) populations, but has not been evaluated in African Americans (AA) or following a high fat meal challenge. Purpose: To determine the effect of aerobic exercise training on baseline and postprandial endothelial function following a high fat meal in healthy sedentary African American and Caucasian postmenopausal women. Methods: Eight African American (age= 55.8 yrs. + 1.7, VO 2 peak= 21.0 + 3.9 ml/kg/min, BMI= 30.1+ 6.3kg/m 2 ) and 18 Caucasian (age= 57.2 yrs. + 5.9, VO 2 peak= 21.8 + 3.7 ml/kg/min, BMI= 29.3 + 5.2 kg/m 2 ) sedentary postmenopausal women underwent FMD (at rest, 2 and 4 hours following a high fat meal) at baseline and after 12 weeks of exercise training. FMD was quantified by comparing B-mode ultrasound images of the brachial artery at rest and following reactive hyperemia after 5-minutes of forearm occlusion. Subjects participated in 12 weeks of aerobic exercise training four times each week, two days below the lactate threshold (RPE=10-12), and two days above the lactate threshold (RPE=15-17). Results: Despite a significant improvement in VO 2 peak (AA=13.5% vs. C=18.3%), aerobic exercise training did not significantly improve baseline FMD in African American (5.77% to 5.68%, p= 0.950) or Caucasian postmenopausal women (5.68% to 6.64%, p=0.267). However, in subjects who had impaired endothelial function at baseline (FMD <4.5%), there was a significant improvement in FMD following exercise training (2.22% to 6.16%, p=0.007). Additionally, there was no significant improvement in percent fat, BMI, waist circumference or postprandial endothelial function following the exercise intervention. Conclusions: The results of the present study suggest that exercise training may be most beneficial to postmenopausal women with endothelial dysfunction, but does not attenuate the effects of a high fat meal on postprandial endothelial function. DEDICATION I would like to dedicate this dissertation to my parents John and Leoda Swift for everything that they have done over the course of my lifetime.

Note: Abstract extracted from PDF text