Increased Fitness Attenuates Endothelial Dysfunction Following A High Fat Meal In Postmenopausal Women

Abstract

Endothelial dysfunction is a known predictor of coronary artery disease (CAD) and may be worsened in the postprandial state, particularly after ingestion of a high-fat meal. Post-menopausal status also confers a greater risk for the development of endothelial dysfunction and CAD, whereas cardiorespiratory fitness is positively associated with endothelial function. PURPOSE: To examine if increased fitness (VO2max) attenuates postprandial endothelial dysfunction that follows the ingestion of a high-fat meal challenge in sedentary post-menopausal women. METHODS: Fifteen sedentary post-menopausal women (Age=56.6 + 4.2 yr; BMI=27.0 + 4.9 kg/m2; % body fat=40.9 + 7.1%; VO2max=22.6 + 4.3 ml.kg-1.min-1; range =16.4-31.5) were admitted to the General Clinical Research Center on two occasions for VO2max and brachial artery flow mediated dilation testing. Subjects underwent an incremental VO2 max protocol and on a separate day underwent serial brachial artery flow mediated dilation measurements at baseline (after an overnight fast) and 2 and 4-hours after ingestion of a high-fat breakfast meal challenge (57% fat, 25% protein, and 18% carbohydrate). Percent flow-mediated dilation (% FMD) was quantified by comparing B-mode ultrasound images of the brachial artery at rest and during reactive hyperemia following 5-min of forearm occlusion with a blood pressure cuff at 50mmHg above systolic blood pressure. Measurements of brachial artery diameter were made by using computerized edge detection software. RESULTS: A significant relationship was observed between VO2max and %FMD at 2 hours (r=.52, p=0.047) and 4 hours (r=0.63, p= 0.012) postprandially. CONCLUSION: Fitness is associated with increased %FMD in post-menopausal women following a high fat meal challenge, with elevated fitness associated with an improved endothelial response in the postprandial period. This may be yet another mechanism by which increased cardio-respiratory fitness lowers cardiovascular risk.