Effects of Training on Postprandial Flow Mediated Dilation

Abstract

PURPOSE: The purpose of this study was to determine if regular endurance training (≊3-6 years) has a protective effect on vascular endothelial function following the consumption of a high-fat meal. METHODS: Healthy, young males (21 ±2 years) were classified as trained (n=10, 75±5 ml/kg/min) or untrained (n=10, 47±7 ml/kg/min) as determined by oxygen consumption. Body composition was measured via bioelectrical impedance analysis to determine fat-free mass and fat mass. Flow mediated dilation (FMD) of the brachial artery following reactive hyperemia was determined before, 2-, and 4-hours after the consumption of high-fat meal using Doppler ultrasound. Blood was drawn to determine fasting and postprandial blood lipid levels. The high fat meal was a commercially available fast-food breakfast meal composed of 1050 calories, 66 gfat, 21.5 g saturated fat, and 330 mg cholesterol. RESULTS: FMD prior to the high fat meal (≊9%) was not significantly different between groups (p=0.398). FMD was significantly reduced at 2- (35% and 36% for trained and untrained, respectively; p<0.001) and 4-hours (21% and 36% for trained and untrained, respectively; p<0.001) postprandial compared to baseline. The FMD response was not significantly different between groups after the meal at either time point (p=0.119). Serum TG increased at 2- (45% and 79% for trained and untrained, respectively; p<0.001) and 4-hours (55% and 92% for trained and untrained, respectively; p<0.001) from baseline in both groups. LDL-C was reduced at 4-hours (6%; p=0.05) in trained subjects, and 2- and 4-hours (19% and 11%, respectively; p≤0.01) in untrained subjects from baseline. HDL-C was reduced at 2-hours (1.6% and 4.9% in trained and untrained, respectively; p=0.024) in both groups but returned back to baseline levels by 4-hours. No significant differences were found between groups on any lipid marker at any time point. FMD was not significantly correlated to the blood lipid levels at baseline, 2-, or 4-hours. CONCLUSIONS: In conclusion, a HFM significantly reduced FMD for up to four-hours in trained and untrained individuals. Consistent endurance training did not prevent the transient reductions in vascular function after the ingestion of a single high-fat meal.