Endothelial function following glucose ingestion in adults with prediabetes: Role of exercise intensity

Abstract

Objective: To determine whether high intensity exercise (HIE) would improve endothelial function more than an isocaloric bout of moderate intensity exercise (MIE) following glucose ingestion in adults with prediabetes.

Methods: Twelve subjects with prediabetes completed all three conditions: time-course matched control and isocaloric exercise (∼200 kcal) at moderate (MIE; at lactate threshold) and high intensity (HIE; 75% of difference between lactate threshold and VO2 peak). Brachial artery flow-mediated dilation (FMD) was measured before exercise (baseline), within 30 min postexercise, and 1 and 2 hr following a 75 g oral glucose tolerance test (OGTT). Plasma F2-isoprostanes were also assessed during the protocol (i.e., baseline to 2 hr OGTT) as a biomarker of oxidative stress.

Results: MIE reduced postexercise F2-isoprostanesAUC compared with time-course matched control and HIE. Although exercise had no statistical effect on FMD postexercise or during the OGTT, elevations in FMDAUC after MIE and HIE were associated with reduced postexercise F2-isoprostanesAUC .

Conclusions: Exercise at either intensity had no effect on FMD immediately postexercise following glucose administration. However, individuals with reduced oxidative stress responses to exercise had greater exercise-induced improvement in FMD. Further work is required to identify the mechanism by which exercise alters oxidative stress to enhance endothelial function.

Conflict of interest statement

Conflict of Interest: The authors declare no conflict of interest.

© 2016 The Obesity Society.

Figures

Figure 1

Study schematic. FMD = flow-mediated dilation. OGTT = oral glucose tolerance test.

Figure 2

Effect of exercise intensity on post-prandial metabolism. Plasma glucose (a) and insulin (b) concentrations. Data are expressed as mean ± SEM. Data were previously reported (13), but are highlighted here for ease of interpretation.

Figure 3

Effect of exercise intensity on endothelial function. FMD time-course responses (a). Area under the curve (AUC) for FMD (b). FMD = flow-mediated dilation. FMD was calculated as the percent change from pre- to post-occulsion diameter. Data are expressed as mean ± SEM.

Figure 4

Effect of exercise intensity on oxidative stress and associations with endothelial function. F2-isoprostanes time-course responses (a). Area under the curve (AUC) for F2-isoprostanes (b). Correlation between isoprostanes and vascular function following MIE (moderate intensity exercise; (c) and HIE (high intensity exercise; (d)). Change (Δ) between exercise and control conditions. FMD = flow-mediated dilation and reflects endothelial function. *Compared to CON, P<0.05. ^Compared to MIE, P<0.05. #Condition effect compared with CON, P<0.05. Data are expressed as mean ± SEM.