Measurement of postprandial glucose fluxes in response to acute and chronic endurance exercise in healthy humans.

Dale J Morrison,Clinton R Bruce,Glenn D Wadley,Andrea Mari,Eleonora Grespan,Greg M Kowalski

doi:10.1152/ajpendo.00316.2017

Dale J Morrison, Clinton R Bruce + Show 4 more

Open Access

https://doi.org/10.1152/ajpendo.00316.2017

Copy DOI

Abstract

The effect of endurance exercise on enhancing insulin sensitivity and glucose flux has been well established with techniques such as the hyperinsulinemic clamp. Although informative, such techniques do not emulate the physiological postprandial state, and it remains unclear how exercise improves postprandial glycaemia. Accordingly, combining mixed-meal tolerance testing and the triple-stable isotope glucose tracer approach, glucose fluxes [rates of meal glucose appearance (Ra), disposal (Rd), and endogenous glucose production (EGP)] were determined following acute endurance exercise (1 h cycling; ~70% V̇o2max) and 4 wk of endurance training (cycling 5 days/wk). Training was associated with a modest increase in V̇o2max (~7%, P < 0.001). Postprandial glucose and insulin responses were reduced to the same extent following acute and chronic training. Interestingly, this was not accompanied by changes to rates of meal Ra, Rd, or degree of EGP suppression. Glucose clearance (Rd relative to prevailing glucose) was, however, enhanced with acute and chronic exercise. Furthermore, the duration of EGP suppression was shorter with acute and chronic exercise, with EGP returning toward fasting levels more rapidly than pretraining conditions. These findings suggest that endurance exercise influences the efficiency of the glucoregulatory system, where pretraining rates of glucose disposal and production were achieved at lower glucose and insulin levels. Notably, there was no influence of chronic training over and above that of a single exercise bout, providing further evidence that glucoregulatory benefits of endurance exercise are largely attributed to the residual effects of the last exercise bout.

Highlights

A cornerstone of public health promotion is encouraging people to participate in regular exercise, as it has been widely established that exercise confers numerous health benefits [50]
As a number of studies have demonstrated no additional benefit of endurance training above a single acute exercise bout for improving glucose metabolism when controlling for the residual effects of acute exercise [18, 38, 40], we examined glucose fluxes following an acute bout of endurance exercise and again after 4 wk of additional endurance training
Our findings show that in sedentary yet healthy young adults, both acute and chronic endurance training elicit comparable reductions in postprandial glycemia

Summary

Introduction

A cornerstone of public health promotion is encouraging people to participate in regular exercise, as it has been widely established that exercise confers numerous health benefits [50]. In relation to glucose metabolism, beneficial effects of endurance exercise in both healthy populations and those that are metabolically compromised, as in obesity and type 2 diabetes, includes enhancement to tissue insulin sensitivity [15, 20, 44, 51]; a benefit that is seen even after a single acute bout of endurance exercise [19]. It is important to highlight, that for exercise to have any meaningful effects on glucoregulation and diabetes prevention, improvements in fasting or postprandial glycemia and insulinemia should occur. This, in turn, should ease the workload of the ␤-cell while simultaneously minimizing the body’s exposure to hyperinsulinemia, which is known to have detrimental effects even when occurring in the absence of concomitant hyperglycemia [2, 14]

Objectives

Methods

Results

Conclusion