The acute and residual effect of a single exercise session on meal glucose tolerance in sedentary young adults

Abstract

The study goals were to (1) establish the variability in postprandial glucose control in healthy young people consuming a mixed meal and, then (2) determine the acute and residual impact of a single exercise bout on postprandial glucose control. In study 1, 18 people completed two similar mixed meal trials and an intravenous glucose tolerance test (IVGTT). There were strong test-retest correlations for the post-meal area under the curve (AUC) for glucose, insulin, and Cpeptide (r = 0.73-0.83) and the Matsuda insulin sensitivity index (ISI, r = 0.76), and between meal and IVGTT-derived ISI (r = 0.83). In study 2, 11 untrained young adults completed 3 trials. One trial (No Ex) was completed after refraining from vigorous activity for ≥3 days. On the other 2 trials, a 45-min aerobic exercise bout was performed either 17-hours (Prior Day Ex) or 1-hour (Same Day Ex) before consuming the test meal. Compared to No Ex and Prior Day Ex, which did not differ from one another, there were lower AUCs on the Same Day Ex trial for glucose (6%), insulin (20%) and C-peptide (14%). Thus, a single moderate intensity exercise session can acutely improve glycemic control but the effect is modest and short-lived.

Figure 1

Insulin sensitivity in young healthy people in Study 1. (a) Correlation between the Matsuda whole body insulin sensitivity index (ISI, arbitrary units) measured during two identical mixed meal tests. (b) Correlation between the minimal model-derived estimate of insulin sensitivity (SI, units = 10⁻⁴/min ×  μU/mL) during an intravenous glucose tolerance test (IVGTT) and the ISI from the first mixed meal test.

Figure 2

Postmeal responses in glucose, insulin, C-peptide, and nonesterified fatty acids in Study 2. Values shown as mean ± SEM for 11 people. *No Ex different from Same Day Ex trial; ^†Prior Day Ex different from Same Day Ex, P < 0.05.

Figure 3

Area under the curve for glucose, insulin, C-peptide, and fatty acids during the post meal period. Values shown as mean ± SEM for 11 people. *No Ex different from Same Day Ex trial; ^†Prior Day Ex different from Same Day Ex, P < 0.05. There were non significant trends for differences between Prior Day Ex versus Same Day Ex insulin (P = 0.059) and fatty acids (P = 0.092).

Figure 4

Postmeal responses in energy expenditure and fuel oxidation. Energy expenditure and the relative carbohydrate (CHO) oxidation were increased throughout the postmeal period relative to baseline but did not differ among trials.