Publications

Abstract

Physical training causes hypoinsulinemia and enhanced insulin sensitivity. Insulin sensitivity is also enhanced by a single bout of exercise. However, changes in beta-cell responsiveness with acute exercise are ill defined. To clarify these relationships intravenous glucose tolerance tests were performed in 1) physically trained rats (3 different levels), 48 h after the last bout of exercise; 2) untrained rats, 0.5, 4, and 24 h after a single bout of exercise; or 3) sedentary control rats. The total area under the glucose-stimulated insulin response curve (GSIR) was negatively correlated with total distance run during training (r = -0.45, P less than 0.05), whereas glucose tolerance was improved (P less than 0.005 vs. controls) with intensive training. GSIR was suppressed by 38% (P less than 0.01 vs. controls) 0.5 h after a single bout of exercise. This effect persisted for 4 h but was not present after 24 h. These results indicate that a single bout of exercise induces suppression of GSIR which lasts less than 24 h. In contrast, physical training induces prolonged suppression (for at least 48 h) of GSIR, proportional to the intensity of training, and improved glucose tolerance.