A Single Bout of Exercise at Higher Intensity Enhances Glucose Effectiveness in Sedentary Men

Abstract

Previous studies have shown that glucose effectiveness and insulin sensitivity are acutely enhanced by exercise at various intensities. The aim of this study was to determine the effects of a single bout of exercise at intensities recommended by the American Diabetes Association (ADA) and the American College of Sports Medicine (ACSM) on glucose uptake-specific glucose effectiveness (S(G)(2)*) and insulin sensitivity (S(I)(2)*). S(G)(2)* and S(I)(2)* were estimated by a two-compartment minimal model. Six healthy men (age, 28.5 +/- 2.0 yr) performed a stable-labeled frequently sampled iv glucose tolerance test (FSIGT) under three separate conditions: without any prior exercise, and immediately after single 20-min bouts of cycle ergometer exercise at an intensity of 50% and 70% of maximal oxygen uptake (Vo(2max)). The exercise intensities were close to the lower and upper boundaries recommended by the ADA and ACSM. Glucose disappearance constant (K(G)), S(G)(2)*, and S(I)(2)* increased after exercise in an intensity-dependent manner. Increases in S(G)(2)* (+237.1 +/- 50.5%), S(I)(2)* (+225.6 +/- 51.9%), and K(G) (+151.7 +/- 16.5%) following exercise at 70% Vo(2max) were statistically significant (P < 0.05), whereas those at 50% Vo(2max) were not. In conclusion, a single bout of exercise acutely improves S(I)(2)* and S(G)(2)* in individuals with normal glucose tolerance in an intensity-dependent manner.