A single bout of exercise at higher intensity enhances glucose effectiveness in sedentary men

Objective: 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. Design: 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. Results: 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. Conclusions: 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.