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.