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

Abstract

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 (SG2*) and insulin sensitivity (S I2*). SG2* and S I2* 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 (V̇O2max). The exercise intensities were close to the lower and upper boundaries recommended by the ADA and ACSM. Results: Glucose disappearance constant (KG), SG2*, and SI2* increased after exercise in an intensity-dependent manner. Increases in SG2* (+237.1 ± 50.5%), SI2* (+225.6 ± 51.9%), and KG (+151.7 ± 16.5%) following exercise at 70% V̇O2max were statistically significant (P < 0.05), whereas those at 50% V̇O2max were not. Conclusions: In conclusion, a single bout of exercise acutely improves SI2* and SG2* in individuals with normal glucose tolerance in an intensity-dependent manner. Copyright © 2005 by The Endocrine Society.