Copyright @ 2006 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Exercise-Induced Changes in Insulin Action and Glycogen Metabolism in Elderly Adults

decreased insulin resistance, recommendations for exercise training are not specific for age or level of obesity. Therefore, we examined the influence of moderate-intensity (50 % of V̇O2max) exercise training (MI) versus high-intensity (75 % of V̇O2max) exercise training (HI) on insulin-stimulated glucose disposal (ISGD) in elderly individuals. Methods: Following medical examinations, 21 overweight (body mass index = 29 T 1 kgImj2) elderly (74 T 1 yr) subjects were randomized to 1) HI, 2) MI, or a 3) nonexercising control group. Subjects enrolled in HI or MI completed a 12-wk exercise training regimen designed to expend 1000 kcalIwkj1. ISGD was assessed using a hyperinsulinemic, euglycemic clamp pre- and postintervention. ISGD was corrected for hepatic glucose production (glucose Ra) using a constant rate infusion of [6,6-2H2]glucose and determined during the last 30 min of the clamp by subtracting glucose Ra from the exogenous glucose infusion rate. Nonoxidative glucose disposal was calculated using indirect calorimetry. Body composition testing was completed using dual energy x-ray absorptiometry. Results: ISGD increased by approximately 20 % with HI ( $ of 1.4 T 0.5 mgIkgj1 FFMIminj1). However, ISGD did not change ( $ of j0.4 T 0.1 mgIkgj1 FFMIminj1) with MI and was not different ( $ of j0.2 T 0.1 mgIkgj1 FFMIminj1) in the control group. Nonoxidative glucos