PT  - JOURNAL ARTICLE
AU  - Boulé, Normand G.
AU  - Weisnagel, S. John
AU  - Lakka, Timo A.
AU  - Tremblay, Angelo
AU  - Bergman, Richard N.
AU  - Rankinen, Tuomo
AU  - Leon, Arthur S.
AU  - Skinner, James S.
AU  - Wilmore, Jack H.
AU  - Rao, D.C.
AU  - Bouchard, Claude
TI  - Effects of Exercise Training on Glucose Homeostasis
AID  - 10.2337/diacare.28.1.108
DP  - 2005 Jan 01
TA  - Diabetes Care
PG  - 108--114
VI  - 28
IP  - 1
4099  - http://care.diabetesjournals.org/content/28/1/108.short
4100  - http://care.diabetesjournals.org/content/28/1/108.full
SO  - Diabetes Care2005 Jan 01; 28
AB  - OBJECTIVE—To determine the effect of a 20-week endurance training program in healthy, previously sedentary participants on measures derived from an intravenous glucose tolerance test (IVGTT). RESEARCH DESIGN AND METHODS—An IVGTT was performed before and after a standardized training program in 316 women and 280 men (173 blacks and 423 whites). Participants exercised on cycle ergometers 3 days per week for 60 sessions. The exercise intensity was progressively increased from 55% Vo2max for 30 min per session to 75% Vo2max for 50 min per session. RESULTS—Mean insulin sensitivity increased by 10% (P < 0.001) following the intervention, but the variability in the changes was high. Men had larger improvements than women (P = 0.02). Improvements in fasting insulin were transitory, disappearing 72 h after the last bout of exercise. There were also significant mean increases in the glucose disappearance index (3%, P = 0.02) and in glucose effectiveness (11%, P < 0.001), measures of glucose tolerance and of the capacity of glucose to mediate its own disposal, respectively. The acute insulin response to glucose, a measure of insulin secretion, increased by 7% in the quartile with the lowest baseline glucose tolerance and decreased by 14% in the quartile with the highest baseline glucose tolerance (P < 0.001). The glucose area below fasting levels during the IVGTT was reduced by 7% (P = 0.02). CONCLUSIONS—Although the effects of structured regular exercise were highly variable, there were improvements in virtually all IVGTT-derived variables. In the absence of substantial weight loss, regular exercise is required for sustained improvements in glucose homeostasis.