Effects of Exercise Training on Glucose Homeostasis

Effects of Exercise Training on Glucose Homeostasis The HERITAGE Family Study Normand G. Boulé , MA 1 , S. John Weisnagel , MD 1 2 , Timo A. Lakka , MD, PHD 3 4 , Angelo Tremblay , PHD 1 , Richard N. Bergman , PHD 5 , Tuomo Rankinen , PHD 3 , Arthur S. Leon , MD 6 , James S. Skinner , PHD 7 , Jack H. Wilmore , PHD 8 , D.C. Rao , PHD 9 and Claude Bouchard , PHD 3 1 Division of Kinesiology, Laval University, Ste-Foy, Québec, Canada 2 Diabetes Research Unit, Centre de Recherche sur les Maladies Lipidiques, Laval University, Ste-Foy, Québec, Canada 3 Human Genomics Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana 4 Kuopio Research Institute of Exercise Medicine and the Department of Physiology, University of Kuopio, Kuopio, Finland 5 Keck School of Medicine, University of Southern California, Los Angeles, California 6 Laboratory of Physiological Hygiene and Exercise Science, Division of Kinesiology, University of Minnesota, Minneapolis, Minnesota 7 Department of Kinesiology, Indiana University, Bloomington, Indiana 8 Department of Health and Kinesiology, Texas A&M University, College Station, Texas 9 Departments of Genetics and Psychiatry, Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri Address correspondence and reprint requests to S. John Weisnagel, MD, FRCPC, Diabetes Research Unit, S-27, Centre Hospitalier Université Laval, Laval University, 2705 Boulevard Laurier Sainte-Foy, Québec, Canada, G1V 4G2. E-mail: john.weisnagel{at}kin.msp.ulaval.ca Abstract 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% V o 2max for 30 min per session to 75% V o 2max 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