The gastroenteroinsular response to glucose ingestion during postexercise recovery

1 Division of Metabolism and Endocrinology, School of Medicine, The Queen’s University of Belfast, Belfast, N. Ireland; 2 Schwartz Center for Metabolism and Nutrition, 3 Departments of Medicine, 4 Physiology, and 5 Nutrition, Case Western Reserve University School of Medicine, Cleveland, OH; and 6 National Coaching and Training Center, University of Limerick, Limerick, Ireland Submitted 17 October 2005 ; accepted in final form 5 January 2006 This study examined gastrointestinal hormone and peptide responses when glucose was ingested after prolonged exercise. Six endurance-trained male athletes ran on a treadmill for 2 h at 60% O 2 max . Immediately after the run, the athletes consumed 75 g of glucose in 250 ml of water (ExGLU) or flavored water as a placebo control (ExPL). On a separate visit, the athletes rested for 2 h and then consumed glucose (ConGLU). During the first 60 min of recovery from exercise alone (ExPL), plasma vasoactive intestinal peptide (VIP), gastrin, and glucagon-like peptide-1 (GLP-1) all increased significantly, whereas glucose, insulin, and gastric inhibitory polypeptide (GIP) were unchanged from the immediate postexercise value. When glucose was ingested after exercise (ExGLU), glucose, insulin, VIP, gastrin, GLP-1, and GIP were all increased ( P < 0.01). However, when glucose was ingested after resting for 2 h (ConGLU), VIP levels were unaffected, although glucose, insulin, gastrin, GLP-1, and GIP levels increased ( P < 0.05). The plasma glucose response was greater ( P < 0.03) and the plasma insulin response lower ( P < 0.004) during ExGLU compared with ConGLU. There was a significantly higher ( P < 0.01) VIP response during the initial period of recovery in ExGLU than there was with both ExPL and ConGLU. Plasma VIP showed a modest negative correlation with circulating glucose ( r = –0.35, P < 0.03) and insulin ( r = –0.37, P < 0.03) during the ExGLU recovery period. In summary, when glucose is ingested after prolonged exercise, there is mild insulin resistance and a corresponding rapid transitory increase in plasma VIP. These data suggest that VIP may play an important glucoregulatory role when glucose is ingested during the immediate postexercise recovery period. insulin resistance; gut peptides; exercise performance; carbohydrate Address for reprint requests and other correspondence: J. P. Kirwan, Case Western Reserve University School of Medicine, Schwartz Center for Metabolism and Nutrition, Bell Greve Bldg., Rm G-733B, 2500