-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% V O2 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 (Con-GLU). 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 Ͻ 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 Ͻ 0.05). The plasma glucose response was greater (P Ͻ 0.03) and the plasma insulin response lower (P Ͻ 0.004) during ExGLU compared with ConGLU. There was a significantly higher (P Ͻ 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 ϭ Ϫ0.35, P Ͻ 0.03) and insulin (r ϭ Ϫ0.37, P Ͻ 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 THE IMMEDIATE POSTEXERCISE PERIOD appears to be associated with mild reversible insulin resistance, which is characterized by an attenuated insulin response and an increased glucose response to oral glucose (10,21,25,27,33,37,39,43). The physiological basis for the increased glucose response has been shown to be partly a function of greater release of glucose from the splanchnic tissues (20,30,39). Gut peptides and hormones of the enteroinsular axis may also play an important functional role in fuel homeostasis and contribute to maintaining a balance between energy utilization and mobilization. The metabolic role of peptides from the enteroinsular axis, including vasoactive intestinal peptide (VIP), gastric inhibitory polypeptide (GIP; also called glucose-dependent insulinotropic polypeptide), and glucagon-like peptide-1 (GLP-1), are known. However, the response of these peptides during recovery from exercise and the role they may play after glucose ingestion in the immediate postexercise period is less clear.VIP is secreted by the central (CNS) and peripheral (including enteric) nervous systems in response to duodenal acidification, gastric distention, and meal consumption (6, 40). Its actions incl...