Prior Exercise and Postprandial Incretin Responses in Lean and Obese Individuals

ABSTRACTHEDEN, T. D., Y. LIU, M. L. KEARNEY, Y. PARK, K. C. DELLSPERGER, T. R. THOMAS, and J. A. KANALEY. Prior Exerciseand Postprandial Incretin Responses in Lean and Obese Individuals. Med. Sci. Sports Exerc., Vol. 45, No. 10, pp. 1897–1905, 2013.Purpose: The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) help regulatepostprandial triacylglycerol (TAG) and insulin concentrations, but the effects of acute aerobic exercise on GLP-1 or GIP responses areunclear. The purpose of this study was to determine whether reductions in postprandial TAG and insulin with exercise are associated withGLP-1 and GIP responses. Methods: Thirteen normal-weight (NW) and 13 obese (Ob) individuals participated in two, 4-d trials inrandomorderincludinganexercise(EX)andanoexercise(NoEX)trial. Dietwascontrolledduringbothtrials.TheEXtrialconsistedof1hof treadmill walking (55%–60% of V˙O 2peak ) during the evening of day 3 of the trial, 12 h before a 4-h mixed meal test on day 4, duringwhich frequent blood samples were collected to assess postprandial lipemia, glycemia, insulin, C-peptide, GIP, and GLP-1 responses.Insulin secretion was estimated using the insulinogenic index, and insulin clearance was estimated using the ratio of insulin to C-peptide.Results: Postprandial TAG were 29% lower after EX in Ob individuals (P G0.05) but were not significantly altered in NW individuals(P 90.05). The drop in postprandial HDL cholesterol was attenuated with EX in Ob individuals (P G0.05). Insulin responses were 14%lower after EX in Ob individuals (P G0.05), and this was associated with reduced insulin secretion (P G0.05), with no change in insulinclearance (P 90.05). Glucose, C-peptide, GIP, and GLP-1 were not different between trials. Conclusion: A 1-h bout of moderate-intensityaerobic exercise the night before a mixed meal attenuates TAG and insulin responses in Ob but not NW individuals, an effect not associ-atedwithalteredGLP-1orGIPresponses.KeyWords: GLUCAGON-LIKE PEPTIDE 1,GLUCOSE-DEPENDENTINSULINOTROPICPOLYPEPTIDE, INSULIN, PHYSICAL ACTIVITY, OBESITY, LIPEMIA