Prior exercise does not alter the incretin response to a subsequent meal in obese women

Prior research has shown an increase in GLP-1 concentrations during exercise but this exercise bout was conducted postprandially. The purpose of this study was to examine the incretin response to a meal following an exercise bout of different intensities in obese subjects. Eleven women (BMI > 37.3 ± 7.0 kg/m2; Age 24.3 ± 4.6 year) participated in 3 counter- balanced study days, where a standardized meal was preceded by: (1) No exercise (NoEx), (2) ModEx (55% VO2max), and (3) IntEx (4 min (80% VO2max)/3 min (50% VO2max). Frequent blood samples were analyzed for glucose, lactate, insulin, glucagon, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and C-peptide concentrations throughout 280 min of testing. Glucose concentrations were not different between conditions during exercise or meals. There were no differences between conditions in insulin levels during exercise and recovery, but postprandial insulin incremental area under the curve was lower in ModEx vs. NoEx (p < 0.01). GIP and GLP-1 levels were not different between conditions during exercise, but during exercise recovery, GLP-1 concentrations were higher in ModEx vs. NoEx (p = 0.03). The meal increased the incretin responses (p < 0.01) but this response was not affected by prior exercise. Glucagon concentrations increased with exercise (p < 0.05) and continued to be elevated during recovery, with the greatest increase with IntEx compared with NoEx (p < 0.05). No differences between conditions were detected for hepatic insulin extraction, insulin secretion, or insulin sensitivity. Exercise prior to an evening meal has no impact on the incretin response to the subsequent meal, yet insulin concentrations were lower during the meals that followed exercise. Exercise intensity had no impact on this response.