Incretin response to acute exercise of differing intensities in obese women

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The purpose of this study was to determine the incretin response to an acute continuous, moderate intensity (ModEx) and high-intensity interval (IntEx) exercise bout in obese women, and how previous exercise affects the glycemic and incretin response to a subsequent dinner meal. Sedentary, obese women (BMI>30kg/m2 ; 18-35 yr) participated in three conditions in a randomized, counterbalanced design: 1) No exercise/rest (NoEx), 2) continuous, moderate intensity exercise at 55% VO2max (ModEx), and 3) high-intensity aerobic interval exercise at 4 min 80% VO2max/3 min 50% VO2max (IntEx), followed by a standardized mixed dinner meal (800kcal; 65% CHO, 20% fat, 15% protein). Blood was sampled every 10 min for the first 160 min and then every 30 min for the final 2 h of the study day. Samples were analyzed for glucose, lactate, insulin, glucagon, GLP-1, GIP, and C-Peptide. Lactate concentrations increased during exercise in ModEx (6.2±0.7 mg/dL) and even greater in IntEx (15.4±2.5 mg/dL) conditions compared to NoEx (3.7±0.2 mg/dL) (p=0.01; p=0.001, respectively) which persisted into recovery (p=0.01). Glucose concentrations were not different between groups during exercise (p=0.38). Mean GIP and GLP-1 was not different between groups during exercise (p>0.05), but during recovery, GLP-1 concentrations were higher in ModEx condition compared to NoEx (p=0.03). In response to a mixed dinner meal, insulin and C-peptide iAUC was lower in ModEx condition compared to NoEx (p=0.002; p=0.005, respectively). No differences between groups were detected for glucose, GIP, GLP-1, hepatic insulin extraction, insulin secretion, or insulin sensitivity following the meal. Regardless of intensity, GLP-1 and GIP concentrations were increased during the latter stages of exercise, accompanied by a decrease in plasma insulin concentrations; opposite of the postprandial insulinotropic response previously associated with the incretin hormones. Insulin concentrations were reduced more so in the ModEx condition which may be attri