Effect of timing of energy and carbohydrate replacement on post-exercise insulin action

The nutritional environment surrounding an exercise bout modulates post-exercise insulin action. The purpose of this study was to determine how timing energy and carbohydrate replacement proximate to an exercise bout influences exercise-enhanced insulin action. To create an appropriate baseline, sen...

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Bibliographic Details
Published in:	Applied physiology, nutrition, and metabolism Vol. 32; no. 6; p. 1139
Main Authors:	Stephens, Brooke R, Sautter, Jeffrey M, Holtz, Kaila A, Sharoff, Carrie G, Chipkin, Stuart R, Braun, Barry
Format:	Journal Article
Language:	English
Published:	Canada 01-12-2007
Subjects:	Absorptiometry, Photon Adult Algorithms Anaerobic Threshold Blood Glucose - metabolism Body Composition - physiology Cross-Over Studies Dietary Carbohydrates - pharmacology Energy Intake - physiology Energy Metabolism - drug effects Energy Metabolism - physiology Exercise - physiology Female Glycerol - blood Humans Insulin - blood Insulin - physiology Kinetics Lipid Metabolism - drug effects Lipid Metabolism - physiology Liver - drug effects Liver - metabolism Male Time Factors
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Summary:	The nutritional environment surrounding an exercise bout modulates post-exercise insulin action. The purpose of this study was to determine how timing energy and carbohydrate replacement proximate to an exercise bout influences exercise-enhanced insulin action. To create an appropriate baseline, sensitivity to insulin was reduced in 9 healthy young men (n=6) and women (n=3) by 2 days of energy surplus and detraining. Then, insulin action (glucose uptake per unit plasma insulin) was assessed by stable isotope dilution during a continuous glucose infusion 12 h after a standardized meal under 4 conditions. In 3 conditions, the meal replaced the energy and carbohydrate expended during an exercise bout (62.9+/-2.8 min cycle ergometry at 65% VO2 peak followed by ten 30 s sprints). The meal was given before (Pre), immediately after (ImmPost), or 3 h after exercise (Delay). The 4th condition was a no-exercise control (Control). Data were analyzed using linear mixed-effects models with planned contrasts. Relative to Control, insulin action increased by 22% in Pre (p=0.05), 44% in ImmPost (p<0.01), and 19% in Delay (p=0.09). Non-oxidative disposal was higher, and oxidative disposal was lower in ImmPost relative to Control and Pre (p<0.05). Hepatic glucose production was suppressed by the infusion to a greater extent in Pre and Delay (76.9%+/-8.8% and 81.2%+/-4.7%) compared with ImmPost (64.7%+/-10.0%). A bout of exercise enhances insulin action even when expended energy and carbohydrate are replaced. Further, timing of energy and carbohydrate consumption subtly modulates the effectiveness of exercise to enhance insulin action.
ISSN:	1715-5312
DOI:	10.1139/H07-126