Does prior exercise affect oral glucose tolerance test results?
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BioMed Central
Open Access
Poster presentation
Does prior exercise affect oral glucose tolerance test results? C Alan Titchenal*1, Kelley Hatfield1, Michael Dunn1 and James Davis2 Address: 1Department of Human Nutrition, Food and Animal Sciences, University of Hawaii, 1955 East-West Rd., Honolulu, HI 96822, USA and 2Department of Complementary and Alternative Medicine, Clinical Research Center, University of Hawaii, Gold Bond Bldg, Suite 1015, Honolulu, HI 96813, USA Email: C Alan Titchenal* - [email protected] * Corresponding author
from 2008 International Society of Sports Nutrition Conference and Expo Las Vegas, NV, USA. 9–10 June 2008 Published: 17 September 2008 Journal of the International Society of Sports Nutrition 2008, 5(Suppl 1):P14
doi:10.1186/1550-2783-5-S1-P14
Proceedings of the Fifth International Society of Sports Nutrition (ISSN) Conference and Expo
Paul LaBounty and Jose Antonio Meeting abstracts – A single PDF containing all abstracts in this Supplement is available here.This abstract is available from: http://www.jissn.com/content/5/S1/P14 © 2008 Titchenal et al; licensee BioMed Central Ltd.
Background
Results
When oral glucose tolerance tests (OGTT) are repeated in individuals, relatively large variations in the magnitude of the blood glucose response often occur from one measurement occasion to another. Little is known about what causes this within-subject variability. One potential contributor may be the subject's prior extent of physical activity and/or the amount of stored glycogen present at the time of the OGTT. This research tested the effect of a bout of exercise (of the type known to significantly deplete muscle glycogen) performed within 24 hours prior to an OGTT on blood glucose and insulin responses.
Within each group, mean glucose AUC measured in capillary blood did not differ from that measured in venous blood. Also, there was no significant difference in capillary glucose AUC between the no-Ex and post-Ex conditions (mean +/- SD: 3364 +/- 1557 and 4318 +/- 1701 mg·min/dL, respectively; P = 0.10). However, insulin AUC values were significantly lower on post-Ex days (P = 0.03). When insulin levels were held constant (statistically), the mean glucose AUC levels were significantly greater the day after exercise (P = 0.03). The range of glycemic response among these athletes was substantial, with 2-hour capillary glucose AUC ranging from 845 to 5010 and 1348 to 6480 mg·min/dL in the no-Ex and post-Ex conditions, respectively.
Methods Ten male endurance athletes underwent an OGTT without prior exercise on one occasion (no-Ex) and after a glycogen-depleting bout of exercise the day prior to testing on another occasion (post-Ex). Venous blood was sampled at standard intervals (0, 15, 30, 45, 60, 90, and 120 minutes) following consumption of an OGTT beverage containing 50 grams of glucose. Capillary blood samples also were taken at the same intervals by finger stick to simulate the standard protocol used for glycemic index (GI) measurement. Venous and capillary blood
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