The effects of low and high glycemic index foods on exercise performance and beta-endorphin responses
Abstract
Τhe aim of this study was to examine the effects of the consumption of foods of various glycemic index values on performance, β-endorphin levels and substrate (fat and carbohydrate) utilization during prolonged exercise. Eight untrained healthy males underwent, in a randomized counterbalanced design, three experimental conditions under which they received carbohydrates (1.5 gr. kg-1 of body weight) of low glycemic index (LGI), high glycemic index (HGI) or placebo. Food was administered 30 min prior to exercise. Subjects cycled for 60 min at an intensity corresponding to 65% of VO2max, which was increased to 90% of VO2max, then they cycled until exhaustion and the time to exhaustion was recorded. Blood was collected prior to food consumption, 15 min prior to exercise, 0, 20, 40, and 60 min into exercise as well as at exhaustion. Blood was analyzed for β-endorphin, glucose, insulin, and lactate. The mean time to exhaustion did not differ between the three conditions (LGI = 3.2 ± 0.9 min; HGI = 2.9 ± 0.9 min; placebo = 2.7 ± 0.7 min). There was a significant interaction in glucose and insulin response (P < 0.05) with HGI exhibiting higher values before exercise. β-endorphin increased significantly (P < 0.05) at the end of exercise without, however, a significant interaction between the three conditions. Rate of perceived exertion, heart rate, ventilation, lactate, respiratory quotient and substrate oxidation rate did not differ between the three conditions. The present study indicates that ingestion of foods of different glycemic index 30 min prior to one hour cycling exercise does not result in significant changes in exercise performance, β-endorphin levels as well as carbohydrate and fat oxidation during exercise. © 2011 Jamurtas et al; licensee BioMed Central Ltd.Citation
Jamurtas, A.Z., Tofas, T., Fatouros, I. et al. (2011) The effects of low and high glycemic index foods on exercise performance and beta-endorphin responses, Journal of the International Society of Sports Nutrition, 8(15). https://doi.org/10.1186/1550-2783-8-15Publisher
Springer Science and Business Media LLCJournal
Journal of the International Society of Sports NutritionPubMed ID
22013987 (pubmed)Additional Links
https://jissn.biomedcentral.com/articles/10.1186/1550-2783-8-15Type
Journal articleLanguage
enDescription
© 2011 The Authors. Published by BMC. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1186/1550-2783-8-15ISSN
1550-2783EISSN
1550-2783ae974a485f413a2113503eed53cd6c53
10.1186/1550-2783-8-15
Scopus Count
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Except where otherwise noted, this item's license is described as Licence for published version: Creative Commons Attribution 4.0 International
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