Carbohydrate supplementation and the influence of breakfast on fuel use in hypoxia

Griffiths, A., Deighton, K., Boos, C. J., Rowe, J., Morrison, D. , Preston, T. , King, R. and O’Hara, J. P. (2021) Carbohydrate supplementation and the influence of breakfast on fuel use in hypoxia. Medicine and Science in Sports and Exercise, 53(4), pp. 785-795. (doi: 10.1249/MSS.0000000000002536) (PMID:33044437)

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Abstract

Purpose: This study investigated the effect of carbohydrate supplementation on substrate oxidation during exercise in hypoxia after pre-exercise breakfast consumption and omission. Methods: Eleven men walked in normobaric hypoxia (FiO2 ~11.7%) for 90-min at 50% of hypoxic V[Combining Dot Above]O2max. Participants were supplemented with a carbohydrate beverage (1.2g·min glucose) and a placebo beverage (both enriched with U-C6 D-glucose) after breakfast consumption and after omission. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate carbohydrate (exogenous and endogenous (muscle and liver)) and fat oxidation. Results: In the first 60-min of exercise, there was no significant change in relative substrate oxidation in the carbohydrate compared with placebo trial after breakfast consumption or omission (both p = 0.99). In the last 30-min of exercise, increased relative carbohydrate oxidation occurred in the carbohydrate compared with placebo trial after breakfast omission (44.0 ± 8.8 vs. 28.0 ± 12.3, p < 0.01) but not consumption (51.7 ± 12.3 vs. 44.2 ± 10.4, p = 0.38). In the same period, a reduction in relative liver (but not muscle) glucose oxidation was observed in the carbohydrate compared with placebo trials after breakfast consumption (liver: 7.7 ± 1.6% vs. 14.8 ± 2.3%, p < 0.01; muscle: 25.4 ± 9.4% vs. 29.4 ± 11.1%, p = 0.99) and omission (liver: 3.8 ± 0.8% vs. 8.7 ± 2.8%, p < 0.01; muscle: 19.4 ± 7.5% vs. 19.2 ± 12.2%, p = 0.99). No significant difference in relative exogenous carbohydrate oxidation was observed between breakfast consumption and omission trials (p = 0.14). Conclusion: In acute normobaric hypoxia, carbohydrate supplementation increased relative carbohydrate oxidation during exercise (> 60 min) after breakfast omission, but not consumption.

Item Type:Articles
Additional Information:The authors would like to thank Leeds Beckett University for funding this study.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Preston, Professor Tom and Morrison, Dr Douglas
Authors: Griffiths, A., Deighton, K., Boos, C. J., Rowe, J., Morrison, D., Preston, T., King, R., and O’Hara, J. P.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Medicine and Science in Sports and Exercise
Publisher:Lippincott, Williams & Wilkins
ISSN:0195-9131
ISSN (Online):1530-0315
Published Online:07 October 2020
Copyright Holders:Copyright © 2020 American College of Sports Medicine
First Published:First published in Medicine and Science in Sports and Exercise 53(4): 785-795
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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