The Effect of Blood Ketone Concentration and Exercise Intensity on Exogenous Ketone Oxidation Rates in Athletes.

Autor:	Dearlove DJ; The Department of Physiology, Anatomy and Genetics, The University of Oxford, Oxford, UNITED KINGDOM., Harrison OK; The Department of Physiology, Anatomy and Genetics, The University of Oxford, Oxford, UNITED KINGDOM., Hodson L; Oxford Centre for Diabetes, Endocrinology and Metabolism, and the Oxford NIHR Biomedical Research Centre, The University of Oxford, Oxford, UNITED KINGDOM., Jefferson A; Micron Advanced Imaging Consortium, The University of Oxford, Oxford, UNITED KINGDOM., Clarke K; The Department of Physiology, Anatomy and Genetics, The University of Oxford, Oxford, UNITED KINGDOM., Cox PJ; The Department of Physiology, Anatomy and Genetics, The University of Oxford, Oxford, UNITED KINGDOM.
Jazyk:	angličtina
Zdroj:	Medicine and science in sports and exercise [Med Sci Sports Exerc] 2021 Mar 01; Vol. 53 (3), pp. 505-516.
DOI:	10.1249/MSS.0000000000002502
Abstrakt:	Introduction: Exogenous ketones potentially provide an alternative, energetically advantageous fuel to power exercising skeletal muscle. However, there is limited evidence regarding their relative contribution to energy expenditure during exercise. Furthermore, the effect of blood ketone concentration and exercise intensity on exogenous ketone oxidation rates is unknown. Methods: Six athletes completed cycling ergometer exercise on three occasions within a single-blind, random-order controlled, crossover design study. Exercise duration was 60 min, consisting of 20-min intervals at 25%, 50%, and 75% maximal power output (WMax). Participants consumed (i) bitter flavored water (control), (ii) a low-dose β-hydroxybutyrate (βHB) ketone monoester (KME; 252 mg·kg BW-1, "low ketosis"), or (iii) a high-dose βHB KME (752 mg·kg BW-1, "high ketosis"). The KME contained a 13C isotope label, allowing for the determination of whole-body exogenous βHB oxidation rates through sampled respiratory gases. Results: Despite an approximate doubling of blood βHB concentrations between low- and high-ketosis conditions (~2 mM vs ~4.4 mM), exogenous βHB oxidation rates were similar at rest and throughout exercise. The contribution of exogenous βHB oxidation to energy expenditure peaked during the 25% WMax exercise intensity but was relatively low (4.46% ± 2.71%). Delta efficiency during cycling exercise was significantly greater in the low-ketosis (25.9% ± 2.1%) versus control condition (24.1% ± 1.9%; P = 0.027). Conclusions: Regardless of exercise intensity, exogenous βHB oxidation contributes minimally to energy expenditure and is not increased by elevating circulating concentrations greater than ~2 mM. Despite low exogenous βHB oxidation rates, exercise efficiency was significantly improved when blood βHB concentration was raised to ~2 mM. (Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American College of Sports Medicine.)
Databáze:	MEDLINE
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