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dc.contributor.authorDearlove, David J
dc.contributor.authorHoldsworth, David
dc.contributor.authorKirk, Tom
dc.contributor.authorHodson, Leanne
dc.contributor.authorCharidemou, Evelina
dc.contributor.authorKvalheim, Eline
dc.contributor.authorStubbs, Brianna
dc.contributor.authorBeevers, Andrew
dc.contributor.authorGriffin, Julian L
dc.contributor.authorEvans, Rhys
dc.contributor.authorRobertson, Jeremy
dc.contributor.authorClarke, Kieran
dc.contributor.authorCox, Pete J
dc.date.accessioned2022-01-04T11:58:02Z
dc.date.available2022-01-04T11:58:02Z
dc.date.issued2021
dc.date.submitted2021-06-07
dc.identifier.issn2296-858X
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/331843
dc.description.abstractPurpose: In this study, we determined ketone oxidation rates in athletes under metabolic conditions of high and low carbohydrate (CHO) and fat availability. Methods: Six healthy male athletes completed 1 h of bicycle ergometer exercise at 75% maximal power (WMax) on three occasions. Prior to exercise, participants consumed 573 mg·kg bw-1 of a ketone ester (KE) containing a 13C label. To manipulate CHO availability, athletes undertook glycogen depleting exercise followed by isocaloric high-CHO or very-low-CHO diets. To manipulate fat availability, participants were given a continuous infusion of lipid during two visits. Using stable isotope methodology, β-hydroxybutyrate (βHB) oxidation rates were therefore investigated under the following metabolic conditions: (i) high CHO + normal fat (KE+CHO); (ii) high CHO + high fat KE+CHO+FAT); and (iii) low CHO + high fat (KE+FAT). Results: Pre-exercise intramuscular glycogen (IMGLY) was approximately halved in the KE+FAT vs. KE+CHO and KE+CHO+FAT conditions (both p < 0.05). Blood free fatty acids (FFA) and intramuscular long-chain acylcarnitines were significantly greater in the KE+FAT vs. other conditions and in the KE+CHO+FAT vs. KE+CHO conditions before exercise. Following ingestion of the 13C labeled KE, blood βHB levels increased to ≈4.5 mM before exercise in all conditions. βHB oxidation was modestly greater in the KE+CHO vs. KE+FAT conditions (mean diff. = 0.09 g·min-1, p = 0.03; d = 0.3), tended to be greater in the KE+CHO+FAT vs. KE+FAT conditions (mean diff. = 0.07 g·min-1; p = 0.1; d = 0.3) and were the same in the KE+CHO vs. KE+CHO+FAT conditions (p < 0.05; d < 0.1). A moderate positive correlation between pre-exercise IMGLY and βHB oxidation rates during exercise was present (p = 0.04; r = 0.5). Post-exercise intramuscular βHB abundance was markedly elevated in the KE+FAT vs. KE+CHO and KE+CHO+FAT conditions (both, p < 0.001; d = 2.3). Conclusion: βHB oxidation rates during exercise are modestly impaired by low CHO availability, independent of circulating βHB levels.
dc.languageen
dc.publisherFrontiers Media SA
dc.subjectMedicine
dc.subjectketone
dc.subjectketosis
dc.subjectexogenous ketosis
dc.subjectoxidation
dc.subjectexercise
dc.titleβ-Hydroxybutyrate Oxidation in Exercise Is Impaired by Low-Carbohydrate and High-Fat Availability.
dc.typeArticle
dc.date.updated2022-01-04T11:58:01Z
prism.publicationNameFront Med (Lausanne)
prism.volume8
dc.identifier.doi10.17863/CAM.79293
dcterms.dateAccepted2021-10-25
rioxxterms.versionofrecord10.3389/fmed.2021.721673
rioxxterms.versionVoR
rioxxterms.licenseref.urihttp://creativecommons.org/licenses/by/4.0/
dc.identifier.eissn2296-858X
cam.issuedOnline2021-11-25


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