Bennett, S (2023) Carbohydrate periodisation via a “sleep low – train low” model and the impact of environmental heat stress: a practical and metabolomic exploration. Doctoral thesis, Liverpool John Moores University.

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Abstract

Endurance athletes have traditionally been advised to consume high carbohydrate intake before, during and after exercise to support high training loads and facilitate recovery. Accumulating evidence suggests periodically training with low carbohydrate availability, termed “train-low”, augments skeletal oxidative adaptations. Comparably, to account for increased carbohydrate utilisation during exercise in hot environmental conditions, nutritional guidelines advocate high carbohydrate intake. Recent evidence suggest heat stress induces oxidative adaptation in skeletal muscle, augmenting mitochondrial adaptation during endurance training. This thesis aimed to assess the efficacy of training with reduced carbohydrate and the impact of elevated ambient temperatures on performance and metabolism. Chapter 4 demonstrated 3-weeks of Sleep Low-Train Low (SL-TL) improves performance when prescribed and completed remotely. Chapter 5 implemented SL-TL in hot and temperate conditions, confirming SL-TL improves performance and substrate metabolism, whilst additional heat stress failed to enhance performance in hot and temperate conditions following the intervention. Chapters 6 and 7 optimised and implemented a novel in vitro skeletal muscle exercise model combining electrical pulse stimulation and heat stress. Metabolomics analysis revealed an ‘exercise’-induced metabolic response, with no direct metabolomic impact of heat stress. Chapter 8 characterised the systemic metabolomic response to acute exercise in the heat and following SL-TL and heat stress intervention revealing distinct metabolic signatures associated with exercise under heat stress. In summary, this thesis provides data supporting the application of the SL-TL strategy during endurance training to augment adaptation. Data also highlights the impact of exercise, environmental temperature and substrate availability on skeletal muscle metabolism and the systemic metabolome. Together, these data provide practical support of the efficacy of the SL-TL strategy to improve performance and adaptation whilst casting doubt on the utility of this approach in hot environments in endurance trained athletes.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Exercise; physiology; heat stress; metabolism; metabolomics; omics; cycling; triathlon; carbohydrate periodisation; adpatation; nutrition
Subjects:	R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions:	Sport & Exercise Sciences
SWORD Depositor:	A Symplectic
Date Deposited:	18 Apr 2023 15:03
Last Modified:	18 Apr 2023 15:03
DOI or ID number:	10.24377/LJMU.t.00019162
Supervisors:	Louis, J, Owens, D and Morton, J
URI:	https://researchonline.ljmu.ac.uk/id/eprint/19162

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