The Gastrointestinal Exertional Heat Stroke Paradigm: Efficacy Of Acute Oral Glutamine Supplementation
Ogden, Henry B. (2020) The Gastrointestinal Exertional Heat Stroke Paradigm: Efficacy Of Acute Oral Glutamine Supplementation. Doctoral thesis, Plymouth Marjon University.
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Text (A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy - Marjon University)
THE GASTROINTESTINAL EXERTIONAL HEAT STROKE PARADIGM EFFICACY OF ACUTE ORAL GLUTAMINE SUPPLEMENTATION.pdf Download (3MB) | Preview |
Abstract
Exertional heat stroke (EHS) is the most severe form of heat related illness. In military settings, it is considered a largely preventable cause of morbidity, however, prevalence has remained high into the 21st Century. To support disease management, various policy documents provide occupational guidance on effective risk mitigation strategies, however, these can be criticised for focussing solely on the thermoregulatory pathology of the disease. The gastrointestinal (GI) EHS paradigm is a novel pathophysiological model that links EHS to luminal microbial translocation (MT) downstream of structural GI barrier integrity disturbance. Whilst this model is still in its infancy, recent investigations have established practical nutritional interventions that can support GI barrier integrity in populations at risk of EHS. The aims of this thesis were therefore to: (1) characterise the response of GI barrier integrity biomarkers to exertional�heat stress; and (2) examine the efficacy of acute oral L-glutamine (GLN) as a nutritional countermeasure to protect GI barrier integrity. From the experimental evidence reported in this thesis, several major conclusions were derived. First, GI barrier integrity can be reliably examined in blood samples taken at rest and following exertional-heat stress using the dual-sugar absorption test, intestinal�fatty acid binding protein and claudin-3 (chapter 4). Second, GI MT can be reliably examined in blood samples taken at rest and following exertional-heat stress using lipopolysaccharide binding protein and total 16S bacterial DNA, but not Bacteroides/total 16S DNA (chapter 4). Third, individuals with high-aerobic fitness experience blunted small intestinal epithelial injury and MT compared with untrained individuals during a fixed load exertional-heat stress test (chapter 5). Fourth, acute GLN supplementation (0.30, 0.60, 0.90 g·kg·FFM-1) causes mild dose-dependent GI symptoms at rest that generally lasted < 4 hours (chapter 6). Fifth, 0.30 g·kg·FFM-1 acute GLN supplementation does not protect GI permeability, small intestinal epithelial injury or MT when consumed 1-hour before either a low-intensity (chapter 7) or high-intensity (chapter 8) exertional-heat stress test. Taken together, GI barrier integrity loss reliably occurred in response to exertional-heat stress, a response that was blunted in individuals with high-aerobic fitness, but not following acute oral GLN supplementation.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Depositing User: | Ms Raisa Burton |
| Date Deposited: | 11 Oct 2022 14:49 |
| Last Modified: | 11 Oct 2022 14:49 |
| URI: | https://marjon.repository.guildhe.ac.uk/id/eprint/17718 |
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