Please use this identifier to cite or link to this item: http://bura.brunel.ac.uk/handle/2438/10609
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dc.contributor.advisorGonzalez-Alonso J-
dc.contributor.authorTrangmar, Steven John-
dc.date.accessioned2015-04-21T10:53:27Z-
dc.date.available2015-04-21T10:53:27Z-
dc.date.issued2015-
dc.identifier.urihttp://bura.brunel.ac.uk/handle/2438/10609-
dc.descriptionThis thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University Londonen_US
dc.description.abstractHeat stress and dehydration pose a severe challenge to physiological function and the capability to perform physical work. There is, however, limited knowledge on the regional haemodynamic and metabolic responses to strenuous exercise in environmentally stressful conditions. The primary aim of this thesis was to examine whether dehydration and heat stress compromise brain, muscle and systemic blood flow and metabolism, and whether depressed brain and muscle oxygen delivery underpin reduced exercise capacity during graded incremental and prolonged exercise. This thesis makes an original contribution to the knowledge by showing for the first time that dehydration markedly accelerates the decline in cerebral blood flow during maximal incremental (Chapter 4) and prolonged sub-maximal exercise (Chapter 5) in the heat. Cerebral metabolism, however, is preserved by compensatory increases in substrate extraction. Falling carbon dioxide tension underpinned the decline in CBF. However, a distinct regional distribution of blood flow across the head was observed, suggesting that different mechanisms are responsible for the regulation of regional blood flow within the head. A reduced cerebral metabolism is therefore an unlikely factor explaining the compromised exercise capacity in physiologically stressful hot environments. Rather, restrictions in active muscle blood flow and oxygen supply, which are not apparent during sub-maximal exercise, may explain the reduced maximal aerobic power in heat stressed conditions. For the first time we have manipulated skin and core temperature to show that combined internal and skin hyperthermia reduces maximal aerobic power in association with restrictions in limb, brain and systemic blood flow and skeletal muscle metabolism (Chapter 6). Overall, the findings of the present thesis provide novel information on how circulatory limitations across contracting skeletal muscle, brain and systemic tissues and organs might underpin the impairment in exercise capacity in physiologically taxing environments evoking significant dehydration and hyperthermia.en_US
dc.description.sponsorshipGatorade Sports Science Institute, PepsiCo Inc., USAen_US
dc.language.isoenen_US
dc.publisherBrunel University Londonen_US
dc.relation.urihttp://bura.brunel.ac.uk/bitstream/2438/10609/1/FulltextThesis.pdf-
dc.subjectExerciseen_US
dc.subjectCardiovascular physiologyen_US
dc.subjectCerebral blood flowen_US
dc.subjectBlood flow regulationen_US
dc.titleCirculatory limitations to exercise capacity in humans: the impact of heat stress and dehydration on brain and muscle blood flow and metabolismen_US
dc.typeThesisen_US
Appears in Collections:Dept of Life Sciences Theses
Dept of Health Sciences Theses

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