Loughborough University
Leicestershire, UK
LE11 3TU
+44 (0)1509 263171
Loughborough University

Loughborough University Institutional Repository

Please use this identifier to cite or link to this item: https://dspace.lboro.ac.uk/2134/10108

Title: Examining hydration status and the physiological and behavioural influences on voluntary water intake
Authors: Mears, Stephen A.
Keywords: Voluntary water intake
Hydration status
High intensity
Work place
Issue Date: 2012
Publisher: © Stephen A Mears
Abstract: Understanding the physiological and behavioural reasons that result in voluntary water intake and the volume subsequently consumed in both the work place and during and following an exercise setting can provide further information on water balance and the necessity and requirements of water intake. The first study (Chapter 3) aimed to assess hydration status in the adult population at the start and end of a working day and the amount of water from beverages that was consumed. Urine osmolality and urine specific gravity (USG) suggested a large proportion of subjects arrived (osmolality: 54%; USG: 53%) and left (osmolality: 35%; USG: 33%) work in a hypohydrated state, with variation between subjects in the same and different places of work. Reported water intake varied between groups with males consuming more than females. To further examine hydration status it was proposed to assess the use of capillary blood sampling as an alternative to more restrictive venous blood sampling (Chapter 4), however, despite tracking changes in blood parameters in a similar capacity, the inconsistencies of results suggested capillary blood sampling could not be used reliably. The remaining chapters in the thesis examined voluntary water intake. In Chapter 5 this was during and following exercise in the cold. Less water was consumed compared to exercise in a warm environment and there was an indication of a blunted thirst response in the cold. Following high intensity intermittent exercise, more water was voluntarily consumed during a one hour recovery period compared to when continuous exercise of the same average power output was performed (Chapter 6). Following exercise there was increased serum osmolality, serum sodium concentration, plasma vasopressin concentration and blood lactate concentration compared to baseline values. The relative contribution that decreasing blood lactate concentrations and water intake during the recovery period had on serum osmolality could not be determined, so the study in Chapter 7 was carried out. The time period during which voluntary water intake was allowed was manipulated during a recovery period following a period of high intensity intermittent exercise. Allowing water intake for the full hour, the final 30 minutes or not at all, resulted in similar decreases in serum osmolality throughout the duration of the recovery period. A combination of finishing the period of exercise allowing plasma volume restoration, reduction in blood lactate concentration, reduction in serum sodium concentration, a restoration of blood lactate concentration and water intake appeared to contribute to decreased serum osmolality. Sensations of thirst were the main stimulants of voluntary water intake (Chapters 3, 5, 6 and 7), however, following exercise, sensations of thirst resulted in water consumption despite the majority of subjects not losing enough water (>2% body mass loss) to require additional rehydration. In this thesis, it can be concluded that voluntary water intake differs between individuals, between work environments, during and following exercise in different environments and following different exercise intensities. Water intake is generally initiated by sensations of thirst arising from physiological and behavioural mechanisms even in the absence of significant hypohydration and will reduce once satiated.
Description: A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.
URI: https://dspace.lboro.ac.uk/2134/10108
Appears in Collections:PhD Theses (Sport, Exercise and Health Sciences)

Files associated with this item:

File Description SizeFormat
Thesis-2012-Mears.pdf1.65 MBAdobe PDFView/Open
Form-2012-Mears.pdf1.42 MBAdobe PDFView/Open


SFX Query

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.