No abstract available.Thesis (DPhil)--University of Pretoria, 2011.Biokinetics, Sport and Leisure Sciencesunrestricte

Nolte, Heinrich Wilhelm

Thesis (DPhil)--University of Pretoria, 2011.No abstract available.Biokinetics, Sport and Leisure Sciencesunrestricte

UPSpace at the University of Pretoria

 Fluid, electrolyte and thermoregulatory responses to ad libitum water replacement during prolonged exercise  by  Heinrich Wilhelm Nolte  Submitted in partial fulfilment of the requirement for the degree  DOCTOR PHILOSOPHIAE (Option Biokinetics)  In the  Department of Biokinetics, Sport and Leisure Sciences  University of Pretoria                                  September 2011   © University of Pretoria   2This thesis is dedicated to my wife and best friend, Kim.                              3ACKNOWLEDGEMENTS I would like to express my sincere thanks and gratitude to the following persons and institutions for their guidance and without who’s assistance, this study would not have been possible.  Prof. Timothy Noakes: It was a privilege to work with him. His passion for South African science, expert subject knowledge and enduring support formed the cornerstone of my research.  Dr Bernard van Vuuren: For his valuable guidance, time and assistance afforded to me in the completion of this study.  ERGOTECH: For providing me with one of the most interesting jobs that one could ask for, without which this study would not have been possible.  South African National Defence Force: For providing me with the opportunity to study fluid replacement amongst South African soldiers and to contribute towards fluid replacement strategies within the SANDF. A special thanks to all the soldiers who participated during the studies.  Friends, family and colleagues: For their interest, support and encouragement throughout.  My wife: For her motivation, understanding and loving support throughout this journey. Having you to share this with made it all worth it.  The Almighty: In Him anything is possible.       4TABLE OF CONTENTS Chapter 1: General Introduction ..................................................................................................... 6 1.1 FLUID REQUIREMENTS AND REPLACEMENT STRATEGIES WITHIN A MILITARY CONTEXT .................. 7 1.2 STATEMENT OF THE PROBLEM ............................................................................................... 8 1.3 AIMS AND OBJECTIVES ......................................................................................................... 9 1.4 ABSTRACT ........................................................................................................................ 10 1.5 PUBLICATIONS................................................................................................................... 18 1.6 REFERENCES .................................................................................................................... 20 Chapter 2: Effect of ad libitum and restricted fluid replacement strategies during prolonged exercise on various hydration markers and performance of selected military tasks in soldiers........................................................................................................................................................ 22 2.1 INTRODUCTION .................................................................................................................. 23 2.2 MATERIALS AND METHODS .................................................................................................. 25 2.3 RESULTS .......................................................................................................................... 28 2.4 DISCUSSION ...................................................................................................................... 39 2.5 REFERENCES .................................................................................................................... 44 Chapter 3: Overview of assessing total body water using the diluted isotope (deuterium oxide) technique ....................................................................................................................................... 48 3.1 INTRODUCTION .................................................................................................................. 49 3.2 GENERAL OVERVIEW .......................................................................................................... 49 3.3 CORRECTIONS AND TBW CALCULATIONS ............................................................................... 51 3.4 ISOTOPE ADMINISTRATION .................................................................................................. 52 3.5 CHOICE OF PHYSIOLOGICAL FLUID AS SAMPLE MEDIUM ........................................................... 54 3.6 COLLECTION AND STORAGE OF SAMPLES .............................................................................. 54 3.7 SUMMARY OF TBW METHOD AS APPLIED DURING STUDIES PRESENTED IN CHAPTERS 4, 5 AND 6 .. 55 3.8 DEUTERIUM ABUNDANCE ANALYSIS ...................................................................................... 57 3.9 REFERENCES .................................................................................................................... 59 Chapter 4: Ad libitum fluid replacement maintains total body water, plasma osmolality and serum sodium concentrations in military personnel during a 4 hour route march .................... 63 4.1 INTRODUCTION .................................................................................................................. 64 4.2 METHODS ......................................................................................................................... 66 4.3 RESULTS .......................................................................................................................... 70 4.4 DISCUSSION ...................................................................................................................... 74 4.5 REFERENCES .................................................................................................................... 79 Chapter 5: Protection of total body water content and absence of hyperthermia despite 2% body mass loss (“voluntary dehydration”) in soldiers drinking ad libitum during prolonged exercise in cool environmental conditions .................................................................................. 86 5.1 INTRODUCTION .................................................................................................................. 87 5.2 MATERIALS AND METHODS .................................................................................................. 90 5.3 RESULTS .......................................................................................................................... 95 5.4 DISCUSSION .................................................................................................................... 102 5.5 REFERENCES .................................................................................................................. 110 Chapter 6: Appropriately trained humans can safely perform vigorous, competitive self-paced exercise in extreme heat (44°C) when drinking water ad libitum .............................................. 121 6.1 INTRODUCTION ................................................................................................................ 122 6.2 METHODS ....................................................................................................................... 124 6.3 RESULTS ........................................................................................................................ 130 6.4 DISCUSSION .................................................................................................................... 141 6.5 REFERENCES .................................................................................................................. 148      5Chapter 7: Comments on Baker et al.’s “Change in body mass accurately and reliably predicts change in body water after endurance exercise” ...................................................................... 156 7.1 BACKGROUND TO LETTER ................................................................................................. 157 7.2 LETTER TO THE EDITOR .................................................................................................... 157 7.3 REFERENCES .................................................................................................................. 167 Chapter 8: Summary, general conclusions and recommendations .......................................... 169 8.1 INTRODUCTION ................................................................................................................ 170 8.2 MAIN FINDINGS ................................................................................................................ 171 8.3 RECOMMENDATIONS FOR RESEARCH AND PRACTICE ............................................................ 176 Appendices .................................................................................................................................. 179     

Fluid, electrolyte and thermoregulatory responses to ad libitum water replacement during prolonged exercise

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Fluid, electrolyte and thermoregulatory responses to ad libitum water replacement during prolonged exercise

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