The effects of combined creatine and glycerol hyperhydration on thermoregulation, metabolism and exercise performance in the heat in endurance trained humans
The primary objective of these series of experiments was to develop an optimal hyperhydration strategy for use during conditions of restricted water access or exercise-induced heat stress. This strategy was composed of two compounds, namely Cr and Gly which each targeted specific body water compartments in order to maximise the volume of retained water. Endurance-trained subjects were recruited to participate in the current series of three experiments, and following Cr/Gly supplementation, body water was estimated by multifrequency bioimpedance and the physiological responses to exercise in the heat (30°C, 70% relative humidity) recorded and compared to pre-supplementation values. The aim of the first study presented in this thesis (Chapter 3(a)) was to examine the effects of combined Cr and Gly supplementation on fluid retention and subsequently the effects on cardiovascular, thermoregulatory and metabolic responses and performance during exercise in the heat. The aim of Chapter 3 (b) was to examine the effects of a novel method of Cr and Gly delivery and ingestion on fluid retention and distribution. Chapter 4 (a) aimed to assess the effects of Cr and Gly supplementation ingested according to the loading protocol described in the previous chapter (6 days of Cr and Gly ingestion, with the final supplement consumed 3 hours prior to measurement) on cardiovascular, thermoregulatory and metabolic responses and performance during exercise in the heat. The aim of the study in Chapter 4 (b) was to examine the effects of extending the period of time between ingestion of the final Cr/Gly supplement on the retention and distribution of fluid. The experiment in chapter 5 compared the effects of the novel Cr and Gly loading protocol established in Chapter 4 (b) on cardiovascular, thermoregulatory and metabolic responses and performance during exercise in the heat. The aim of Chapter 6 was to compare Tc measurements obtained using an ingestible telemetry pill and a tympanic membrane thermometer with those from a rectal thermistor during rest and high intensity exercise conducted in a hot and humid environment (30°C and 70% relative humidity) intended to raise Tc above 39°C.