Date of Award

4-2011

Degree Type

Thesis

Degree Name

Doctor of Philosophy

School

School of Exercise, Biomedical, and Health Sciences

Faculty

Computing, Health and Science

First Advisor

Professor Paul Laursen

Second Advisor

Professor Ken Nosaka

Third Advisor

Dr Greig Watson

Abstract

The rise in body core, skin and muscle temperatures associated with exercise
in hot environments (~30°C and above) is known to impair performance over a
variety of exercise modes and durations. Precooling has become a popular strategy to
combat this impairment, as evidence has shown it to be an effective method for
lowering pre-exercise core temperature, increasing heat storage capacity and
improving exercise performance in the heat. To date, the majority of precooling
manoeuvres are achieved via external means, such as cold water immersion and the
application of cooling garments; methods which have been criticised for their lack of
practicality for use in major sporting competitions. However, recent evidence has
shown that internal or endogenous cooling methods, such as drinking cold fluids, are
able to lower core temperature and enhance endurance performance in the heat. This
method may be more advantageous than current forms of precooling, as ingesting
cold fluids is easily implemented in the field and provides the additional benefit of
hydrating athletes. Based on the law of enthalphy of fusion, which states that a
significantly greater amount of heat absorption is required for water to change phase
from solid to liquid (melt), the ingestion of an ice slurry mixture may be a more
powerful means for lowering pre-exercise core temperature. Therefore, the primary
focus of this PhD thesis was to determine the effectiveness of ice slurry ingestion as
a precooling manoeuvre for improving submaximal exercise performance in the heat,
as well as investigate the potential mechanisms behind the improvements observed.

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