Materials and Methods
Participants
Male and female volunteer and career firefighters (n = 36) participated in this study (~14%
female, in accordance with the ratios observed within Australia’s firefighting population [15]).
Participants in each group were matched (in order of priority) by age, gender, and body mass
index [16] in order to minimise variation between groups. Participants were also matched
according to the sequence in which they completed the physical work circuit (see Experimental
Protocol for details). A self-report measure of habitual physical activity was also collected from
each participant in order to glean an indication of their aerobic fitness levels, given this is a factor
known to influence exercise performance in the heat. Unfortunately direct measures of aerobic
fitness were unable to be conducted due to time and cost constraints. Firefighters from
hotter climates (e.g., Northern Australia) were excluded from the study in order to control a
potentially confounding variable (heat acclimation), and reduce variation in the participant
cohort. Data collection also took place during the autumn and winter months to minimise the
effect of heat acclimation. Participants provided written informed consent and filled out a
Medical Questionnaire prior to commencement of the study to ensure they were physically
able to perform the work protocol. Ethical approval was obtained for this study by Deakin University
(DUHREC 2014–040).