Psychological, physical, and heat stress indicators prior to and after a 15-minute structural firefighting task

Background: Firefighters work in strenuous conditions for prolonged periods wearing up to 20 kg of personal protective equipment. This often contributes to significant heat and cardiovascular strain. Still, little is known about how the physiological adaptations to the intense heat exposure during structural fires impact on decision-making and cognition function of firefighters. Therefore, this pilot study aimed to examine the relationships between psychological and physical measures taken prior to a 15-min structural firefighting task and the occurrence of heat stress and high levels of fatigue following the task.
Method: Nine qualified firefighters completed simulated tasks in a 15 min “live burn” scenario (130–155°C at 1.1 m above the floor), designed to mimic a fire started by a two-seater couch in a lounge room. Tympanic membrane temperature, body weight, logical reasoning, memory recall, speed and accuracy, general motivation and fatigue, and physical and mental effort were recorded pre-scenario, and at 0- and 20-minutes post-scenario. One-way repeated measures analysis of variance (ANOVA) was used to provide preliminary analysis of any changes in the measured outcomes at the three timepoints. Spearman’s correlation analyses were conducted to examine the relationships between outcomes measures recorded pre- and post-simulated fire task, including whether the participant withdrew from further assessment due to heat stress, change in tympanic membrane temperature, or score on the general motivation and fatigue scale.
Results: Two firefighters withdrew from the test due to heat stress, with age being the strongest predictor for the withdrawal (rs=−0.73, p=0.025). Findings from this study identified (a) a significant increase in the firefighter’s tympanic membrane temperature post-task (F(2,12)=192.13; p
Discussion: Preliminary results of this study suggest hydration status may be less important to operational capacity than a rise in core temperature and possibly other psychological factors. The reported weight loss (indicative of dehydration) was poorly correlated with post-task motivation and fatigue; suggesting that hydration status did not predict or impact tolerance time or cognition in strenuous conditions. Rather, fatigue was influenced more by changes in tympanic temperature than by hydration status. Firefighters with lower logical reasoning and speed and accuracy scores were more susceptible to fatigue and impaired cognition when exposed to rises in core temperature and heat stress.
Impact: Firefighters with the highest change in tympanic membrane temperature post-simulated task presented with low motivation, high fatigue, and lowest speed and accuracy test scores. This is of concern as in victim rescues, for example, firefighters may be re-entering a hazardous thermal environment fatigued and in a state of decreased cognitive capacity, impacting their decision-making and safety.
My co-authors and I acknowledge that we have no conflict of interest of relevance to the submission of the abstracts