Repeat work bouts increase thermal strain for Australian firefighters working in the heat

Abstract

Background: Firefighters regularly re-enter fire scenes during long duration emergency events with limited rest between work bouts. It is unclear whether this practice is impacting on the safety of firefighters. Objectives: To evaluate the effects of multiple work bouts on firefighter physiology, strength, and cognitive performance when working in the heat. Methods: Seventy-seven urban firefighters completed two 20-minute simulated search and rescue tasks in a heat chamber (105+5u uC), separated by a 10-minute passive recovery. Core and skin temperature, rate of perceived exertion (RPE), thermal sensation (TS), grip strength, and cognitive changes between simulations were evaluated. Results: Significant increases in core temperature and perceptual responses along with declines in strength were observed following the second simulation. No differences for other measures were observed. Conclusions: A significant increase in thermal strain was observed when firefighters re-entered a hot working environment. We recommend that longer recovery periods or active cooling methods be employed prior to re-entry.

Reaction Time to Visual Stimulus in Firefighters and Healthy Trained Subjects: A Preliminary Comparative Study

“…The results showed that as the stress response increased during simulated smoke-diving, cognitive function concurrently declined. However, in contrast to these studies, previous research using experienced firefighters indicated some positive changes in visual attention following work in the heat despite no meaningful changes in processing speed or working memory [29]. It is likely that despite elevated core temperatures and fatigue levels, the relative experience of the firefighters studied by Walker et al [29] may have provided a protective mechanism against cognitive decline in the heat.…”

The effects of exercise-induced heat stress on cognitive function in firefighters

“…In their study, the cognitive task implemented took 60s to complete, and, although not specifically stated by the authors, T core may have been falling up to 0.3°C during each assessment, similar to the changes in the current study. A recent study by Walker et al (2015) reported no changes in certain aspects of cognitive function (processing speed, visual attention, and working memory) following consecutive 20-min live fire simulations separated by a 10-min passive recovery period. However, the observations by Walker et al (2015) differ from the current study possibly due to cognitive function being assessed following the second simulation, outside of the hot environment, where T core was not reported throughout the duration of the cognitive assessment and may not have continued to rise.…”

“…A recent study by Walker et al (2015) reported no changes in certain aspects of cognitive function (processing speed, visual attention, and working memory) following consecutive 20-min live fire simulations separated by a 10-min passive recovery period. However, the observations by Walker et al (2015) differ from the current study possibly due to cognitive function being assessed following the second simulation, outside of the hot environment, where T core was not reported throughout the duration of the cognitive assessment and may not have continued to rise. In addition, Hancock (1986) has also suggested that achieving heat balance, separate from the degree of T core increases, can result in restoration of cognitive function.…”

“…Cognitive function is an important factor when combating highly demanding job tasks in rapidly changing environments experienced by firefighters (Walker et al 2015). The cognitive tasks required of firefighters include assessing and executing critical decisions, situational awareness of their surroundings to determine the safest means of exiting the emergency scene (Barr et al 2010).…”

“…The cognitive tasks required of firefighters include assessing and executing critical decisions, situational awareness of their surroundings to determine the safest means of exiting the emergency scene (Barr et al 2010). The emergency environments faced by firefighters involve a dynamic environment (Walker et al 2015) in short durations that can place large demands on working memory. As previous work has focused primarily on reaction time (Smith & Petruzzello 1998), more complex tasks that are indicative of firefighting, such as sustained attention, working memory capacity, new learning, are required.…”