The Effects of Simulated Wildland Firefighting Tasks on Core Temperature and Cognitive Function under Very Hot Conditions.

F Michael Williams-Bell,Bernadette A Murphy,Brad Aisbett,Brianna Larsen

doi:10.3389/fphys.2017.00815

F Michael Williams-Bell, Bernadette A Murphy + Show 2 more

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https://doi.org/10.3389/fphys.2017.00815

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Abstract

Background: The severity of wildland fires is increasing due to continually hotter and drier summers. Firefighters are required to make life altering decisions on the fireground, which requires analytical thinking, problem solving, and situational awareness. This study aimed to determine the effects of very hot (45°C; HOT) conditions on cognitive function following periods of simulated wildfire suppression work when compared to a temperate environment (18°C; CON).Methods: Ten male volunteer firefighters intermittently performed a simulated fireground task for 3 h in both the CON and HOT environments, with cognitive function tests (paired associates learning and spatial span) assessed at baseline (cog 1) and during the final 20-min of each hour (cog 2, 3, and 4). Reaction time was also assessed at cog 1 and cog 4. Pre- and post- body mass were recorded, and core and skin temperature were measured continuously throughout the protocol.Results: There were no differences between the CON and HOT trials for any of the cognitive assessments, regardless of complexity. While core temperature reached 38.7°C in the HOT (compared to only 37.5°C in the CON; p < 0.01), core temperature declined during the cognitive assessments in both conditions (at a rate of −0.15 ± 0.20°C·hr−1 and −0.63 ± 0.12°C·hr−1 in the HOT and CON trial respectively). Firefighters also maintained their pre-exercise body mass in both conditions, indicating euhydration.Conclusions: It is likely that this maintenance of euhydration and the relative drop in core temperature experienced between physical work bouts was responsible for the preservation of firefighters' cognitive function in the present study.

Highlights

Wildland fires destroy vast amounts of land on a global scale (Liu et al, 2010) and represent a significant financial burden for both individuals and government (Hyde et al, 2007)
With increased fire severity comes increased demands placed on wildland firefighters, which may exacerbate the risks already associated with the occupation (Aisbett et al, 2012)
There were no differences in mass (PRE: 89.2 ± 2.8 kg vs. 89.2 ± 2.8 kg; POST: 89.1 ± 2.8 kg vs. 89.7 ± 2.8 kg), body mass index (BMI; 27.5 ± 1.0 kg.m−2 vs. 27.5 ± 1.0 kg.m−2), or percent change in body mass (−0.1 ± 0.3% vs. 0.5 ± 0.3%) for the CON and HOT trials, respectively (p > 0.05)

Summary

Introduction

Wildland fires destroy vast amounts of land on a global scale (Liu et al, 2010) and represent a significant financial burden for both individuals and government (Hyde et al, 2007) Such fire events are becoming more severe (Hennessy and Wales, 2005), likely due to the increasingly hot and dry summers experienced as a result of climate change (Westerling et al, 2006) as well as continued. Firefighters performing occupational operations are required to wear thermal protective clothing (TPC) that can impair normal thermoregulation (Morley et al, 2012) This impairment could induce hypohydration and hyperthermia, both of which can negatively impact cognitive function (Morley et al, 2012). This study aimed to determine the effects of very hot (45◦C; HOT) conditions on cognitive function following periods of simulated wildfire suppression work when compared to a temperate environment (18◦C; CON)

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