Multiple days of heat exposure on firefighters’ work performance and physiology

Larsen, Brianna and Snow, Rod and Vincent, Grace and Tran, Jacqueline and Wolkow, Alexander and Aisbett, Brad (2015) Multiple days of heat exposure on firefighters’ work performance and physiology. PLoS One, 10 (9):e0136413. pp. 1-16.

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Abstract

This study assessed the accumulated effect of ambient heat on the performance of, and physiological and perceptual responses to, intermittent, simulated wildfire fighting tasks over three consecutive days. Firefighters (n = 36) were matched and allocated to either the CON (19°C) or HOT (33°C) condition. They performed three days of intermittent, self-paced simulated firefighting work, interspersed with physiological testing. Task repetitions were counted (and converted to distance or area) to determine work performance. Participants were asked to rate their perceived exertion and thermal sensation after each task. Heart rate, core temperature (Tc), and skin temperature (Tsk) were recorded continuously throughout the simulation. Fluids were consumed ad libitum. Urine volume was measured throughout, and urine specific gravity (USG) analysed, to estimate hydration. All food and fluid consumption was recorded. There was no difference in work output between experimental conditions. However, significant variation in performance responses between individuals was observed. All measures of thermal stress were elevated in the HOT, with core and skin temperature reaching, on average, 0.24 ± 0.08°C and 2.81 ± 0.20°C higher than the CON group. Participants’ doubled their fluid intake in the HOT condition, and this was reflected in the USG scores, where the HOT participants reported significantly lower values. Heart rate was comparable between conditions at nearly all time points, however the peak heart rate reached each circuit was 7 ± 3% higher in the CON trial. Likewise, RPE was slightly elevated in the CON trial for the majority of tasks. Participants’ work output was comparable between the CON and HOT conditions, however the performance change over time varied significantly between individuals. It is likely that the increased fluid replacement in the heat, in concert with frequent rest breaks and task rotation, assisted with the regulation of physiological responses (e.g., heart rate, core temperature).


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Copyright: © 2015 Larsen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 20 Sep 2020 23:47
Last Modified: 21 Sep 2020 00:14
Uncontrolled Keywords: longitudinal data; project aquarius; exercise; stress; models; temperature; ingestion; exertion; bushfire; caffeine
Fields of Research (2008): 11 Medical and Health Sciences > 1106 Human Movement and Sports Science > 110602 Exercise Physiology
11 Medical and Health Sciences > 1117 Public Health and Health Services > 111705 Environmental and Occupational Health and Safety
Socio-Economic Objectives (2008): C Society > 92 Health > 9205 Specific Population Health (excl. Indigenous Health) > 920505 Occupational Health
Identification Number or DOI: 10.1371/journal.pone.0136413
URI: http://eprints.usq.edu.au/id/eprint/39607

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