larsen-multipledaysof-2015.pdf (646.32 kB)
Multiple days of heat exposure on firefighters' work performance and physiology
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posted on 2015-01-01, 00:00 authored by Brianna Larsen, Rod SnowRod Snow, Grace Vincent, Jacqueline Tran, Alex Wolkow, Brad AisbettBrad AisbettThis 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).
History
Journal
PLoS OneVolume
10Issue
9Season
Article Number : e0136413Article number
e0136413Pagination
1 - 16Publisher
Public Library of Science (PLOS)Location
San Francisco, Calif.Publisher DOI
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eISSN
1932-6203Language
engPublication classification
C Journal article; C1 Refereed article in a scholarly journalCopyright notice
2015, The AuthorsUsage metrics
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