IntroductiondWildland firefighters (WLFF) work long hours in extreme environments, resulting in high daily total energy expenditure. Increasing work-shift eating episodes and/or providing rations that promote convenient eating has shown augmented self-selected work output, as has regular carbohydrate (CHO) consumption. It remains unclear how current WLFF feeding strategies compare to more frequent nutrient delivery. Our aim was to determine WLFFs' self-selected field total energy intake (TEI), composition, and feeding patterns during wildland fire suppression shifts. MethodsdWLFF were deployed to fire incidents across the United States throughout the 2018 fire season. Preshift food inventories collected at basecamp provided item-specific nutrient content (kilocalories, CHO, fat, protein). Work shift consumption (TEI, feeding frequency, episodic composition) was monitored in real time by field researchers on fireline via observational data capture using mobile tablets. Shift work output was also quantified via actigraph accelerometry. ResultsdEighty-six WLFF (27.5±6.4 y; 16 female, 70 male) worked 14.0±1.1 h shifts, with a TEI of 6.3±2.5 MJ (1494±592 kcal) (51±10, 37±9, 13±4% for CHO, fat, and protein, respectively). WLFF averaged 4.3±1.6 eating episodes (1.4±1.3 MJ [345±306 kcal] and 44±38 g CHO$episode-1). WLFF who consumed >20 kcal$kg-1 averaged less sedentary activity than those consuming <16 kcal$kg-1. Data are presented as mean±SD. ConclusionsdNot including fire camp meals (breakfast, dinner), the present work-shift TEI approximates 33% of previously determined WLFF total energy expenditure and demonstrates that current WLFF consumption patterns may not deliver adequate nutrients for occupational demands.
ObjectivesIn order to make recommendations to protect wildland firefighters (WLFFs) from heat-related illness, the role physical exertion plays on core body temperature (Tc) in the work environment needs to be considered. We aimed to estimate the association of time-varying job tasks with differing exertion levels on change in Tc, among WLFFs engaged in fire management activities, while controlling for ambient conditions and individual characteristics. In addition, we examined whether duration of tasks modified the relationship between task and change in Tc.MethodsWe used data from The Wildland Firefighter Heat Related Illness study, a repeated measures study with individual-level data on 301 WLFFs from 2013 to 2016. Job tasks over one full shift were recorded and categorised into four levels (sedentary, light, moderate and high) based on estimated exertion levels. Tc was measured every 15 s using an ingestible sensor and personal monitors measured ambient conditions. The analysis used generalised estimating equations with an autoregressive correlation structure.ResultsWe found statistically significant associations between job tasks with increased physical demand and increases in Tc. When compared with sedentary tasks, the estimated increases in Tc for light, moderate and high activity tasks of average duration were 0.07°C (95% CI 0.02 to 0.11°C), 0.19°C (95% CI 0.15 to 0.23) and 0.44°C (95% CI 0.39 to 0.49°C), respectively. In addition, we found evidence of interaction between task type and duration.ConclusionsThis study supports the hypothesis that occupational exposure to physical exertion increases Tc, highlighting the need to update recommendations to protect WLFFs from heat-related illness.
Introduction-The purpose of this study was to evaluate heat stress occurring in wildfire management activities with variable environmental conditions.Methods-Direct observation and real-time wireless physiological monitoring allowed for weather and physiological metrics, including heart rate, core temperature (T c ), skin temperature, and physiological strain index (PSI), of male (n=193) and female (n=28) wildland firefighters (WLFFs) to be recorded during wildfire management activities. Accelerometry data were used to categorize intensity level of activity.Results-Ambient temperature and relative humidity values were used to compute the heat index (HI; n=3891 h) and divided into quartiles (Q1: 13.3e25.1 • C; Q2: 25.2e26.4 • C; Q3: 26.5e28.9 • C; Q4: 29.0e49.1 • C). Activity levels remained relatively constant across all HI quartiles. The percentage of time spent performing moderate/vigorous activities was lowest during the hotter Q4 (Q1: 3%; Q2: 2%; Q3: 2%; Q4: 1%). Heart rate, T c , PSI, and skin temperature associations with HI varied by resource type. Sixty-one percent of WLFFs (n=134) experienced a T c ≥38.0 • C, and 50% of WLFFs (n=111) experienced a PSI ≥6.0.Conclusions-Heat stress was prevalent as WLFFs performed job tasks of varying intensities in all ambient conditions. Spontaneous bouts of arduous labor, duration of work shifts, and other occupation characteristics present the possibility for substantial durations of hyperthermia, although no heat-related injuries occurred in this study. Despite chronic exposure to rugged sloped terrain, load carriage, and environmental conditions, self-regulation and individual attention to managing work:rest appears to be the primary management strategy in mitigating excessive accumulation of body heat in this occupation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.