Comprehensive Physiology Wiley Online Library
For Librarians For Authors Editors About

Physiology of the Wildland Firefighter: Managing Extreme Energy Demands in Hostile, Smoky, Mountainous Environments

Brent C. Ruby, Robert H. Coker, Joe Sol, John Quindry, Scott J. Montain

10.1002/cphy.c220016

Source: Volume 13, Issue 2, April 2023

Published online: March 2023

Full Article on Wiley Online Library



Abstract

Wildland firefighters (WLFFs) are inserted as the front‐line defense to minimize loss of natural resources, property, and human life when fires erupt in forested regions of the world. The WLFF occupation is physically demanding as exemplified by total daily energy expenditures that can exceed 25 MJ/day (6000 calories). WLFFs must also cope with complex physical and environmental situations (i.e., heat, altitude, smoke, compromised sleep, elevated stress) which challenge thermoregulatory responses, impair recovery, and increase short‐ and long‐term injury/health risks while presenting logistical obstacles to nutrient and fluid replenishment. The occupation also imposes emotional strain on both the firefighter and their families. The long‐term implications of wildfire management and suppression on the physical and mental health of WLFFs are significant, as the frequency and intensity of wildland fire outbreaks as well as the duration of the fire season is lengthening and expected to continue to expand over the next three decades. This article details the physical demands and emerging health concerns facing WLFFs, in addition to the challenges that the U.S. Forest Service and other international agencies must address to protect the health and performance of WLFFs and their ability to endure the strain of an increasingly dangerous work environment. © 2023 American Physiological Society. Compr Physiol 13:4587‐4615, 2023.

Figure 1. Figure 1. Expected metabolic load variability during wildfire management (simulated and live activities) and training/conditioning. Data collection during simulated fireline observation via indirect calorimetry 14. GPS derived estimated metabolic load during live fireline assignments and training 120. Measures of Tvent prior to and following the season 47. Simulated escape from Ruby et al. 107.
Figure 2. Figure 2. Theoretical model that depicts the implications of shift operations, the energy expenditure of physical activity (EEA), and nutrient intake on expected glycogen depletion and recovery (dotted line). Anticipated values of daily EEA are represented (800–3500 kcal/24 h) in red across the varied phases of an extended assignment. The campfire graphic represents the intensity of the wildfire assignment. Postshift CHO access is represented by lower levels of intake (<<) and higher levels of intake (>). The average expected energy expenditure of activity (EEA) is represented as less than average EED (<) or higher than the average EEA on assignments (>>>). The expected range of EEA values is derived from prior work 40,109. The expected range of muscle glycogen values is derived from prior samples on the fireline 39.
Figure 3. Figure 3. Timeline of a heat‐related injury during arduous wildland fire management with the individual drinking behavior prior to presenting with heat injury and their body core temperature over time. Adapted, with permission, from Cuddy JS and Ruby BC, 2011 37.
Figure 4. Figure 4. Theoretical concepts surrounding the occupational factors of wildland fire management that influence deconditioning, pollutant exposure, and chronic stress triad (DPST) and potential countermeasures that may reduce seasonal health in wildland firefighters. PM2.5, fine particulate matter.
Figure 5. Figure 5. Physical characteristics of male and wildland firefighters on assignment and a comprehensive description of the measured energy demands, fluid budgets, nutrient intake, work shift characteristics (length, equipment, cardiovascular, and thermal loads), and seasonal responses and their relationship to the Standard Fire Orders 4.


Figure 1. Expected metabolic load variability during wildfire management (simulated and live activities) and training/conditioning. Data collection during simulated fireline observation via indirect calorimetry 14. GPS derived estimated metabolic load during live fireline assignments and training 120. Measures of Tvent prior to and following the season 47. Simulated escape from Ruby et al. 107.


Figure 2. Theoretical model that depicts the implications of shift operations, the energy expenditure of physical activity (EEA), and nutrient intake on expected glycogen depletion and recovery (dotted line). Anticipated values of daily EEA are represented (800–3500 kcal/24 h) in red across the varied phases of an extended assignment. The campfire graphic represents the intensity of the wildfire assignment. Postshift CHO access is represented by lower levels of intake (<<) and higher levels of intake (>). The average expected energy expenditure of activity (EEA) is represented as less than average EED (<) or higher than the average EEA on assignments (>>>). The expected range of EEA values is derived from prior work 40,109. The expected range of muscle glycogen values is derived from prior samples on the fireline 39.


Figure 3. Timeline of a heat‐related injury during arduous wildland fire management with the individual drinking behavior prior to presenting with heat injury and their body core temperature over time. Adapted, with permission, from Cuddy JS and Ruby BC, 2011 37.


Figure 4. Theoretical concepts surrounding the occupational factors of wildland fire management that influence deconditioning, pollutant exposure, and chronic stress triad (DPST) and potential countermeasures that may reduce seasonal health in wildland firefighters. PM2.5, fine particulate matter.


Figure 5. Physical characteristics of male and wildland firefighters on assignment and a comprehensive description of the measured energy demands, fluid budgets, nutrient intake, work shift characteristics (length, equipment, cardiovascular, and thermal loads), and seasonal responses and their relationship to the Standard Fire Orders 4.
References
 1.ACIA. Impacts of a Warming Arctic: Arctic Climate Impact Assessment, 2004.
 2.Adetona O, Reinhardt TE, Domitrovich J, Broyles G, Adetona AM, Kleinman MT, Ottmar RD, Naeher LP. Review of the health effects of wildland fire smoke on wildland firefighters and the public. Inhal Toxicol 28: 95‐139, 2016.
 3.Adetona O, Simpson CD, Onstad G, Naeher LP. Exposure of wildland firefighters to carbon monoxide, fine particles, and levoglucosan. Ann Occup Hyg 57: 979‐991, 2013.
 4.Agriculture Do. Interagency Standards for Fire and Fire Aviation Operations. Boise, ID: Interagency Fire Center, 2022.
 5.Aisbett B, Wolkow A, Sprajcer M, Ferguson SA. “Awake, smoky, and hot”: Providing an evidence‐base for managing the risks associated with occupational stressors encountered by wildland firefighters. Appl Ergon 43: 916‐925, 2012.
 6.Albini FA. Response of free‐burning fires to nonsteady wind. Combust Sci Technol 29: 225‐241, 1982.
 7.Amster ED, Fertig SS, Baharal U, Linn S, Green MS, Lencovsky Z, Carel RS. Occupational exposures and symptoms among firefighters and police during the carmel forest fire: The Carmel cohort study. Isr Med Assoc J 15: 288‐292, 2013.
 8.Andrzej Bytnerowicz MA, Andersen C, Riebau A(Ed.). Wildland Fires and Air Pollution. Developments in Environmental Science 8. Amsterdam, The Netherlands: US Department of Agriculture, 2009.
 9.Booth FW, Roberts CK, Laye MJ. Lack of exercise is a major cause of chronic diseases. Compr Physiol 2: 1143‐1211, 2012.
 10.Bosch AN, Noakes TD. Carbohydrate ingestion during exercise and endurance performance. Indian J Med Res 121: 634‐638, 2005.
 11.Brook RD, Rajagopalan S, Pope CA 3rd, Brook JR, Bhatnagar A, Diez‐Roux AV, Holguin F, Hong Y, Luepker RV, Mittleman MA, Peters A, Siscovick D, Smith SC Jr, Whitsel L, Kaufman JD. Particulate matter air pollution and cardiovascular disease: An update to the scientific statement from the American Heart Association. Circulation 121: 2331‐2378, 2010.
 12.Brooks SJ, West MR, Domitrovich JW, Sol JA, Holubetz H, Partridge C, Ruby BC, Brown AF, Roe AJ. Nutrient intake of wildland firefighters during arduous wildfire suppression: Macronutrient and micronutrient consumption. J Occup Environ Med 63: e949‐e956, 2021.
 13.Brown TJ, Hall BL, Westerling AL. The impact of twenty‐first century climate change on wildland fire danger in the Western United States: An applications perspective. Clim Chang 62: 365‐388, 2004.
 14.Budd GBJ, Hendrie A, Jeffery S, Beasley F, Costin B, Zhien W, Baker M, Cheney N, Dawson M. Project aquarius 1. Stress, strain, and productivity in men suppressing Australian summer bushfires with hand tools: Background, objectives, and methods. Int J Wildland Fire 7: 69‐76, 1997.
 15.Budd GM. How do wildland firefighters cope? Physiological and behavioural temperature regulation in men suppressing Australian summer bushfires with hand tools. J Therm Biol 26: 381‐386, 2001.
 16.Burke LM, Cox GR, Culmmings NK, Desbrow B. Guidelines for daily carbohydrate intake: Do athletes achieve them? Sports Med 31: 267‐299, 2001.
 17.Burke LM, van Loon LJC, Hawley JA. Postexercise muscle glycogen resynthesis in humans. J Appl Physiol 122: 1055‐1067, 2017.
 18.Carmen ED, Saladino C, Brown WE. Urban and suburban population growth in the mountain west. 2019.
 19.Carmona‐Moreno C, Belward A, Malingreau J‐P, Hartley A, Garcia‐Alegre M, Antonovskiy M, Buchshtaber V, Pivovarov V. Characterizing interannual variations in global fire calendar using data from earth observing satellites. Glob Chang Biol 11: 1537‐1555, 2005.
 20.Cascio WE. Wildland fire smoke and human health. Sci Total Environ 624: 586‐595, 2018.
 21.Cater H, Clancy D, Duffy K, Holgate A, Wilison B, Wood J. Fatigue on the fireground: The DPI experience. In: Australasian Fire Authorities Council/Bushfire Co‐Operative Research Centre Annual Conference. Hobart, Australia, 2007.
 22.Chen H, Samet JM, Bromberg PA, Tong H. Cardiovascular health impacts of wildfire smoke exposure. Part Fibre Toxicol 18: 2, 2021.
 23.Cherry N, Galarneau JM, Kinniburgh D, Quemerais B, Tiu S, Zhang X. Exposure and absorption of PAHs in wildland firefighters: A field study with pilot interventions. Ann Work Expo Health 65: 148‐161, 2021.
 24.Cheung SS, McLellan TM, Tenaglia S. The thermophysiology of uncompensable heat stress. Physiological manipulations and individual characteristics. Sports Med 29: 329‐359, 2000.
 25.Christison KS, Gurney SC, Sol JA, Williamson‐Reisdorph CM, Quindry TS, Quindry JC, Dumke CL. Muscle damage and overreaching during wildland firefighter critical training. J Occup Environ Med 63: 350‐356, 2021.
 26.Cochrane MA. Fire science for rainforests. Nature 421: 913‐919, 2003.
 27.Coker MS, Ladd K, Murphy CJ, Ruby BC, Shriver TC, Schoeller DA, Newcomer BR, Bateman T, Bartlett L, Coker RH. Alaska backcountry expeditionary hunting promotes rapid improvements in metabolic biomarkers in healthy males and females. Physiol Rep 9: e14682, 2021.
 28.Coker RH, Coker MS, Bartlett L, Murphy CJ, Priebe K, Shriver TC, Schoeller DA, Ruby BC. The energy requirements and metabolic benefits of wilderness hunting in Alaska. Physiol Rep 6: e13925, 2018.
 29.Coker RH, Murphy CJ, Johannsen M, Galvin G, Ruby BC. Wildland firefighting: Adverse influence on indices of metabolic and cardiovascular health. J Occup Environ Med 61: e91‐e94, 2019.
 30.Cooper JA, Nguyen DD, Ruby BC, Schoeller DA. Maximal sustained levels of energy expenditure in humans during exercise. Med Sci Sports Exerc 43: 2359‐2367, 2011.
 31.Coyle EF. Fluid and fuel intake during exercise. J Sports Sci 22: 39‐55, 2004.
 32.Cramer MJ, Dumke CL, Hailes WS, Cuddy JS, Ruby BC. Postexercise glycogen recovery and exercise performance is not significantly different between fast food and sport supplements. Int J Sport Nutr Exerc Metab 25: 448‐455, 2015.
 33.Cuddy JS, Buller M, Hailes WS, Ruby BC. Skin temperature and heart rate can be used to estimate physiological strain during exercise in the heat in a cohort of fit and unfit males. Mil Med 178: e841‐e847, 2013.
 34.Cuddy JS, Gaskill SE, Sharkey BJ, Harger SG, Ruby BC. Supplemental feedings increase self‐selected work output during wildfire suppression. Med Sci Sports Exerc 39: 1004‐1012, 2007.
 35.Cuddy JS, Ham JA, Harger SG, Slivka DR, Ruby BC. Effects of an electrolyte additive on hydration and drinking behavior during wildfire suppression. Wilderness Environ Med 19: 172‐180, 2008.
 36.Cuddy JS, Reinert AR, Hansen KC, Ruby BC. Effects of modafinil and sleep loss on physiological parameters. Mil Med 173: 1092‐1097, 2008.
 37.Cuddy JS, Ruby BC. High work output combined with high ambient temperatures caused heat exhaustion in a wildland firefighter despite high fluid intake. Wilderness Environ Med 22: 122‐125, 2011.
 38.Cuddy JS, Slivka DR, Hailes WS, Dumke CL, Ruby BC. Metabolic profile of the Ironman World Championships: A case study. Int J Sports Physiol Perform 5: 570‐576, 2010.
 39.Cuddy JS, Slivka DR, Tucker TJ, Hailes WS, Ruby BC. Glycogen levels in wildland firefighters during wildfire suppression. Wilderness Environ Med 22: 23‐27, 2011.
 40.Cuddy JS, Sol JA, Hailes WS, Ruby BC. Work patterns dictate energy demands and thermal strain during wildland firefighting. Wilderness Environ Med 26: 221‐226, 2015.
 41.DeLany JP, Schoeller DA, Hoyt RW, Askew EW, Sharp MA. Field use of D2 18O to measure energy expenditure of soldiers at different energy intakes. J Appl Physiol (1985) 67: 1922‐1929, 1989.
 42.De‐Lorenzo‐Green T, Sharkey B. Development and validation of a work capacity test for wildland firefighters: 930. Med Sci Sports Exerc 27: S166, 1995.
 43.Epton MJ, Dawson RD, Brooks WM, Kingham S, Aberkane T, Cavanagh JA, Frampton CM, Hewitt T, Cook JM, McLeod S, McCartin F, Trought K, Brown L. The effect of ambient air pollution on respiratory health of school children: A panel study. Environ Health 7: 16, 2008.
 44.Ferguson MD, Semmens EO, Dumke C, Quindry JC, Ward TJ. Measured pulmonary and systemic markers of inflammation and oxidative stress following wildland firefighter simulations. J Occup Environ Med 58: 407‐413, 2016.
 45.Flynn S, Rosales A, Hailes W, Ruby B. Males and females exhibit similar muscle glycogen recovery with varied recovery food sources. Eur J Appl Physiol 120: 1131‐1142, 2020.
 46.Foster E, Lee C, Imamura F, Hollidge SE, Westgate KL, Venables MC, Poliakov I, Rowland MK, Osadchiy T, Bradley JC, Simpson EL, Adamson AJ, Olivier P, Wareham N, Forouhi NG, Brage S. Validity and reliability of an online self‐report 24‐h dietary recall method (Intake24): A doubly labelled water study and repeated‐measures analysis. J Nutr Sci 8: e29, 2019.
 47.Gaskill SE, Dumke CL, Palmer CG, Ruby BC, Domitrovich JW, Sol JA. Seasonal changes in wildland firefighter fitness and body composition. Int J Wildland Fire 29: 294‐303, 2020.
 48.Gumieniak RJ, Gledhill N, Jamnik VK. Physical employment standard for Canadian wildland firefighters: Examining test‐retest reliability and the impact of familiarisation and physical fitness training. Ergonomics 61: 1324‐1333, 2018.
 49.Gurney SC, Christison KS, Stenersen T, Dumke CL. Effect of uncompensable heat from the wildland firefighter helmet. Int J Wildland Fire 30: 990‐997, 2021.
 50.Harris JA, Benedict FG. A biometric study of human basal metabolism. Proc Natl Acad Sci U S A 4: 370‐373, 1918.
 51.Heil DP. Estimating energy expenditure in wildland fire fighters using a physical activity monitor. Appl Ergon 33: 405‐413, 2002.
 52.Heinrich EC, Djokic MA, Gilbertson D, DeYoung PN, Bosompra NO, Wu L, Anza‐Ramirez C, Orr JE, Powell FL, Malhotra A, Simonson TS. Cognitive function and mood at high altitude following acclimatization and use of supplemental oxygen and adaptive servoventilation sleep treatments. PLoS One 14: e0217089, 2019.
 53.Hendrie AL, Brotherhood JR, Budd GR, Jeffery SE, Beasley F, Costin BP, Zhien W, Baker M, Cheney NP, Dawson M. Project aquarius 8. Sweating, drinking, and dehydration in men suppressing wildland fires. Int J Wildland Fire 7: 145‐158, 1997.
 54.Hess H, Hostler D. Respiratory muscle training effects on performance in hypo‐ and hyperbaria. Aerosp Med Hum Perform 89: 996‐1001, 2018.
 55.Hew‐Butler T, Rosner MH, Fowkes‐Godek S, Dugas JP, Hoffman MD, Lewis DP, Maughan RJ, Miller KC, Montain SJ, Rehrer NJ, Roberts WO, Rogers IR, Siegel AJ, Stuempfle KJ, Winger JM, Verbalis JG. Statement of the Third International Exercise‐Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clin J Sport Med 25: 303‐320, 2015.
 56.Hew‐Butler TD, Sharwood K, Collins M, Speedy D, Noakes T. Sodium supplementation is not required to maintain serum sodium concentrations during an Ironman triathlon. Br J Sports Med 40: 255‐259, 2006.
 57.Hing M, Cabrera J, Barstow C, Forsten R. Special operations forces and incidence of post‐traumatic stress disorder symptoms. J Spec Oper Med 12: 23‐35, 2012.
 58.Houck JM, Mermier CM, Beltz NM, Johnson KE, VanDusseldorp TA, Escobar KA, Gibson AL. Physical fitness evaluation of career urban and wildland firefighters. J Occup Environ Med 62: e302‐e307, 2020.
 59.Hoyt RW, Jones TE, Baker‐Fulco CJ, Schoeller DA, Schoene RB, Schwartz RS, Askew EW, Cymerman A. Doubly labeled water measurement of human energy expenditure during exercise at high altitude. Am J Phys 266: R966‐R971, 1994.
 60.Innes JM, Clarke A. The responses of professional fire‐fighters to disaster. Disasters 9: 149‐154, 1985.
 61.Jeukendrup AE. Carbohydrate intake during exercise and performance. Nutrition 20: 669‐677, 2004.
 62.Jongeneelen FJ, Bos RP. Excretion of pyrene and hydroxypyrene in urine. Cancer Lett 51: 175‐179, 1990.
 63.Kubesch NJ, de Nazelle A, Westerdahl D, Martinez D, Carrasco‐Turigas G, Bouso L, Guerra S, Nieuwenhuijsen MJ. Respiratory and inflammatory responses to short‐term exposure to traffic‐related air pollution with and without moderate physical activity. Occup Environ Med 72: 284‐293, 2015.
 64.Lane HW, Gretebeck RJ, Schoeller DA, Davis‐Street J, Socki RA, Gibson EK. Comparison of ground‐based and space flight energy expenditure and water turnover in middle‐aged healthy male US astronauts. Am J Clin Nutr 65: 4‐12, 1997.
 65.Larsen B, Snow R, Aisbett B. Effect of heat on firefighters' work performance and physiology. J Therm Biol 53: 1‐8, 2015.
 66.Larsen B, Snow R, Vincent G, Tran J, Wolkow A, Aisbett B. Multiple days of heat exposure on firefighters' work performance and physiology. PLoS One 10: e0136413, 2015.
 67.Larsen B, Snow R, Williams‐Bell M, Aisbett B. Simulated firefighting task performance and physiology under very hot conditions. Front Physiol 6: 322, 2015.
 68.Leykin D, Lahad M, Bonneh N. Posttraumatic symptoms and posttraumatic growth of israeli firefighters, at one month following the carmel fire disaster. Psychiatry J 2013: 274121, 2013.
 69.Lieberman HR, Falco CM, Slade SS. Carbohydrate administration during a day of sustained aerobic activity improves vigilance, as assessed by a novel ambulatory monitoring device, and mood. Am J Clin Nutr 76: 120‐127, 2002.
 70.Londeree BR. Effect of training on lactate/ventilatory thresholds: A meta‐analysis. Med Sci Sports Exerc 29: 837‐843, 1997.
 71.Lui B, Cuddy JS, Hailes WS, Ruby BC. Seasonal heat acclimatization in wildland firefighters. J Therm Biol 45: 134‐140, 2014.
 72.Margaria R, Aghemo P, Rovelli E. Measurement of muscular power (anaerobic) in man. J Appl Physiol 21: 1662‐1664, 1966.
 73.Marks AN, Sol JA, Domitrovich JW, West MR, Ruby BC. Total energy intake and self‐selected macronutrient distribution during wildland fire suppression. Wilderness Environ Med 31: 188‐196, 2020.
 74.McDermott BP, Anderson SA, Armstrong LE, Casa DJ, Cheuvront SN, Cooper L, Kenney WL, O'Connor FG, Roberts WO. National Athletic Trainers' Association position statement: Fluid replacement for the physically active. J Athl Train 52: 877‐895, 2017.
 75.McGillis Z, Dorman SC, Robertson A, Larivière M, Leduc C, Eger T, Oddson BE, Larivière C. Sleep quantity and quality of Ontario wildland firefighters across a low‐hazard fire season. J Occup Environ Med 59: 1188‐1196, 2017.
 76.Mitten D, Overholt JR, Haynes FI, D'Amore CC, Ady JC. Hiking: A low‐cost, accessible intervention to promote health benefits. Am J Lifestyle Med 12: 302‐310, 2018.
 77.Montain SJ, Baker‐Fulco CJ, Niro PJ, Reinert AR, Cuddy JS, Ruby BC. Efficacy of eat‐on‐move ration for sustaining physical activity, reaction time, and mood. Med Sci Sports Exerc 40: 1970‐1976, 2008.
 78.Montain SJ, Coyle EF. Influence of the timing of fluid ingestion on temperature regulation during exercise. J Appl Physiol (1985) 75: 688‐695, 1993.
 79.Montain SJ, Shippee RL, Tharion WJ. Carbohydrate‐electrolyte solution effects on physical performance of military tasks. Aviat Space Environ Med 68: 384‐391, 1997.
 80.Mota N, Bolton SL, Enns MW, Afifi TO, El‐Gabalawy R, Sommer JL, Pietrzak RH, Stein MB, Asmundson GJG, Sareen J. Course and predictors of posttraumatic stress disorder in the Canadian armed forces: A nationally representative, 16‐year follow‐up study: Cours et prédicteurs du trouble de stress post‐traumatique dans les Forces armées canadiennes: une étude de suivi de 16 ans nationalement représentative. Can J Psychiatr 66 (11): 982‐995, 2021.
 81.Naeher LP, Brauer M, Lipsett M, Zelikoff JT, Simpson CD, Koenig JQ, Smith KR. Woodsmoke health effects: A review. Inhal Toxicol 19: 67‐106, 2007.
 82.Navarro K. Working in smoke:: Wildfire impacts on the health of firefighters and outdoor workers and mitigation strategies. Clin Chest Med 41: 763‐769, 2020.
 83.Navarro KM, Kleinman MT, Mackay CE, Reinhardt TE, Balmes JR, Broyles GA, Ottmar RD, Naher LP, Domitrovich JW. Wildland firefighter smoke exposure and risk of lung cancer and cardiovascular disease mortality. Environ Res 173: 462‐468, 2019.
 84.Nawrot TS, Perez L, Künzli N, Munters E, Nemery B. Public health importance of triggers of myocardial infarction: A comparative risk assessment. Lancet 377: 732‐740, 2011.
 85.Neufer PD. The effect of detraining and reduced training on the physiological adaptations to aerobic exercise training. Sports Med 8: 302‐320, 1989.
 86.Oravisjärvi K, Pietikäinen M, Ruuskanen J, Rautio A, Voutilainen A, Keiski RL. Effects of physical activity on the deposition of traffic‐related particles into the human lungs in silico. Sci Total Environ 409: 4511‐4518, 2011.
 87.Pahnke MD, Trinity JD, Zachwieja JJ, Stofan JR, Hiller WD, Coyle EF. Serum sodium concentration changes are related to fluid balance and sweat sodium loss. Med Sci Sports Exerc 42: 1669‐1674, 2010.
 88.Palmer L, Thandi G, Norton S, Jones M, Fear NT, Wessely S, Rona RJ. Fourteen‐year trajectories of posttraumatic stress disorder (PTSD) symptoms in UK military personnel, and associated risk factors. J Psychiatr Res 109: 156‐163, 2019.
 89.Pasalic E, Hayat MJ, Greenwald R. Air pollution, physical activity, and markers of acute airway oxidative stress and inflammation in adolescents. J Ga Public Health Assoc 6: 314‐330, 2016.
 90.Peters B, Ballmann C, Quindry T, Zehner EG, McCroskey J, Ferguson M, Ward T, Dumke C, Quindry JC. Experimental woodsmoke exposure during exercise and blood oxidative stress. J Occup Environ Med 60: 1073‐1081, 2018.
 91.Petersen A, Payne W, Phillips M, Netto K, Nichols D, Aisbett B. Validity and relevance of the pack hike wildland firefighter work capacity test: A review. Ergonomics 53: 1276‐1285, 2010.
 92.Pimental NA, Pandolf KB. Energy expenditure while standing or walking slowly uphill or downhill with loads. Ergonomics 22: 963‐973, 1979.
 93.Pope CA 3rd, Dockery DW. Health effects of fine particulate air pollution: Lines that connect. J Air Waste Manage Assoc 56: 709‐742, 2006.
 94.Pramsohler S, Wimmer S, Rausch L, Netzer N. Sleep at altitude. Pneumologie 71: 146‐150, 2017.
 95.Psarros C, Theleritis C, Kokras N, Lyrakos D, Koborozos A, Kakabakou O, Tzanoulinos G, Katsiki P, Bergiannaki JD. Personality characteristics and individual factors associated with PTSD in firefighters one month after extended wildfires. Nord J Psychiatry 72: 17‐23, 2018.
 96.Raines J, Snow R, Nichols D, Aisbett B. Fluid intake, hydration, work physiology of wildfire fighters working in the heat over consecutive days. Ann Occup Hyg 59: 554‐565, 2015.
 97.Raines J, Snow R, Petersen A, Harvey J, Nichols D, Aisbett B. Pre‐shift fluid intake: Effect on physiology, work and drinking during emergency wildfire fighting. Appl Ergon 43: 532‐540, 2012.
 98.Raines J, Snow R, Petersen A, Harvey J, Nichols D, Aisbett B. The effect of prescribed fluid consumption on physiology and work behavior of wildfire fighters. Appl Ergon 44: 404‐413, 2013.
 99.Reinhardt TE, Ottmar RD. Baseline measurements of smoke exposure among wildland firefighters. J Occup Environ Hyg 1: 593‐606, 2004.
 100.Rodríguez‐Marroyo JA, López‐Satue J, Pernía R, Carballo B, García‐López J, Foster C, Villa JG. Physiological work demands of Spanish wildland firefighters during wildfire suppression. Int Arch Occup Environ Health 85: 221‐228, 2012.
 101.Rosales AM, Dodds PS, Hailes WS, Sol JA, Coker RH, Quindry JC, Ruby BC. Deterioration of lipid metabolism despite fitness improvements in wildland firefighters. J Occup Environ Med 64: 385‐389, 2022.
 102.Rosales AM, Dodds PS, Sol JA, Marks AN, Domitrovich JW, Ruby BC. Workshift changes in hydration status during wildfire suppression. J Occup Environ Med 63: 963‐969, 2021.
 103.Rosales AM, Hailes WS, Dodds PS, Marks AN, Ruby BC. Influence of fluid delivery schedule and composition on fluid balance, physiologic strain, and substrate use in the heat. Wilderness Environ Med 32 (1): 27‐35, 2021.
 104.Rosales AM, Keck NA, Shriver TC, Schoeller DA, Ruby BC. Septuagenarians approach 4 times the basal metabolic rate during race across America. Int J Sports Physiol Perform 17 (5): 806‐809, 2022.
 105.Rosenbaum S, Stubbs B, Ward PB, Steel Z, Lederman O, Vancampfort D. The prevalence and risk of metabolic syndrome and its components among people with posttraumatic stress disorder: A systematic review and meta‐analysis. Metabolism 64: 926‐933, 2015.
 106.Ruby B, Cuddy J, Hailes W, Dumke C, Slivka DR, Shriver T, Schoeller D. Extreme endurance and the metabolic range of sustained activity is uniquely available for every human not just the elite few. Comp Exerc Physiol 11: 1‐7, 2015.
 107.Ruby BC, Iii GWL, Armstrong DW, Gaskill SE. Wildland firefighter load carriage: Effects on transit time and physiological responses during simulated escape to safety zone. Int J Wildland Fire 12: 111‐116, 2003.
 108.Ruby BC, Schoeller DA, Sharkey BJ, Burks C, Tysk S. Water turnover and changes in body composition during arduous wildfire suppression. Med Sci Sports Exerc 35: 1760‐1765, 2003.
 109.Ruby BC, Shriver TC, Zderic TW, Sharkey BJ, Burks C, Tysk S. Total energy expenditure during arduous wildfire suppression. Med Sci Sports Exerc 34: 1048‐1054, 2002.
 110.Samuel VT, Shulman GI. Nonalcoholic fatty liver disease as a nexus of metabolic and hepatic diseases. Cell Metab 27: 22‐41, 2018.
 111.Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc 39: 377‐390, 2007.
 112.Schleh MW, Ruby BC, Dumke CL. Short term heat acclimation reduces heat stress, but is not augmented by dehydration. J Therm Biol 78: 227‐234, 2018.
 113.Schoeller DA. Measurement of energy expenditure in free‐living humans by using doubly labeled water. J Nutr 118: 1278‐1289, 1988.
 114.Sharkey B. Development and validation of a job‐related work capacity test for wildland firefighters. In: Wildland Firefighter Health and Safety Recommendations of the April 1999 Conference. Missoula, MT: International Association of Wildland Fire, 1999.
 115.Sharkey B, Rothwell T. Validation and field evaluation of a work capacity test for wildland firefighters 467. Med Sci Sports Exerc 28: 79, 1996.
 116.Sharkey BJ, Gaskill SE. Fitness and Work Capacity. USFS publication, Boise, ID, 2009.
 117.Sigsgaard T, Forsberg B, Annesi‐Maesano I, Blomberg A, Bølling A, Boman C, Bønløkke J, Brauer M, Bruce N, Héroux ME, Hirvonen MR, Kelly F, Künzli N, Lundbäck B, Moshammer H, Noonan C, Pagels J, Sallsten G, Sculier JP, Brunekreef B. Health impacts of anthropogenic biomass burning in the developed world. Eur Respir J 46: 1577‐1588, 2015.
 118.Silcox F. Fire Prevention and Control on the National Forests Yearbook of the Department of Agriculture. Government Priting Office, Washington, 1911. https://foresthistory.org/wp‐content/uploads/2017/01/Silcox_Fire_1910.pdf
 119.Sol JA, Domitrovich JW, Ruby BC, Gaskill SE, Dumke CL. In reply to Drs McAnaney and Ganti. Wilderness Environ Med 30: 217‐218, 2019.
 120.Sol JA, Ruby BC, Gaskill SE, Dumke CL, Domitrovich JW. Metabolic demand of hiking in wildland firefighting. Wilderness Environ Med 29: 304‐314, 2018.
 121.Sol JA, West MR, Domitrovich JW, Ruby BC. Evaluation of environmental conditions on self‐selected work and heat stress in wildland firefighting. Wilderness Environ Med 32: 149‐159, 2021.
 122.Sommer JL, Mota N, Thompson JM, Asmundson GJ, Sareen J, Bernstein CN, Marrie RA, El‐Gabalawy R. Associations between courses of posttraumatic stress disorder and physical health conditions among Canadian military personnel. J Anxiety Disord 87: 102543, 2022.
 123.Thurber C, Dugas LR, Ocobock C, Carlson B, Speakman JR, Pontzer H. Extreme events reveal an alimentary limit on sustained maximal human energy expenditure. Sci Adv 5: eaaw0341, 2019.
 124.Trappe TA, Gastaldelli A, Jozsi AC, Troup JP, Wolfe RR. Energy expenditure of swimmers during high volume training. Med Sci Sports Exerc 29: 950‐954, 1997.
 125.Tunno B, Longley I, Somervell E, Edwards S, Olivares G, Gray S, Cambal L, Chubb L, Roper C, Coulson G, Clougherty JE. Separating spatial patterns in pollution attributable to woodsmoke and other sources, during daytime and nighttime hours, in Christchurch, New Zealand. Environ Res 171: 228‐238, 2019.
 126.U.S. Global Change Research Program. The Impacts of Climate Change on Human Health in the United States: A Scientific Assessment 2016.
 127.Vincent G, Ferguson SA, Tran J, Larsen B, Wolkow A, Aisbett B. Sleep restriction during simulated wildfire suppression: Effect on physical task performance. PLoS One 10: e0115329, 2015.
 128.Vincent GE, Aisbett B, Hall SJ, Ferguson SA. Fighting fire and fatigue: Sleep quantity and quality during multi‐day wildfire suppression. Ergonomics 59: 932‐940, 2016.
 129.Vincent GE, Aisbett B, Larsen B, Ridgers ND, Snow R, Ferguson SA. The impact of heat exposure and sleep restriction on firefighters' work performance and physiology during simulated wildfire suppression. Int J Environ Res Public Health 14: 180, 2017.
 130.Vodovotz Y, Barnard N, Hu FB, Jakicic J, Lianov L, Loveland D, Buysse D, Szigethy E, Finkel T, Sowa G, Verschure P, Williams K, Sanchez E, Dysinger W, Maizes V, Junker C, Phillips E, Katz D, Drant S, Jackson RJ, Trasande L, Woolf S, Salive M, South‐Paul J, States SL, Roth L, Fraser G, Stout R, Parkinson MD. Prioritized research for the prevention, treatment, and reversal of chronic disease: Recommendations from the lifestyle medicine research summit. Front Med (Lausanne) 7: 585744, 2020.
 131.Werdermann M, Berger I, Scriba LD, Santambrogio A, Schlinkert P, Brendel H, Morawietz H, Schedl A, Peitzsch M, King AJF, Andoniadou CL, Bornstein SR, Steenblock C. Insulin and obesity transform hypothalamic‐pituitary‐adrenal axis stemness and function in a hyperactive state. Mol Metab 43: 101112, 2021.
 132.West MR, Costello S, Sol JA, Domitrovich JW. Risk for heat‐related illness among wildland firefighters: Job tasks and core body temperature change. Occup Environ Med 77: 433‐438, 2020.
 133.Westerterp KR, Kayser B, Brouns F, Herry JP, Saris WH. Energy expenditure climbing Mt. Everest. J Appl Physiol (1985) 73: 1815‐1819, 1992.
 134.Westerterp KR, Plasqui G, Goris AH. Water loss as a function of energy intake, physical activity and season. Br J Nutr 93: 199‐203, 2005.
 135.Westerterp KR, Saris WH, van Es M, ten Hoor F. Use of the doubly labeled water technique in humans during heavy sustained exercise. J Appl Physiol (1985) 61: 2162‐2167, 1986.
 136.Williams‐Bell FM, Aisbett B, Murphy BA, Larsen B. The effects of simulated wildland firefighting tasks on core temperature and cognitive function under very hot conditions. Front Physiol 8: 815, 2017.
 137.Wolkow A, Aisbett B, Jefferies S, Main LC. Effect of heat exposure and simulated physical firefighting work on acute inflammatory and cortisol responses. Ann Work Expo Health 61: 600‐603, 2017.
 138.Wolkow A, Aisbett B, Reynolds J, Ferguson SA, Main LC. Relationships between inflammatory cytokine and cortisol responses in firefighters exposed to simulated wildfire suppression work and sleep restriction. Physiol Rep 3: e12604, 2015.
 139.Wolkow A, Aisbett B, Reynolds J, Ferguson SA, Main LC. Acute psychophysiological relationships between mood, inflammatory and cortisol changes in response to simulated physical firefighting work and sleep restriction. Applied Psychophysiol Biofeedback 41: 165‐180, 2016.
 140.Wolkow A, Ferguson SA, Vincent GE, Larsen B, Aisbett B, Main LC. The impact of sleep restriction and simulated physical firefighting work on acute inflammatory stress responses. PLoS One 10: e0138128, 2015.
 141.Xu MX, Ge CX, Qin YT, Gu TT, Lou DS, Li Q, Hu LF, Feng J, Huang P, Tan J. Prolonged PM2.5 exposure elevates risk of oxidative stress‐driven nonalcoholic fatty liver disease by triggering increase of dyslipidemia. Free Radic Biol Med 130: 542‐556, 2019.
 142.Zong C, Song G, Yao S, Guo S, Yu Y, Yang N, Guo Z, Qin S. Cigarette smoke exposure impairs reverse cholesterol transport which can be minimized by treatment of hydrogen‐saturated saline. Lipids Health Dis 14: 159, 2015.

Contact Editor

Submit a note to the editor about this article by filling in the form below.

* Required Field

Article Title: Physiology of the Wildland Firefighter: Managing Extreme Energy Demands in Hostile, Smoky, Mountainous Environments
 

How to Cite

Brent C. Ruby, Robert H. Coker, Joe Sol, John Quindry, Scott J. Montain. Physiology of the Wildland Firefighter: Managing Extreme Energy Demands in Hostile, Smoky, Mountainous Environments. Compr Physiol 2023, 13: 4587-4615. doi: 10.1002/cphy.c220016