Seasonal changes in wildland firefighter fitness and body composition
Steven E. Gaskill A , Charles L. Dumke
A , Charles G. Palmer A , Brent C. Ruby B , Joseph W. Domitrovich C D and Joseph A. Sol C
A School of Integrative Physiology and Athletic Training, University of Montana, Missoula, MT 59812, USA.
B Montana Center for Work Physiology and Exercise Metabolism, University of Montana, Missoula, MT 59812, USA.
C US Forest Service, National Technology and Development Program, United States Department of Agriculture, 5785 Highway 10 W, Missoula, MT 59808, USA.
D Corresponding author. Email: joseph.domitrovich@usda.gov
International Journal of Wildland Fire 29(3) 294-303 https://doi.org/10.1071/WF19104
Submitted: 11 July 2019 Accepted: 6 December 2019 Published: 11 February 2020
Abstract
Hiking with a pack is the highest-intensity task that wildland firefighters (WLFFs) perform during sustained activities related to wildland fire suppression. Firefighters perform this and other tasks together as a crew; this provides a unique model to evaluate select physical and physiological changes in members of working crews over a fire season during extended operations. The objective of this study was to evaluate changes in peak aerobic fitness (VO2peak), sustainable aerobic fitness at the ventilatory threshold (VO2vt) and body composition over a 5-month wildland fire season. WLFFs from four crews (55 males, 10 females) participated in a maximal graded exercise treadmill test and body composition evaluation pre- and post season. VO2peak values and variance did not change across the fire season (pre = 3.96 ± 0.65, post = 3.96 ± 0.69 L min−1, not significant). VO2vt average decreased slightly while variance decreased greatly within each crew (pre = 37.5 ± 7.0, post = 35.4 ± 2.3 mL kg−1 min−1, P < 0.05). There was an improvement in VO2vt in initially less-fit WLFFs and a VO2vt decrease in initially more-fit WLFFs. WLFFs lost fat mass (−1.56 ±−1.06 kg, P < 0.01) and fat-free mass (−0.38 ±−1.24 kg, P < 0.05). Post-season VO2vt values were the same as the higher range of the documented metabolic cost of uphill load carriage and reveal a unique group adaptation to extended physical demands.
Additional keywords: aerobic fitness, group training, occupational fitness, training adaptations.
References
Borg G (1962) ‘Physical performance and perceived exertion.’ (C. W. K. Gleerup: Copenhagen, Denmark)Broyles G (2011) Fireline production rates. USDA Forest Service, National Technology and Development Program, Technical Report 1151 1805-SDTDC. (San Dimas, CA, USA)
Budd GM, Brotherhood JR, Hendrie AL, Jeffery SE, Beasley FA, Costin BP, Wu Z, Baker MM, Cheney NP, Dawson MP (1997) Project Aquarius 10. Effects of work, weather, and fire on the energy expenditure, strain, and productivity of men suppressing wildland fires. International Journal of Wildland Fire 7, 167–180.
| Project Aquarius 10. Effects of work, weather, and fire on the energy expenditure, strain, and productivity of men suppressing wildland fires.Crossref | GoogleScholarGoogle Scholar |
Bugyi B (1973) Estimation of the residual volume of the lungs by anthropometrical determinations. The Journal of Sports Medicine and Physical Fitness 3, 191–193.
Coker RH, Murphy CJ, Johannsen M, Galvin G, Ruby BC (2019) Wildlife firefighting: adverse influence on indices of metabolic and cardiovascular health. Journal of Occupational and Environmental Medicine 61, e91–e94.
| Wildlife firefighting: adverse influence on indices of metabolic and cardiovascular health.Crossref | GoogleScholarGoogle Scholar | 30640843PubMed |
Collins CN, Brooks RH, Sturz BD, Nelson AS, Keefe RF (2018) Body composition changes of United States smokejumpers during the 2017 fire season. Fire 1, 48
| Body composition changes of United States smokejumpers during the 2017 fire season.Crossref | GoogleScholarGoogle Scholar |
Cooper JA, Nguyen DD, Ruby BC, Schoeller DA (2011) Maximal sustained levels of energy expenditure in humans during exercise. Medicine and Science in Sports and Exercise 43, 2359–2367.
| Maximal sustained levels of energy expenditure in humans during exercise.Crossref | GoogleScholarGoogle Scholar | 21606870PubMed |
Cuddy JS, Gaskill SE, Sharkey BJ, Harger SG, Ruby BC (2007) Supplemental feedings increase self-selected work output during wildfire suppression. Medicine and Science in Sports and Exercise 39, 1004–1012.
| Supplemental feedings increase self-selected work output during wildfire suppression.Crossref | GoogleScholarGoogle Scholar | 17545892PubMed |
Cuddy JS, Slivka DR, Tucker TJ, Hailes WS, Ruby BC (2011) Glycogen levels in wildland firefighters during wildfire suppression. Wilderness & Environmental Medicine 22, 23–27.
| Glycogen levels in wildland firefighters during wildfire suppression.Crossref | GoogleScholarGoogle Scholar |
Cuddy JS, Sol JA, Hailes WS, Ruby BC (2015) Work patterns dictate energy demands and thermal strain during wildland firefighting. Wilderness & Environmental Medicine 26, 221–226.
| Work patterns dictate energy demands and thermal strain during wildland firefighting.Crossref | GoogleScholarGoogle Scholar |
Gaskill SE, Ruby BC, Walker AJ, Sanchez OA, Serfass RC, Leon AS (2001a) Validity and reliability of combining three methods to determine ventilatory threshold. Medicine and Science in Sports and Exercise 33, 1841–1848.
| Validity and reliability of combining three methods to determine ventilatory threshold.Crossref | GoogleScholarGoogle Scholar | 11689733PubMed |
Gaskill SE, Walker AJ, Serfass RA, Bouchard C, Gagnon J, Rao DC, Skinner JS, Wilmore JH, Leon AS (2001b) Changes in ventilatory threshold with exercise training in a sedentary population: the HERITAGE Family Study. International Journal of Sports Medicine 22, 586–592.
| Changes in ventilatory threshold with exercise training in a sedentary population: the HERITAGE Family Study.Crossref | GoogleScholarGoogle Scholar | 11719894PubMed |
Hydren JR, Cohen BS (2015) Current scientific evidence for a polarized cardiovascular endurance training model. Journal of Strength and Conditioning Research 29, 3523–3530.
| Current scientific evidence for a polarized cardiovascular endurance training model.Crossref | GoogleScholarGoogle Scholar | 26595137PubMed |
Kuipers H (1998) Training and overtraining: an introduction. Medicine and Science in Sports and Exercise 30, 1137–1139.
| Training and overtraining: an introduction.Crossref | GoogleScholarGoogle Scholar | 9662685PubMed |
Laursen BB (2010) Training for intense exercise performance: high-intensity or high-volume training? Scandinavian Journal of Medicine & Science in Sports 20, 1–10.
| Training for intense exercise performance: high-intensity or high-volume training?Crossref | GoogleScholarGoogle Scholar |
Lui B, Cuddy JS, Hailes WS, Ruby BC (2014) Seasonal heat acclimatization in wildland firefighters. Journal of Thermal Biology 45, 134–140.
| Seasonal heat acclimatization in wildland firefighters.Crossref | GoogleScholarGoogle Scholar | 25436962PubMed |
Pandolf KB, Givoni B, Goldman RF (1977) Predicting energy expenditure with loads while standing or walking very slowly. Journal of Applied Physiology: Respiratory, Environmental and Exercise Physiology 43, 577–581.
| Predicting energy expenditure with loads while standing or walking very slowly.Crossref | GoogleScholarGoogle Scholar |
Petersen A, Payne W, Phillips M, Netto K, Nichols D, Aisbett B (2010) Validity and relevance of the pack hike wildland firefighter work capacity test: a review. Ergonomics 53, 1276–1285.
| Validity and relevance of the pack hike wildland firefighter work capacity test: a review.Crossref | GoogleScholarGoogle Scholar | 20865610PubMed |
Rodríguez-Marroyo JA, Villa JG, López-Satue J, Pernía R, Carballo B, García-López J, Foster C (2011) Physical and thermal strain of firefighters according to the firefighting tactics used to suppress wildfires. Ergonomics 54, 1101–1108.
| Physical and thermal strain of firefighters according to the firefighting tactics used to suppress wildfires.Crossref | GoogleScholarGoogle Scholar | 22026953PubMed |
Ruby BC, Shriver TC, Zderic TW, Sharkey BJ, Burks C, Tysk S (2002) Total energy expenditure during arduous wildfire suppression. Medicine and Science in Sports and Exercise 34, 1048–1054.
| Total energy expenditure during arduous wildfire suppression.Crossref | GoogleScholarGoogle Scholar | 12048336PubMed |
Seiler S (2010) What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance 5, 276–291.
| What is best practice for training intensity and duration distribution in endurance athletes?Crossref | GoogleScholarGoogle Scholar | 20861519PubMed |
Sharkey BJ (1999) Demands of the job. In ‘Wildland firefighter health and safety: recommendations of the April 1999 conference’, 26–29 April 1999, Missoula, MT, USA. USDA Forest Service, National Technology and Development Program Publication 9951–2841-MTDC. pp. 21–26. (Missoula, MT, USA)
Sharkey BJ, Gaskill SE (2009) Fitness and work capacity. National Wildfire Coordinating Group Publication PMS 304–2, NFES 1956. (National Wildfire Coordinating Group: Boise, ID, USA) Available at https://www.nwcg.gov/sites/default/files/publications/pms304-2.pdf [Verified 17 December 2019]
Sol JA, Ruby BC, Gaskill SE, Dumke CL, Domitrovich JW (2018) Metabolic demand of hiking in wildland firefighting. Wilderness & Environmental Medicine 29, 304–314.
| Metabolic demand of hiking in wildland firefighting.Crossref | GoogleScholarGoogle Scholar |
Steinkamp RC, Cohen NL, Gaffey WR, McKey T, Bron G, Siri WE, Sargent TW, Isaacs E (1965) Measures of body fat and related factors in normal adults – II: a simple clinical method to estimate body fat and lean body mass. Journal of Chronic Diseases 18, 1291–1307.
| Measures of body fat and related factors in normal adults – II: a simple clinical method to estimate body fat and lean body mass.Crossref | GoogleScholarGoogle Scholar | 5852581PubMed |
Thomas S, Reading J, Shephard RJ (1992) Revision of the physical activity readiness questionnaire (PAR-Q). Canadian Journal of Sport Sciences 4, 338–345.
