title: Total energy expenditure during arduous wildfire suppression.
abstract: OBJECTIVE
  The purpose of this investigation was to determine the total energy expenditure (TEE) by using the doubly labeled water (DLW) methodology during 5 d of wildfire suppression in Montana, California, Florida, Washington, and Idaho.
  
  
  METHODS
  Seventeen wildland firefighters (from three Interagency Hot Shot crews, N = 8 men, height = 177 +/- 7 cm, weight = 74.6 +/- 6.4 kg, age = 24.5 +/- 1.8 yr; N = 9 women, height = 170 +/- 7 cm, weight = 65.2 +/- 8.0 kg, age = 25.0 +/- 1.3 yr) served as subjects. Before wildland fire suppression, each subject was given an oral dose of 2H2O and H218O (approximately 0.23 g 2H2O.kg estimated TBW-1 and 0.39 g H218O.kg estimated TBW-1). Urine samples were collected between 0400 and 0600 daily. TEE was calculated using the two-point method for days 1-3 and 1-5, with the TEE for days 4-5 calculated by extrapolation. Urine samples from other crew members not participating in the DLW protocol were collected at the same times and used to adjust calculations of isotopic elimination for background shifts.
  
  
  RESULTS
  TEE was 17.4 +/- 3.7 and 17.5 +/- 6.9 MJ.d-1 during days 1-3 and 4-5, respectively. The energy expenditure associated with physical activity (EEA) was 8.8 +/- 3.0 and 8.9 +/- 6.1 MJ.d-1 for days 1-3 and 4-5, respectively.
  
  
  CONCLUSIONS
  The current data demonstrate consistently high daily energy expenditure in the wildland firefighter. These data also demonstrate that the doubly labeled water methodology is an appropriate methodology for the measure of TEE during unpredictable field operations if adjustments are made for changes in background enrichment and elevated water turnover.
authors.affiliation: Human Performance Laboratory, The University of Montana, Missoula 59812-1825, USA. ruby@selway.umt.edu
authors.forename: Brent C
authors.initials: BC
authors.lastname: Ruby
authors.forename: Tim C
authors.initials: TC
authors.lastname: Shriver
authors.forename: Theodore W
authors.initials: TW
authors.lastname: Zderic
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Sharkey
authors.forename: Catherine
authors.initials: C
authors.lastname: Burks
authors.forename: Sonja
authors.initials: S
authors.lastname: Tysk
mesh_terms: D000328:Adult; D002153:Calorimetry, Indirect / Q000379:methods; D002149:Energy Intake / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D005390:Fires / Q000517:prevention & control*; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D012737:Sex Factors; D014937:Work / Q000502:physiology*