title: Fluid intake, hydration, work physiology of wildfire fighters working in the heat over consecutive days.
abstract: OBJECTIVE
  (i) To evaluate firefighters' pre- and post-shift hydration status across two shifts of wildfire suppression work in hot weather conditions. (ii) To document firefighters' fluid intake during and between two shifts of wildfire suppression work. (iii) To compare firefighters' heart rate, activity, rating of perceived exertion (RPE), and core temperature across the two consecutive shifts of wildfire suppression work.
  
  
  METHODS
  Across two consecutive days, 12 salaried firefighters' hydration status was measured immediately pre- and post-shift. Hydration status was also measured 2h post-shift. RPE was also measured immediately post-shift on each day. Work activity, heart rate, and core temperature were logged continuously during each shift. Ten firefighters also manually recorded their food and fluid intake before, during, and after both fireground shifts.
  
  
  RESULTS
  Firefighters were not euhydrated at all measurement points on Day one (292±1 mOsm l(-1)) and euhydrated across these same time points on Day two (289±0.5 mOsm l(-1)). Fluid consumption following firefighters' shift on Day one (1792±1134ml) trended (P = 0.08) higher than Day two (1108±1142ml). Daily total fluid intake was not different (P = 0.27), averaging 6443±1941ml across both days. Core temperature and the time spent ≥ 70%HRmax were both elevated on Day one (when firefighters were not euhydrated). Firefighters' work activity profile was not different between both days of work.
  
  
  CONCLUSIONS
  There was no difference in firefighters' pre- to post-shift hydration within each shift, suggesting ad libitum drinking was at least sufficient to maintain pre-shift hydration status, even in hot conditions. Firefighters' relative hypohydration on Day one (despite a slightly lower ambient temperature) may have been associated with elevations in core temperature, more time in the higher heart rate zones, and 'post-shift' RPE.
authors: 1.Centre for Physical Activity and Nutrition Research, Australia Research, Deakin University, Burwood 3125, Australia 2.Bushfire Co-Operative Research Centre, East Melbourne 3002, Australia.
authors: Jenni
authors: J
authors: Raines
authors: 1.Centre for Physical Activity and Nutrition Research, Australia Research, Deakin University, Burwood 3125, Australia.
authors: Rodney
authors: R
authors: Snow
authors: 2.Bushfire Co-Operative Research Centre, East Melbourne 3002, Australia 3.Research and Innovation, Country Fire Authority, Burwood 3151, Australia.
authors: David
authors: D
authors: Nichols
authors: 1.Centre for Physical Activity and Nutrition Research, Australia Research, Deakin University, Burwood 3125, Australia 2.Bushfire Co-Operative Research Centre, East Melbourne 3002, Australia brad.aisbett@deakin.edu.au.
authors: Brad
authors: B
authors: Aisbett
mesh_terms: D000293:Adolescent; D000328:Adult; D001833:Body Temperature Regulation / Q000502:physiology*; D003681:Dehydration / Q000209:etiology / Q000517:prevention & control*; D004326:Drinking; D061388:Firefighters; D005440:Fluid Therapy; D006339:Heart Rate / Q000502:physiology; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D016273:Occupational Exposure / Q000009:adverse effects; D005082:Physical Exertion / Q000502:physiology; D014937:Work; D055815:Young Adult
keywords: activity; firefighters; thermoregulation.