INFLUENCE OF HYDRATION STATUS AND FLUID REPLACEMENT ON HEAT TOLERANCE WHILE WEARING NBC PROTECTIVE CLOTHING

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Authors
  1. Cheung, S.S.
  2. MacLellan, T.M.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
The purpose of the present study was to investigate the influence of hypohydration and fluid replacement on tolerance to an uncompensable heat stress. Eight healthy young males completed a matrix of six trials in an environmental chamber, set at 40C and 30% relative humidity, while waring nuclear, biological, and chemical protective clothing. Subjects performed either light (3.5 km h 1(-), 0% grade, no wind) or heavy (4.8 km h 1(-), 4% grade, no wind) treadmill exercise combined with three hydration states (euhydration with fluid replacement (EU/F), euhydration without fluid replacement (EU/NF), and hypohydration with fluid replacement (H/F). Hypohydration of 2.2% body mass was achieved by exercise and fluid restriction on the day preceding the trials. No differences in the endpoint mean skin temperature (Tsk), sweat rate, or rectal temperature (Tre) were observed among the hydration conditions for either work rate. During light exercise, the change in Tre (finite difference Tre) was significantly higher with H/F than EU/F after 40 min, and heart rate was greater after 25 min. The heart rate was greater during EU/NF than during EU/F after 60 min. Tolerance times were significantly greater for EU/F than for either EU/NF or H/F. With heavy exercise, no differences in infinite difference Tre were observed across hydration conditions. TRUNCATED
Keywords
Hypohydration;Heat exhaustion;Temperature regulation;Fluid replacement;Cardiac output
Report Number
DCIEM-96-P-38 — Reprint; Paper
Date of publication
17 Jun 1997
Number of Pages
10
Reprinted from
Eur J Appl Physiol, vol 77, 1998, p 139-148
DSTKIM No
98-00413
CANDIS No
507332
Format(s):
Hardcopy;Document Image stored on Optical Disk

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