Human thermoregulatory responses during heat exposure after artificially induced sunburn.
Thermoregulatory responses in the heat (ambient temperature 49 degrees C, 20% relative humidity, 1 m/s wind) were investigated in 10 unacclimated men during 50 min of cycle ergometer exercise (approximately 53% of maximal aerobic power) after a 10-min rest before as well as 24 h and 1 wk after twice the minimal erythemal dose of UV-B radiation that covered approximately 85% of the body surface area. In 7 subjects esophageal temperature (Tes) was recorded while in all 10 subjects five-site skin and rectal temperatures, heart rate, and back, left forearm, and shielded (12 cm2 area) right forearm sweating rates (msw) were recorded at 15-s intervals. Venous blood was collected before and after exercise-heat stress. Mean skin temperature, Tes, rectal temperature, heart rate, and total body sweating rate were not significantly (P greater than 0.05) affected by sunburn. Pre- and postexercise values of hematocrit, hemoglobin, plasma protein, plasma volume, and plasma osmolality were also not affected (P greater than 0.05) by sunburn. Analysis of presunburn and post-sunburn data showed that the Tes intercept for sweating (degrees C) was unaffected (P greater than 0.05), but msw/Tes and final msw from the left forearm (msw/Tes 0.24 +/- 0.02 vs. 0.17 +/- 0.01 mg.cm-2.min-1. degrees C-1, P less than 0.05; msw 0.60 +/- 0.05 vs. 0.37 +/- 0.02, mg.cm-2.min-1, P less than 0.05) and back (msw/Tes 0.43 +/- 0.03 vs. 0.36 +/- 0.01 mg.cm-2.min-1. degrees C-1, P = 0.052; msw 1.08 +/- 0.09 vs. 0.74 +/- 0.05 mg.cm-2.min-1, P less than 0.05) were significantly reduced 24 h postsunburn.(ABSTRACT TRUNCATED AT 250 WORDS)
Pandolf
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KB
US Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760-5007.
Gange
R W
RW
Latzka
W A
WA
Blank
I H
IH
Kraning
K K
KK
Gonzalez
R R
RR
D000328:Adult; D001831:Body Temperature; D001833:Body Temperature Regulation; D004781:Environmental Exposure; D004947:Esophagus / Q000502:physiology; D015444:Exercise; D006358:Hot Temperature; D006801:Humans; D008297:Male; D012007:Rectum / Q000502:physiology; D012649:Self Concept; D012881:Skin Temperature; D013312:Stress, Physiological / Q000503:physiopathology; D013471:Sunburn / Q000097:blood / Q000378:metabolism / Q000503:physiopathology*; D013697:Thermosensing; D014466:Ultraviolet Rays