Thermoregulatory responses to cold: effects of handwear with multi-layered clothing.
BACKGROUND
Thermoregulatory responses were studied during rest and exercise in men wearing diverse handwear with an extended cold-weather clothing system [ECWCS]. The ECWCS (thermal insulation = 3.6 clo (1 clo = thermal resistance approximately 0.155 m2.K.W(-1)); weight = 10.1 kg) incorporates skin-tight polypropylene underwear, polyester/cotton fatigues, polyester-insulated liners, balaclava, vapor-barrier boots, and polytetrafluroethylene [PTFE]-lined outer garments.


METHODS
Six fit males each rested (M = 71 W.m(-2) and performed treadmill exercise (M = 171 W.m(-2)) while wearing the following handwear with the ECWCS: a light duty glove (LD, clo = 0.86), a heavy duty glove (HD, clo = 1.05), or an Arctic mitten (AM, clo = 1.46). Cold exposures were at Ta = 0 degrees C, -20 degrees C, and -30 degrees C; rh = 20%; wind speed = 10.34 m.s(-1). Exposure was a target period of 120 min designated as maximal endurance time (ET, min). All experiments were performed on separate days. Rectal (Tre), middle finger (Tmf), and mean weighted skin (Tsk) temperatures were recorded continuously; oxygen uptake and heart rate were measured periodically and total body weight loss msw, g.h(-1)) was determined after each run.


RESULTS
During rest at 0 degrees C, the ECWCS maintained Tre at 37 degrees C for the maximal ET with all handwear configurations; for each lower ambient condition, steady-state Tre dropped -0.2 degrees C per each 10 C decrease in Ta.Tmf at or near 5 degrees C prior to the maximal ET was the basis for premature attrition; Tsk of 29.4 degrees C was associated with subjective thermal discomfort. ET was predicted adequately by combining Tmf, heat production, Tre and Tsk.


CONCLUSIONS
The ECWCS with specific handwear furnish adequate ET in cold-dry ambients provided that ventilation and removal of extra layers is an option during heavy exercise and thermal insulation is not decreased by body moisture.
Gonzalez
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RR
U.S. Army Research Institute of Environmental Medicine, Natick, MA, USA.
Endrusick
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TL
Santee
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WR
D000328:Adult; D001831:Body Temperature; D001833:Body Temperature Regulation / Q000502:physiology*; D003080:Cold Temperature / Q000009:adverse effects*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D017575:Gloves, Protective / Q000592:standards*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008889:Military Personnel; D010101:Oxygen Consumption; D012146:Rest / Q000502:physiology*; D013997:Time Factors; D014481:United States; D015431:Weight Loss / Q000502:physiology; D014919:Wind