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PURPOSE This study determined whether exercise (30 min)-rest (10 min) cycles alter physiologic tolerance to uncompensable heat stress (UCHS) when outdoors in the desert. In addition, the relationship between core temperature and exhaustion from heat strain previously established in laboratory studies was compared with field studies. METHODS Twelve men(More)
A lumped-parameter model of a fingertip is presented. The semispherical model includes the effects of heat storage, heat exchange with the environment, and heat transport by blood perfusion. The thermal insulation on the surface of the fingertip is represented by the overall heat transfer coefficient that is calculated by common engineering formulas. The(More)
Five fit men completed a practice, control, and sleep deprivation exercise test. Two nights of normal sleep preceded the control test, and 33 h of wakefulness preceded the sleep deprivation test. These tests consisted of 20 min of rest followed by 40 min of cycle-ergometer exercise (50% of peak O2 uptake, VO2) in a temperate (ambient temperature, 28 degrees(More)
Over the last two decades, our laboratory has been establishing the data base and developing a series of predictive equations for deep body temperature, heart rate and sweat loss responses of clothed soldiers performing physical work at various environmental extremes. Individual predictive equations for rectal temperature, heart rate and sweat loss as a(More)
The effect of acute hypobaric hypoxia on local sweating and cutaneous blood flow was studied in four men and four women (follicular phase of menstrual cycle), who exercised at 60% of their altitude-specific peak aerobic power for 35 min at barometric pressures (PB) of 770 Torr (sea level), 552 Torr (2,596 m), and 428 Torr (4,575 m) at an ambient temperature(More)
BACKGROUND Altered thermoregulation has been reported following spaceflight simulations (bed rest and water immersion) but has never been examined after actual spaceflight. HYPOTHESIS We tested the null hypothesis that body temperatures and heat loss responses during exercise would be similar before and after spaceflight. METHODS Two male crewmembers of(More)
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,(More)
Core temperature (Tc) output comparisons were analyzed from thermal models applicable to persons wearing protective clothing. The two models evaluated were the United States (US) Army Research Institute of Environmental Medicine (USARIEM) heat strain experimental model and the United Kingdom (UK) Loughborough (LUT25) model. Data were derived from(More)
Time-weighted averaging is a traditional method used in heat stress analyses to approximate, in terms of a single continuous level of heat production, the rate of heat production from complex intermittent exercise patterns. Physiological responses during intermittent and continuous exercise were studied in four subjects exposed to heat stress in which(More)