Development of a Comprehensive Thermoregulatory Model for Exercise and Resting Response in Women Exposed to Thermal Stress Wearing Military Clothing.
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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Three separate studies were conducted in this project a resting study on six women several thermoregulatory modeling projects and an exercisecold stress study on nine women. Effects of the menstrual cycle on heat loss and heat production M, core Tc, and skin temperature responses were studied in six unacclimatized, women nonsmokers ages 18-29 yr, resting supine. Each women was exposed to a cold ramp Ta 20 deg C to -5 deg C, -0.32 deg Cmin, rh 50 - 2, V 1ms in the follicular phase F days 2-6 and mid luteal phase L days 19-23 of her menstrual cycle. It was shown that extensive peripheral vasoconstriction in F during early periods of the ramp generally elevated resting Tes above thermoneutral levels. Shivering thermogenesis was highly correlated with Mean weighted skin temperature, and finger temperature. There was a reduced slope in the M as a function of mean body thermal drive in L experiments when dressed in BDUs P 0.02 and BDU BDOs P 0.01. Heat flux was higher and cold debt was less in the L phases when dressed in BDUs. The modeling study showed that, several cold model equations appear to be applicable for depicting shivering thermogenesis provided the dominant thermal drive is not from decreasing core temperature and cold adrenergic drives and individuals are within a range of body fat between 8 to 30. In the exercise study, nine healthy women were exposed to a cold challenge as in the resting experiments during their early follicular F and mid luteal ML phases. The women walked on a treadmill at a work rate of 32 VO2max dressed in BDUs parka. During submaximal exercisecold stress, control of ventilation and cardiac output was found to be linked with altered core temperature Tc but the sweating and heat exchange requirements are driven by thermoregulatory adjustments appearing during a womans menstrual cycle.
- Anatomy and Physiology
- Medicine and Medical Research
- Stress Physiology