Thermoregulation in Women: Effect of the Menstrual Cycle.
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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Twelve women participated in seven different experimental protocols which characterized the effect of the mid-luteal phase elevation in core temperature during exercise and heat exposure. Experiments were conducted at ambient temperatures between 30 deg and 50 deg at both low and high ambient water vapor pressures when test subjects were not naturally acclimatized or artificially acclimated to the heat. In all experiments, the separation of temperatures between the early follicular and mid-luteal phases was apparent, with temperature in the mid-luteal phase averaging 0.3 to 0.5 deg higher than in the early follicular phase. This significant difference observed in resting core esophageal temperature between the two menstrual cycle phases studied in these experiments was maintained during exercise during both cycling and walking exercise, in both hot and very hot ambient temperatures, in both humid and dry conditions, and when heavy or light clothing was worn. Heart rate, skin temperatures and sweating rates were variable between test protocols. In summary, the change in resting and exercise core temperature between the mid-luteal and early follicular phases of the menstrual cycle was significant and of the same magnitude as observed as a result of changes in circadian timing, heat acclimation, exercise training or during dehydration.
- Anatomy and Physiology