Temperature Regulation at Rest and Exercise during the Human Menstrual Cycle,

Thermoregulatory responses were studied in eight women during three separate experimental protocols in both the follicular F and luteal L phases of the menstrual cycle. Continuous measurements of esophageal temperature T sub es, mean skin temperature T sub sk, metabolism, and forearm sweating m sub s were made during all experiments. Study I evaluated 35 minutes of seated cycle exercise. Study II involved both passive heat exposure and seated cycle exercise to elicit a 0.8 C increase in T sub es. Study III evaluated high intensity exercise. The normal L increase in resting T sub es occurred in all eight subjects. T sub sk was higher during L than F in all experiments. During exercise, the T sub es threshold for sweating was higher in L, with no change in the slope of m sub s to T sub es between menstrual cycle phases. This rightward shift in T sub es averaged 0.53 C for all conditions studied. Temperature regulation in healthy women varies with menstrual cycle phase as the onset of sweating occurs at an elevated T sub es threshold in the luteal phase when resting core temperature is elevated.