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Progesterone is a steroid hormone produced primarily by the corpus luteum after ovulation, with secondary production in the adrenal glands and, during pregnancy, the placenta. (source) In cycling females, it rises sharply in the luteal phase of the menstrual cycle, working in concert with estrogen to regulate the reproductive system, uterine environment, and a range of systemic physiological processes.
For performance, progesterone has meaningful effects on thermoregulation, ventilatory drive, sleep quality, and substrate utilization. (source) Elevated luteal-phase progesterone raises core body temperature and increases the ventilatory response to CO2 — both of which affect perceived exertion and heat tolerance during training. (source)
