Why the luteal phase feels harder
The luteal phase follows ovulation and lasts until menstruation begins, roughly the second half of the cycle. Progesterone rises and estrogen has a secondary smaller rise then falls. Progesterone slightly raises resting core body temperature and can increase ventilation and perceived effort, and many women report more fatigue, higher heart rate at a given workload, and reduced tolerance for heat in the late luteal phase.
As with cycle research generally, average performance effects across phases are often small and inconsistent in controlled studies, so the experience varies considerably between individuals.
Adjusting load and recovery
A common practical approach is to keep training but lean toward moderate loads, prioritize recovery, hydration, and heat management, and listen to readiness rather than forcing peak intensity, especially in the days before menstruation. Some women train hard throughout with no issue; the point is to match effort to how recovery and energy actually feel.
This is general educational information, not medical advice. Responses depend on the individual, contraception, and any conditions, so personalize with tracking and qualified professional input.