The hormonal backdrop of the follicular phase
The follicular phase runs from the first day of menstruation until ovulation, roughly the first half of a typical cycle. Estrogen is low at the start and rises toward ovulation, while progesterone stays low. The popular framing is that this lower-progesterone, rising-estrogen environment may favor heavier loading and harder training, with some studies suggesting better recovery and force production, though the evidence is mixed and effect sizes are modest.
It is worth being clear that cycle-based periodization remains an area of active and inconsistent research; many well-controlled studies find small or no average performance differences across phases.
Putting it to practical use
If an individual feels stronger and recovers well in this window, it can be a sensible time to schedule heavier strength work or to push intensity, while tracking how she actually responds rather than assuming the textbook pattern. Symptoms during menstruation itself (fatigue, cramps) vary and may temper the early days.
This is general educational information, not medical advice. Cycle responses are highly individual, influenced by contraception and health conditions, so use personal tracking and consult a qualified professional for tailored guidance.