21–35 days is the normal range. About 13% land on 28.
Let’s kill a myth right away: the “textbook” 28-day cycle is basically a unicorn. Only about 13% of women actually have one. The rest of us are somewhere in a very normal range of 21 to 35 days, and no, that doesn’t mean your body is broken, confused, or bad at math.
A cycle has two main acts, separated by one very short, very important event: ovulation.
Follicular: oestrogen rises. Energy often lifts, but not for everyone.
Act one: the follicular phase (roughly 10 to 22 days). It starts on day one of your period. Oestrogen slowly climbs. Many athletes feel their mood, motivation and concentration pick up here. Many not all. Your mileage may vary, and that’s not a defect, that’s just biology being biology.
Ovulation is the landmark. Counting days is not.
The plot twist: ovulation (about 1 day). A hormonal signal tells the ovary to release an egg. Some women feel a small twinge, a mood shift, or nothing whatsoever. Ovulation isn’t just a reproductive detail, it’s the single most reliable landmark for knowing which half of your cycle you’re actually in. Way more useful than counting days from your last period like it’s a countdown timer.
Act two: the luteal phase (roughly 9 to 16 days). Progesterone takes over. It can raise your body temperature slightly, calm your nervous system, and, for some, bring along the lovely bonus pack of premenstrual symptoms. And by “some,” we mean there are over 150 documented PMS symptoms out there. No, you will not get all of them.
Why does any of this matter for training? Because understanding your own pattern is the first step to working with your body instead of being ambushed by it every month. Not because you need a PhD in endocrinology, just enough to stop being surprised by your own hormones.
A regular cycle is a sign of enough energy to go around.
A regular cycle, by the way, is also a quiet health check-in: it usually means your body has enough resources to keep all its systems running. That’s worth knowing before we even talk about performance.