Period Performance
Your cycle is training data.
One month, four phases, and a body that changes what it needs at every stage. Turn the dial to any day to see what's happening inside, what you might feel, and how to train, fuel and recover around it.
Built for athletes, coaches and anyone who moves
Not medical advice — your cycle is yours
Day 1 is the first day of real bleeding. Drag the ring, tap a day, or use the arrow keys.
The hormones underneath it
Two hormones do most of the talking
Oestrogen builds through the first half and spikes just before the egg is released. Progesterone only shows up afterwards — and it's the one that nudges your temperature, your heart rate and how hard a familiar session feels.
Where to put the hard work
A load map for the month
A starting point, not a rulebook. Longer bars mean most people tolerate that work well in that phase. If your own data says otherwise, your data wins.
Worth a conversation with a professional
Signals your body is asking for help
Your period stopped or went irregular
A missing period is not a sign that training is going well. It's usually a sign that energy in isn't matching energy out, and over time that shows up in bone density, iron and injury rates. Talk to a sports physician early rather than waiting it out.
Bleeding heavy enough to change your day
Soaking through protection hourly, passing large clots, or needing to plan sessions around flow is worth investigating. Heavy loss is a common and very fixable cause of low iron and flat training.
Pain that stops you training
Cramps that respond to movement, heat and over-the-counter relief are normal. Pain that removes you from sessions, or that shows up outside your period, deserves a proper look — conditions like endometriosis are routinely missed for years.
You're on hormonal contraception
The pill, hormonal IUDs and implants change this picture completely — many suppress the natural hormone swing altogether. The phase advice here won't map to your month, so track symptoms and performance directly instead.
Clearing the air
Four things people still get wrong
Athletes have set world records while bleeding. For many people gentle-to-hard movement eases cramps rather than worsening them. Adjust by how you feel that day, not by the date.
Anywhere from 21 to 35 days is typical, and the first half is what varies. The stretch after ovulation stays close to 14 days for most people, which is why this page works backwards from there.
The same data tells you when sleep gets patchy, when heat hits harder, when your warm-up needs more time, and when you're primed for a heavy block.
It isn't. Most cycle-and-performance studies are small, and the average effect on performance is smaller than the difference between individuals. Which is exactly why three months of your own notes beat any chart — including this one.
The dial becomes an app.
We're building Period Performance into something that learns your cycle: log your flow, sleep, symptoms and sessions, and get the read on your day instead of the textbook's. Leave an email and we'll bring you in for early testing.
No spam, no selling your data. Ever.
This page is general education, not medical advice. If something feels wrong in your cycle, see a clinician who takes it seriously.