The short answer
There's nothing against training during your period. But there's also nothing against going lighter on a day with cramps and poor sleep. Either way, it's a decision about the day, not about the cycle.
What the studies say about performance
A 2025 systematic review included only studies in which hormones were actually measured. For the days of bleeding, some studies found slightly lower endurance or peak performance, others didn't; maximal and explosive strength stayed largely the same. A 2026 meta-analysis of elite athletes found no significant difference in maximal oxygen uptake, only a small, non-significant downward trend. The older 2020 meta-analysis had already concluded “trivial at most”, with low study quality.
A 2026 study followed trained women over two training blocks: cycle phase changed strength performance only minimally, while motivation on the day was clearly linked to it. An average from studies therefore tells you little about what your Tuesday will look like.
What you can sensibly adjust
Instead of pausing or pushing through regardless, adjust individual settings on bad days:
- Intensity before volume. Reduce weight or pace rather than the whole session. You still train, just one notch quieter.
- Postpone max attempts. You don't need a new personal best on a day with cramps. It will still be there later.
- Warm up longer. If everything feels stiff, a longer warm-up costs ten minutes and saves the session.
- Skip lying on your front and heavy abdominal pressure if it's uncomfortable. There's an alternative for practically every exercise.
- Eat and drink as usual. Eating less because you feel bloated makes the day worse, not better.
We often hear that exercise relieves period pain – with the sources we cite here, we can't show it. If light cardio feels good to you, that's reason enough to do it; we don't turn it into a promise.
If the bleeding is heavy
Heavy periods are more than an inconvenience: they are one reason why menstruating athletes are more often affected by iron deficiency. Tiredness that drags on for weeks and performance that drops for no reason therefore don't belong in the “it's just my period” category, but in the lab. How to go about it is in our article on iron, periods and exercise.
What Rhythmus does with this
The app doesn't prescribe a fixed programme for the days of bleeding. What counts is the daily energy check-in: if it's low, Rhythmus suggests a lighter session – regardless of which cycle day it is. Why we built it this way instead of a phase plan is in our article on the evidence for cycle-based training.