Cycle phase calculator / Cycle day 31

Cycle day 31: what phase am I in?

On a 32-day cycle, day 31 is usually the luteal phase (late luteal, the week before your period). On a cycle of 30 days or shorter, your next period would usually have started by now.

Day 31 is late luteal on a 32 to 35 day cycle. A cycle that runs a few days longer than usual is common after stress, illness, travel or a hard training block.

Day 31 across different cycle lengths

Assumes a 5-day period and a 14-day luteal phase, the same model the Phaes app uses. Your own cycle can vary by a few days from month to month.

What is happening in your body

In the last week before your period, estrogen and progesterone both fall. This drop is linked to premenstrual symptoms: bloating, sore breasts, poor sleep, low mood or irritability.

Perceived effort runs higher. A heavy-legged run here is not lost fitness.

How to train on day 31

Running

Lower the intensity ceiling. Steady, easy aerobic running suits this phase, and a full rest day here pays off because recovery takes a little longer.

Strength

Hold steady. Phaes keeps strength at maintenance through the luteal phase rather than chasing new highs.

Fuel

Hydrate more (the higher temperature costs fluid), and keep protein steady. Appetite often rises a little, which is normal.

Treat this as a starting point. A meta-analysis of 78 studies found that cycle phase has at most a trivial effect on performance on average, with big differences between women (McNulty et al., 2020). How you slept and how you feel today should win.

If your cycles are changing

In perimenopause cycles get shorter, then longer and less predictable, and ovulation does not happen every month, so a day number stops telling you much about your hormones. The training answer changes too: short sprints over long slow miles, lifting heavy, easy days that are genuinely easy, one full rest day a week and a reset week every fourth week. Take the perimenopause quiz if you are not sure where you are.

Questions women ask about day 31

What phase is day 31 of my cycle?

On a 32-day cycle, day 31 is usually the luteal phase (late luteal, the week before your period). On a cycle of 30 days or shorter, your next period would usually have started by now.

Should I work out on day 31 of my cycle?

Yes, if you feel up to it. Lower the intensity ceiling. Steady, easy aerobic running suits this phase, and a full rest day here pays off because recovery takes a little longer.

How should I lift weights on cycle day 31?

Hold steady. Phaes keeps strength at maintenance through the luteal phase rather than chasing new highs.