Should You Work Out Differently on Your Period?What 78 Studies Found

Cycle-syncing apps and plans promise better workouts if you match training to your cycle. Researchers have tested the idea that performance changes across the month.

What 78 studies found

A 2020 review pooled 78 studies of women with regular cycles, mostly lab tests of strength and endurance at different points in the cycle.¹

• Performance might dip slightly in the early part of the cycle, which starts with your period, compared with other phases.¹
• The authors called the effect trivial, and the evidence quality low.¹
• Their conclusion: the results can’t support general rules for training by phase; watch your own response instead.¹

The review covered only women with regular cycles, not perimenopause or hormonal contraception, and it measured performance in lab tests, not a season of training.¹

Symptoms matter more than the calendar

A survey of 6,812 women who exercise, recruited through the Strava app, average age 38, asked about cycle symptoms:²

Symptom	Share reporting it
Mood changes or anxiety	90.6%2
Tiredness	86.2%2
Stomach cramps	84.2%2
Breast pain or tenderness	83.1%2

Women with more frequent symptoms were more likely to miss or change training, miss competitions and miss work or school.² Several authors worked for a company that sells a cycle-tracking app for athletes, and the women chose to answer.²

So both are true: the average lab dip is trivial, and a bad cramp day can still change your workout.¹²

Find your own pattern

1. For two cycles, jot each workout next to your period notes: what you did, and a word on how it felt.
2. Mark symptom days, not just period days: cramps, heavy flow, poor sleep, low mood.
3. Compare. You may find one hard day a month, or that the week you skip holds only one bad day.

If cramps are what stop you, regular exercise across the month has trial support: see does exercise help period cramps? If heavy bleeding is the problem, see how to know if your period is too heavy. Periods that stop while you train hard or eat less need a clinician’s look.

Try: “Two days a month my cramps and bleeding make running impossible. I’ve logged two cycles. What can I do about those two days?”

Period, Handled covers this in Chapter 10, “Work, Travel, Gym, Bed,” in a section called “Training on Your Period.” Its Period Scorecard sits next to your training notes for two cycles, so your own pattern answers the question the 78 studies couldn’t settle for you. See the book.