The menstrual cycle and performance: what no one tells young athletes

77% of elite athletes report their cycle affects their performance, and among adolescents one in four — up to six in ten — cuts back or avoids physical activity during their period. It isn't about willpower: it's a signal from the body that almost no one is taught to read. Here's the evidence, and where to start.

The menstrual cycle does affect sporting performance: 77% of elite athletes report it, and among adolescents up to six in ten reduce or avoid physical activity during their period. For too long, women's sport has been coached as if it were a smaller version of men's sport. But a teenage athlete's body changes — and with it, energy, recovery and mood shift across the cycle. The question isn't whether this happens: it's that almost no girl is given the tools to read it.

In short

  • 77% of elite athletes report their cycle has negatively affected performance (Jones et al., 2024) — an adult sample, mean age 28.
  • Among adolescents (10-18), between 25% and 61% avoid or reduce physical activity during their period (Harvey et al., 2025).
  • Only 6% of sport and exercise science studies are conducted on women only (Cowley et al., 2021).
  • Tracking your own signals over time helps you recognise them: monitoring is not diagnosing.

Does the cycle affect performance? What the data actually says

Yes — according to the large majority of athletes who live it. In a longitudinal study of 128 elite athletes in British Athletics' world-class programme, 77% reported their performance had been negatively affected by their cycle at some point during the study period (Jones et al., 2024).

Two honest caveats, because they matter. First: that sample has a mean age of 28. These are adult elite athletes, not thirteen-year-olds — the figure describes a real phenomenon in women's sport, but it is not a prevalence measured in adolescents. Second: it is self-reported. Far from being a flaw, that's precisely the point: what decides whether an athlete shows up to training is lived experience, not a lab value.

So what happens to 13- and 14-year-olds and their periods?

Here the evidence is newer and speaks the right language. A review of 86 studies across 33 countries in adolescents aged 10-18 found that the share of girls who avoid or reduce physical activity during menstruation ranges from 25.2% to 61.1%, depending on the population (Harvey et al., 2025). In one included study, 80.4% of girls with heavy bleeding had skipped PE.

And pain isn't the only reason. The same review notes that fear of leaking is a recurring concern, and that across several studies girls would rather sit out of an activity than risk embarrassment. It's a withdrawal nobody logs as an "injury", yet it costs training sessions exactly like one.

It's worth being precise about the other side too. A longitudinal study of 6,639 Australian adolescents found that menarche is associated with lower odds of taking part in individual sports (OR 0.74), but has no significant effect on team sports or moderate-to-vigorous physical activity (Gopalan et al., 2025). The cycle alone doesn't switch an athlete off. What does is the cycle lived in an environment that won't talk about it — a mechanism we covered in detail when writing about the silence between athlete and coach.

Why do we know so little about periods and sport?

Because the research looked elsewhere. The absence of simple answers is no accident. Across 5,261 sport and exercise science publications from 2014 to 2020, Cowley and colleagues found only 6% of studies were conducted on women only, and that female participants made up 34% of the 12.5 million subjects overall (Cowley et al., 2021, Invisible Sportswomen). Female athletes don't have fewer questions: they have less research behind them.

What can an athlete do about her cycle, starting today?

Four things, none of which requires permission or a diagnosis: observe your own signals over time, adapt the individual session instead of skipping it, talk to whoever coaches you, and tell what is physiological from what needs a professional.

Where BAB fits

BAB helps athletes recognise these signals privately, and gives coaches and clubs only aggregated, anonymous signals — never the cycle or individual health. Cycle phase, where shown, is an estimate and not a clinical value: we observe and flag, we don't diagnose. Because understanding your body should never cost you your privacy.

Sources

This article is for information only and does not constitute medical advice. If signals persist, speak to a healthcare professional.

Does the menstrual cycle really affect sports performance?

According to the large majority of athletes who live it, yes. In a longitudinal study of 128 elite British track and field athletes, 77% reported their performance had been negatively affected by their cycle at some point during the study period (Jones et al., 2024). Mind the age, though: that sample has a mean age of 28, so it describes adult elite athletes, not 13- and 14-year-olds. It is self-reported data — which is to say it captures lived experience, and lived experience is what decides whether an athlete turns up to training.

How many girls avoid sport when they have their period?

Far more than most people assume. A review of 86 studies across 33 countries in adolescents aged 10-18 found that the share of girls avoiding or reducing physical activity during menstruation ranges from 25.2% to 61.1% depending on the population studied (Harvey et al., 2025). Pain isn't the only reason: fear of leaking and embarrassment come up repeatedly.

Why do we know so little about the cycle and sport?

Because the research looked elsewhere. Across 5,261 sport and exercise science publications from 2014 to 2020, only 6% were conducted on women only, and female participants made up 34% of the total (Cowley et al., 2021). It isn't that the answers are hidden: for the most part they haven't been looked for yet.

Does menarche change participation in sport?

Less than commonly assumed, and not equally across sports. A longitudinal study of 6,639 Australian adolescents found that menarche was associated with lower odds of playing individual sports (OR 0.74), but with no significant effect on team sports or on overall moderate-to-vigorous physical activity (Gopalan et al., 2025). That matters because it deflates a cliché: a first period does not, by itself, switch an athlete off. What does is a cycle experienced in an environment that never mentions it — and if puberty arrives earlier than average, the risk of dropping out rises measurably (HR 1.68; Gallant et al., 2023).

Does the menstrual cycle increase injury risk?

On the most-studied question — anterior cruciate ligament rupture — the honest answer today is that we do not know. A systematic review of 21 studies and 68,758 participants rated the overall quality of evidence as 'very low' under GRADE: there is not enough evidence to link a cycle phase to higher risk (Herzberg et al., 2017). That does not mean the cycle is irrelevant; it means planning a girl's training around cycle phase for injury-prevention purposes has no scientific basis today. What does have one is consistency in preventive neuromuscular training.

Is training during your period harmful?

There is no evidence that physical activity during menstruation is harmful, and the largest meta-analysis on the topic — 78 studies and 1,193 participants — found the effect of cycle phase on performance to be «trivial», with evidence quality rated low under GRADE (McNulty et al., 2020). Two caveats: those participants are adult women aged 18-40, and equivalent data in adolescents simply do not exist. In practice the opposite of what you would expect happens: among adolescents aged 10-18, between 25.2% and 61.1% avoid or reduce physical activity during their period, often out of fear of leaking and embarrassment rather than pain (Harvey et al., 2025). If menstrual pain is severe enough to prevent normal activities, it isn't something to put up with: it should be taken to a healthcare professional.

Does the menstrual cycle make you lose strength?

Not to any meaningful degree, on the available data. The largest meta-analysis of the effect of cycle phase on performance — 78 studies, 1,193 adult women aged 18-40 — describes an effect of «trivial» magnitude, with evidence quality rated low under GRADE (McNulty et al., 2020); equivalent data in adolescents do not exist. The useful comparison is one of scale: the variation attributable to cycle phase is small, whereas resistance training in children and adolescents produces strength gains with an effect size of 1.12 (95% CI 0.9-1.3) that grows with maturation (Behringer et al., 2010). In practice, what a girl builds over months matters far more than how she feels in a single week.

Should training be adapted to the cycle phase?

The evidence does not currently support it, and for adolescents it simply doesn't exist. The largest meta-analysis on the effect of cycle phase on performance — 78 studies, 1,193 participants — found a «trivial» reduction in the early follicular phase compared with all other phases (ES 0.5 = -0.06; 95% CrI -0.16 to 0.04), with the quality of evidence rated low under GRADE (McNulty et al., 2020). Note the age: those participants are adult women aged 18-40. So the practical conclusion is twofold: there is no basis for periodising a 14-year-old's training around her cycle phase, but there are excellent reasons to ask how she is and adapt the individual session to what she reports.