What Happens in the Body
The cycle runs in phases in which the hormonal situation changes considerably. Two effects matter for sport.
The first concerns performance. A study with female footballers showed poorer results in the Yo-Yo endurance test in the second half of the cycle than at other points. On top of that come highly individual symptoms — pain, fatigue, sleep quality.
The second concerns connective tissue. A higher oestrogen level reduces the stiffness of tendons and ligaments because collagen production declines. That is where the assumption comes from that injury risk is elevated around ovulation.
What the Research Shows — and What It Does Not
Honesty matters here more than a neat rule.
There are solid indications that cycle phases relate to performance and injury risk. A study of international players found that around twenty per cent of all injuries occurred when the player was "overdue" — when the period started later than in a regular cycle.
What does not exist is a proven model for cycle-based training that could be imposed on a squad. The evidence is inconsistent, individual differences are large, and many studies work with small samples.
For you as a coach that means: the topic is real enough to take seriously and too uncertain to turn into a rigid training plan.
The Point That Actually Concerns Coaches
If you take one thing from this article, take this: the elevated injury risk is the most practically relevant finding.
Football carries one of the highest ACL injury rates of any sport, and female players are affected considerably more often than male players. If hormonal phases influence that risk further, it is not a marginal topic.
The practical consequence, however, is not to withdraw players in certain phases. It is that the basic work is in place: jumping and landing technique, core stability, Nordic hamstring, a complete warm-up programme. Those components work regardless of the cycle and are the only part you can directly influence. The overview is in the guide to injury prevention, and specifically on the knee in preventing knee injuries.
What You Can Actually Do
- Adjust the load when a player raises it. Not by calendar, but by feedback.
- Anchor prevention work firmly. Every session, not only when there is time left.
- Create a feedback route that works without explanation. Many clubs use a simple wellbeing scale — whoever feels bad does not have to say why.
- Do not comment on absence. Nobody missing because of symptoms should have to justify it.
- Refer to professionals. Severe symptoms or an absent period belong with a doctor, not with a coach's judgement.
What You Should Not Do
- Do not collect cycle data. That is health data. In amateur football a coach has no business with it.
- Do not draw conclusions about performance. A weak session is not a diagnosis.
- Do not raise it in front of the squad. Neither jokingly nor with concern.
- No advice on contraception or medication. That is medical territory, without exception.
How to Raise the Subject
The most common mistake is turning it into a conversation. Better is a single, matter-of-fact statement at the start of the season that opens a door without creating attention:
That is all it takes. The sentence does two things: it names no cause and demands no justification.
If you are a male coach and feel uncertain, the best solution is structural anyway: a woman on the support staff whom players can approach. What else matters in coaching girls is covered in the article on coaching girls' football.
As of August 2026. This article does not replace medical advice.
5 Takeaways for Coaches
- Take it seriously without overstating it. The indications are real, a ready-made training model is not.
- The biggest lever is prevention. Landing technique, core, Nordic hamstring — independent of the cycle.
- Create feedback without a duty to explain. That is the whole core of it.
- Do not collect health data. Not your role, not your responsibility.
- One statement per season is enough. After that, act rather than talk.