How the menstrual cycle can make or break an athlete’s performance

As soccer’s Women’s Asian Cup continues in Australia, much analysis will inevitably focus on the physical: the speed of Mary Fowler, the power of Sarina Bolden, the endurance of Yui Hasegawa and Ellie Carpenter.

However, in high-pressure environments, those who think the quickest and most creatively can have just as much impact as those who run the fastest.

This brings us to a crucial, under-researched frontier in sports science: the influence of women’s sex hormones that regulate processes such as the menstrual cycle, and what the central nervous system does for athletes.

My recent study analysed previous and current research that suggests the menstrual cycle can play a role in performance, while also drawing attention to the fact there is still so much we do not know.

The power of the brain

To produce their skills and make the right decisions, athletes need effective interaction between key body systems such as the nervous, endocrine (hormonal) and muscular systems.

The nervous system is primarily the command and communication system of the body and includes the brain, spinal cord and motor neurons.

A key function is to collect information that can then be used to make decisions (in the brain), then initiate and execute movements.

The brain is able to command tasks through regulating processes such as attention, memory, judgement and creativity. These processes also underpin learning, which ultimately allows us to perform.

The endocrine system meanwhile produces and manages hormones in the body, which also helps with communication. For example, sex hormones (oestrogen and progestrone) act as neurotransmitters and help regulate brain activity.

Oestrogen and progesterone fluctuate dynamically across the menstrual cycle, with low levels during week one of menstruation and a steady rise in week two. Oestrogen peaks just before ovulation (around the middle of cycle), while progesterone reaches its highest levels after ovulation.

Both hormones return to low levels in the days leading to the next bleeding phase.

But how is this relevant to sport performance? Let’s dig a little deeper.

How hormones can affect athletic performance

Consider your favourite Matildas team member: she is skilled, tenacious and renowned not only for her athleticism but her tactical nous.

She must read the play and either attack, defend, or set up play for others. That involves lots of thinking and making decisions under pressure.

Now imagine if a highly skilled and consistent athlete is a little off their game. Any number of factors could be at play, one of which is hormone fluctuations associated with the menstrual cycle.

During different phases of the menstrual cycle, hormones rise or dip, which can mean the brain may or may not be getting enough hormones to work efficiently.

A dip in hormone levels may impact performance positively or negatively: it may mean you are a little calmer, or you react a little slower. Likewise higher levels (around ovulation) may lead to increased errors, or more risk-taking.

But here’s the kicker – sometimes hormone fluctuations leave some women performing even better at certain stages of their cycle than they would anticipate.

Some emerging research has found women may be quicker to react during the bleeding (menstrual) phase, or their spatial awareness may be better during the first half of the menstrual cycle.

This knowledge is crucial in sport because it might be the difference between winning and losing.

Importantly, for athletes who experience changes in cognition due to hormone fluctuations or symptoms (not everyone does), it can lead to making a decision too late – potentially conceding a goal, losing possession, or moving in a way that causes an injury.

It must be noted any influence of menstrual phases on athletic performance is highly individualised.

Other factors such as sleep, recovery, fatigue or perceived fatigue and even altitude can also play a role, so it’s important to note this is only one factor when it comes to performance.

It is also important to consider menstrual symptom management which can include pain, heavy bleeding, bloating, breast soreness and nausea – all of which are particularly difficult on training and competition days.

Athletes must manage the practical aspects of menstruating which may include carrying extra pain medication, heat packs, or highly supportive bras. Moreover, they must consider whether they have comfortable and effective ways to manage bleeding, and what facilities are available.

Some athletes may use hormonal contraception to reduce symptoms or skip periods and time bleeding onset.

Crucially, research indicates many athletes using hormone contraception report negative side effects such as mood swings and weight gain.

This emerging scientific area is beautifully complex and one we need to understand better if we truly want women to thrive and reach their full potential in sport.

Practical advice for athletes and coaches

As we close the knowledge gap, there is still much we can do in the field.

First, encourage athletes to track their menstrual cycle (preferably on paper so they can decide how this information is used).

Athletes should understand sensitive medical information is theirs alone to share. Coaches should never use this information to bench an athlete, for example.

Tracking cycles allows women to see patterns – they can predict possible dips or highs in performance and implement mitigation strategies. Strategies may include athletes performing a longer or more specialised warm-up, or even resting a little more.

To help athletes mentally prepare for a game, and when they know hormone fluctuations may leave them a little distracted, coaches could also implement extra cognitive motor drills (tasks that make them think and move).

This might include small-sided games, reaction time tasks and fun, fast decision drills.

So as you gear up for the Women’s Asian Cup finals, look beyond the physical. Be curious about what drives these athletes’ performance and what may or may not influence their form.

Above all, appreciate the complexity of being an athlete in women’s sport.