How do periods effect women’s sport performance?

Until recently, I have never noticed a difference in my sports performance when I am on my period. During my most recent cycle (when I was menstruating), I was running an interval session, and it felt particularly difficult. I felt lethargic from cramps. I couldn’t run as I wanted to. I couldn’t put the effort in that I wanted to. My body said no. I was frustrated, why was it so difficult to run? The tampon adverts make exercising on your period look blissful. It’s not.

In school, sports lessons were segregated into boys and girls. Women taught the girls and men taught the boys. But despite this segregation, there was no specialised curriculum for either sex. We weren’t taught about being a woman in sport, how the female body is different to the male body and its effect on our sporting ability, nor how periods might affect our performance. I’m only just learning this now. As I am experiencing it. Periods do affect sporting performance, but how? Why?

The menstrual cycle

A women’s menstrual cycle lasts 28 days, on average, but can range from 21 up to 40 days. It is a continuous cycle throughout her fertile life – from her first period to menopause. The cycle is controlled by hormones which cause the development and release of an egg, and prime the uterine lining to thicken in preparation for the implantation of an embryo. However, if an egg isn’t fertilised and pregnancy isn’t achieved, the uterine lining sheds which we know as our period.

There are two main phases of the menstrual cycle: the follicular and the luteal phase. They are primarily defined by differing hormone levels.

Follicular phase

Day one. Menses marks the start of the cycle. Follicle-stimulating hormone (FSH) is released from the pituitary gland stimulating the ovaries to produce fluid-filled sacs (follicles) which eggs can mature in. A single follicle becomes dominant and produces a mature egg which is eventually released at ovulation. The dominant follicle releases oestrogen. Increased oestrogen levels cause the pituitary gland to release less FSH and more luteinising hormone (LH). As LH levels peak, ovulation is triggered at day 14 and the second half of the cycle begins.

Luteal phase

Day 15. Oestrogen and LH levels have dropped, and progesterone levels are increasing. Progesterone helps the lining of the uterus to thicken, creating an optimum environment for a fertilised egg to implant into. If you do not become pregnant during this phase, hormone levels decline, the uterine lining sheds and the cycle restarts with menstruation.

Most women will be familiar with the cycle and the symptoms it presents itself with. Joint and muscle pain, headaches, cramps, fatigue and poorer sleep quality. Anxiety, bloating, mood swings and tender breasts. Ninety percent of women present with these symptoms, on a monthly basis, yet their effect on sporting performance is rarely spoken of.

Sports performance

As our hormones vary across the menstrual cycle, our body is responds differently to exercise across the month. During the follicular phase of the cycle, when hormone levels are low, the body is optimised to access stored carbohydrates. Therefore, this period is ideal for high-intensity training; building and maintaining muscle is easier. Once we enter the luteal phase hormone levels have increased and muscle building capacity has decreased. Lower intensity training with longer recovery time is favoured. The body requires more water because the higher levels of hormones put your body at greater risk of dehydration. More food is also needed as fuel because stored carbohydrates are less accessible.

Using this knowledge, women can take control of their cycle. Designing their training plan efficiently to improve their athletic performance and prevent injury. Yet, the scheduling of races and competitions is out of our control.

Female athletes have reported dips in their consistent performances at competitions being due to “girls’ stuff”. And whilst this ‘stuff’ isn’t guaranteed to affect your performance - Paula Radcliffe set the marathon world record on her period – there is no apparent solution for those who do feel an impact.

More research into the effect of the menstrual cycle has been called for. Women are underrepresented in research studies, resulting in a significant data gap. This is partly due to their fluctuating hormone levels, meaning their variable results have been treated as outliers. As a result, there is a limited ability to apply an evidence-informed approach to female coaching/training. Improving research into female sports performance is the obvious long-term solution to determining the impact of periods. But research takes time. Is there a faster, short-term solution?

Some athletes use the contraceptive pill to control when their period occurs, or to completely stop them, which can resolve the issue of races and periods coinciding. Yet, the pills dose of oestrogen and progesterone can induce another set of symptoms and may impact performance as well – however research is inconsistent.

Educating women on period and sports management would also be a simple solution. However, we have already identified there is limited research in this field, thus limiting the education that can be given. Nevertheless, I do believe schools should be more accountable for teaching girls about their menstrual cycle.

The menstrual cycle is extremely individual. All women have a different experience, making it difficult to quantify how it effects sporting performance. Difficulty, however, is not a justifiable reason for the lack of research performed in the field. To make a real difference for female athletes we must move away from our reliance on short-term solutions and join the debate about menstruation in sport. Hopefully, more noise being created will extend to more clinical research and therefore solutions to the issues women face in sport.