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Exercise and Periods: Why More Research Is Needed

Author: Forth

February 22, 2021

Female health

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As more and more women take up exercise, we look at how much we really understand about female hormones and the impact the menstrual cycle has on women in sport and those who exercise regularly.

Women & Exercise

A recent study has found that the number of women participating in sports or physical activity at least twice a month has increased from 17.3 in 2016 to 17.8 in 2020, showing a slow but steady increase.

A Government report on a study into physical activity found that 61.5% of women over the age of 16 were physically active. This is compared to 65.3% of men.

Yet, historically, little research has been carried out to understand how women’s hormones and their monthly menstrual cycle impact their exercise performance. The bulk of exercise research is based on men with very few studies exploring the specific needs of physically active women in relation to their hormone health (1).

Female Hormones & Exercise

We know that exercise plays an important role in all aspects of health – physically, mentally, and socially (2). However, the fluctuations in female hormones during the menstrual cycle can make it more challenging for women as hormones impact exercise performance and as well as overall wellbeing.

Nearly half of female runners in a large survey reported their menstrual cycle negatively impacted exercise performance (3).

Working Out On Your Period

Each phase of the menstrual cycle is accompanied by changes in a woman’s four main hormones – follicular stimulating hormones, luteinising hormones, oestrogen, and progesterone.  During each phase, a woman will experience different symptoms to varying degrees, from low energy, sleep disturbance, to mood changes and changes in appetite (4).

Let’s take a look at each phase in the menstrual cycle and how each phase can impact working out during your period.

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Menstruation takes place on days 1 to 5 and is when the body sheds the thickened lining of the uterus. Oestrogen and progesterone levels are at their lowest.  There is some limited research suggesting the body utilises carbohydrates (glycogen) stores more efficiently and may help to reduce appetite. This means that women may find they have better endurance and performance in high intensity cardiovascular or strength training than they do in the luteal phase.

Follicular Phase (days 1-14):

The follicular phase happens on days 1 to 14, starting at the same time as menstruation and ends with ovulation. In the follicular phase, the ovaries are stimulated by follicular stimulating hormone (FSH) to produce follicles, with one maturing into an egg. Follicle growth also raises oestrogen and luteinising hormone (LH). Levels of FSH and LH peak prior to ovulation, and oestrogen is also highest in the follicular phase. Some research suggests that during the follicle phase women should increase their intake of carbohydrates and protein. The follicular phase could be a good time to focus on fitness.

Ovulation (days 14-15):

Ovulation is when the mature egg is released and takes place mid cycle, days 14 to 15.

Luteal Phase (days 14-28):

The luteal phase happens around days 14 to 28 and is when the follicle that the egg was released from remains on the ovary. This becomes the corpus luteum and releases progesterone and oestrogen. Progesterone levels are at their peak in this phase and thicken the lining of the uterus allowing a fertilised egg to implant. When pregnancy does not take place, the corpus luteum degenerates, progesterone levels drop, and menstruation begins.  

Some studies suggest that during this phase women should focus on increasing their intake of protein due to progesterone requiring more protein biosynthesis to thicken endometrial lining (the innermost lining of the uterus) and prepare the body for possible pregnancy (5). The body will also require a consistent intake of complex carbohydrate to meet the demands from increased metabolic rate, driven by progesterone during this luteal phase.

It is important to note that these phases are not the same for all women.

Gender Gap In Research

Despite the limited studies, we do not yet know enough about how a woman’s menstrual cycle impacts her ability to exercise and perform at her best. We urgently need evidence-based advice to help women manage the complexities of female hormone cycles (6). Continuing to apply the male blueprint for exercise, nutrition and recovery to females is not the solution.

We need the evidence to answer some simple, yet important questions:

  • How does the menstrual cycle impact exercise performance?
  • What is the best sort of exercise strategies for various phases of the menstrual cycle?

The reason for this gap in evidence is that much of the research and application of sports and exercise science is based on male physiology (7). In fact, research often actively avoids including females as their hormone networks are deemed too complicated. Yet there are differences in physiological responses to exercise between men and women, most likely due to ovarian hormones as these distinguish between the biological sex of male and female (8).

Despite it being relatively straight forward, in theory, to show how oestrogen and progesterone impact exercise performance during different phases of the menstrual cycle; studies have failed to identify a cause-and-effect correlation.

Numerous studies looking at the effects of the menstrual cycle on a variety of exercise elements, very surprisingly, found no significant effects of menstrual phases on exercise performance. In the meantime, this uncertainty and confusion has resulted in misinformation and varying trends around women’s sports performance in relation to their hormones.

How could it be that no unifying conclusions were found from all these studies? Well, that’s simple to answer, each woman is an individual.

Each individual woman’s female hormones will not necessarily fluctuate in a standard textbook way in terms of timing of hormone release or hormone concentrations. So, attempting to compare women at exactly identical points in the cycle is impossible.

This is precisely the conclusion that recent years of research have come to. The conflicting results were because the timing of hormone fluctuation was different in each woman, in each study.

Helping Women Perform Better In Sport

In order to address this gender data gap in sports performance, Forth conducted research with professional female athletes and gave the participants information that provided a greater understanding of how their unique cycles related to their performance.

Woman doing long jump

This has led to the development of a unique and personalised female hormone blood test, MyFORM™, that maps the four main hormones – FSH, LH, oestrogen, and progesterone – for the whole of the menstrual cycle.  This data coupled with information on symptoms will enable a tailored report to be produced that offers personalised advice for that woman – treating her as an individual.

“Treat women as individuals and no statistics” as stated by the Vice President of the Royal College of Obstetrics and Gynaecologists (9)

Unlike period tracking apps, MyFORM™ does not use averages to predict a woman’s next period, instead, it provides a personalised view of an individual woman’s hormones to predict her next menstrual cycle and overall hormone health.

Using this insight will ultimately enable women to achieve their full potential, in terms of sports performance as well as overall wellbeing, regardless of their age or chosen form of exercise.

In Conclusion

Many women are impacted by their menstrual cycle when it comes to exercise and sports performance, as well as general wellbeing.  We know this, the premenstrual symptoms women experience to varying degrees can have a big impact on everyday life, let alone exercise.

Some of the advice about doing certain types of exercise or eating certain foods are helpful for some women. However, it must be reinstated that this will entirely depend on your own, personal female hormone variations over a menstrual cycle and your personal biological response to these hormones.

Read Next: ‘The Role Of Hormones In Women’s Health’

View More Female Health Articles>>

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Article references

  1. Keay N, “Of Mice and Men” British Journal of Sports Medicine 2019
  2. Keay N, Lifestyle Choices for optimising health: exercise, nutrition, sleep British Journal of Sports Medicine 2017
  3. Bruinvels G, Burden R, Brown N, et al The prevalence and impact of heavy menstrual bleeding (menorrhagia) in elite and non-elite athletes PLoS ONE 2016;11:e0149881
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7381001/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6167362/
  6. Bruinvels G, Burden RJ, McGregor AJ et al Sport, exercise and the menstrual cycle: where is the research? British Journal of Sports Medicine 2017;51:487-488
  7. Costello JT, Bieuzen F, Bleakley CM Where are all the female participants in Sports and Exercise Medicine research? Eur J Sport Sci 2014;14:847–51
  8. Sheel AW Sex differences in the physiology of exercise: an integrative perspective. Exp Physiol 2016;101:211–2
  9. Rymer J, Brian, K, Regan L. HRT and breast cancer risk. BMJ Editorial 2019. dx.doi. org/10.1136/bmj.l5928

This information has been medically reviewed by Dr Thom Phillips

Thom works in NHS general practice and has a decade of experience working in both male and female elite sport. He has a background in exercise physiology and has published research into fatigue biomarkers.

Dr Thom Phillips

Dr Thom Phillips

Head of clinical services