Despite working in the realm of ‘women’s health’ for many years of my life, I recently realised that this wasn’t something I’d ever written, vlogged or even talked about much on my social media. As something that affects so many of us, I thought it would be a good idea to rectify this, and hopefully shine some light on how menstrual cycles can affect training, what it means to lose your period and how we can take care of our bodies the best we can, while achieving the fitness goals we set out to achieve.

To give a little background, I worked at the Royal College of Obstetricians and Gynaecologists as a press officer and social media manager for over a year after I left university. I then went on to run the social media accounts for Freda, a sustainable period products brand that helps reduce period poverty here in the UK with every purchase. So, I know a thing or two about periods and the taboos that surround them, but for some reason have never spoken about it openly. Many thanks to Renee Mcgregor, a sports dietician specialising in overtraining and athlete health, for her help talking me through the complexities of the human body. Give her a follow, and check out her ebook for more information on this topic. 

Do periods affect training?

Historically, scientific research on women has been limited, thanks in no small part to the fact that periods are considered a ‘confounding factor’ when it comes to medical trials. In addition, the difficulty of finding a large enough cohort of people whose cycles match up adds an extra layer of complexity in organising scientific trials, limiting the number that have been carried out. However, more recently there have been several studies that show that changing hormones can affect both how we feel, as well as our performance. For years, scientists and coaches have worked on the assumption that biological females are essentially the same as males, just with different reproductive organs, but when it comes to training and the effect of hormones, we see that this isn’t true. 

Anyone who has periods will know how moods, energy and motivation vary throughout their cycle, although you might not know why this is. FitrWoman, an app designed to assist training planning around the menstrual cycle, explains how training can be affected by fluctuating hormones throughout the four-phase cycle. It is important to remember that while the average length of a cycle is 28 days, for someone else it may be more or less – what is important is knowing what is normal for you. 

“Starting with periods (phase 1), this is when women can experience a high amount of symptoms (e.g. back pain, cramps, fatigue) which can impact how you are feeling and therefore may impact exercise training/performance. Anecdotally, lots of the sportswomen we come across also cite that heavy bleeding has either caused them to change the way their train or miss training altogether, so this is definitely something key that we want to address. Things like moon cups can be game changers for some, and really heavy bleeders may want to be referred to a gynaecologist.

“After menstruation, levels of the sex hormones oestrogen start to increase (in Phase 2), and this can often be a good time to progress in training and just crack on. There is a little evidence to suggest that you can actually capitalise on strength training a bit more in this phase, likely due to the effect that oestrogen has on muscle anabolism/muscle protein synthesis.

“Oestrogen levels rise to a peak just before ovulation, and then progesterone levels start to increase (in Phase 3). Both of these hormones travel in the circulation and therefore can affect many physiological systems, not just the reproductive system. Progesterone often causes a small increase (by about 0.3-0.5 degrees C) in core body temperature and may cause an elevated heart rate, both which may affect exercise in the heat. Phase 3 can also be when sleep disturbances occur, and so without the right strategies in place, this can affect training. 

“Towards the end of Phase 3, and in Phase 4, pre-menstrual symptoms are likely to occur, and this is where a lot of our work with our Female Athlete Programme is focused on. Whilst there is little evidence that exercise performance is affected by menstrual cycle phase, this is with a slight caveat of: ‘given that symptoms are managed’. Research has found that many active women say their menstrual cycle has negatively impacted their performance, and it is often during this phase. The sharp drop in oestrogen and progesterone concentrations could result in delayed recovery, increased cravings, increased fatigue, pain, mood swings and poor motivation through a multitude of mechanisms. However, it’s not all doom and gloom! It’s just about learning what your individual menstrual cycle means for you and being savvy about how to manage any symptoms you experience”. 

Esther Goldsmith, sports scientist at FitrWoman

All this to say: where you are in your cycle really can affect how you feel during training, but provided it’s not too hot, and provided you are able to manage symptoms, there’s little reason why your overall performance would be affected by your cycle. Having said that, it is important to note that if you are struggling, it might be worth switching round your routine in order to capitalise on days that you feel stronger. Tracking your cycle might help explain days where effort felt higher, or days you really aced training. I generally think that if I can workout on a day where I feel very ‘meh’, I can workout any day, and it’ll feel so much easier!  It is important not to beat yourself up for a ‘bad’ training session – every session serves a purpose – and while your cycle may not be an excuse for a bad session, it may well be a reason. 

Should you exercise on your period?

We are all unique, and as with so many health-focussed topics, the answer to this depends on personal preference and how you feel, as mentioned above. For many people, exercising during their period alleviates symptoms such as cramps and low moods, meaning that training is a great way to manage these things. For others, however, training can feel impossible, or at least immensely unpleasant. Dr Vanessa Mackay, spokesperson for the Royal College of Obstetricians and Gynaecologists, recommends attempting light exercise during your period. 

“Women may not feel like exercising during a painful period, but keeping active can help relieve period pain and discomfort. Woman are encouraged to try low impact exercises such as swimming, walking or cycling.

“Exercise can also help to regulate menstruation. If women are stressed, their menstrual cycle can become longer or shorter, their periods may stop altogether, or they might become more painful.  Regular exercise, such as running, swimming and yoga, can help women to relax.

“If women experience severe period pain, or their normal pattern of periods change, they should speak to their GP.”

What’s important to note is that while it may assumed to be ‘normal’, being bedbound during your period is not something you should just ‘have to live with’, and if you are experiencing extreme discomfort and pain, you should visit a gynaecologist or doctor. Sadly, understanding around these issues is still pretty poor – it takes on average 7.5 years for someone to be diagnosed with endometriosis, for example – but if you feel something is wrong, please insist on seeing your doctor and getting a diagnosis. Similarly, if your normal pattern changes, e.g. you experience very heavy bleeding suddenly or lots of pain, speak to your GP, or even better a gynaecologist or endocrinologist. You should not have to suffer in silence. 

Fuelling also may need to change around your cycle, especially in endurance sports. As hormones fluctuate, the need for protein and carbohydrates varies, as well as micronutrients, such as iron. Iron is especially important during and after your period, as iron is lost when you bleed. During phase 1 and 2 (the first half of your cycle), more carbohydrates are required, as the body is burning more fat. This is especially important in endurance training, and long fasted sessions should be avoided, as they place unnecessary stress on the body. During the second half of the cycle (phases 3 and 4), progesterone levels are higher, as is the BMR (basal metabolic rate), meaning that cravings are higher, but also that the body really does need more food. Energy expenditure can increase by 2-11% during this half. Here you should consume more healthy fats and have a regular intake of protein. A general rule of thumb is to make sure you’re getting in enough carbohydrates, have a regular intake of protein and listen to your body – it may be telling you exactly what you need! 

For what it’s worth, I do not consciously change my exercise routine around my period. However, I do experience very low energy at certain times of the month (not every month – I’m still trying to figure out when, exactly) and often change around my routine to allow for extra food and rest on these days. I would never head out for a long run on a day when I feel exhausted to the point of needing a midday nap, and might instead take a walk or fit in a stretching session (both of which are useful parts of training, just less intense). Having said that, I also find a short (5-8k) run helps with PMS symptoms more than anything else, including painkillers! They’re definitely not my best runs, but for cramps and low mood, nothing beats an easy run for me.

TL;DR

• Your hormones may affect perceived effort in training depending at the point you are in your cycle, especially in endurance training and in the heat.
• Every woman is different: while some may feel no change, others may experience severe symptoms that affect how they are able to train each month. If you feel unable to complete normal tasks, consider visiting an endocrinologist or gynaecologist.  
• Low intensity exercise may help reduce pre-menstrual symptoms and regular exercise is recommended to keep the body healthy. 
• Your hormones can be capitalised upon to make the most out of your training – it’s not all bad news! Some parts of the cycle may be better for muscle growth, and training when you don’t feel your best can make other training sessions and races feel that much easier. 
• Be kind to your body! Don’t beat yourself up about a bad training session. Ensure you are getting enough rest days and taking on enough fuel and you’ll be back on track in no time. 
• Don’t forget that carbs are a necessary part of training, and especially required in the first half of your cycle. Make sure you have a good intake of protein and healthy fats. 
• Periods and hormones are healthy. It is impossible to be optimal if these hormones are out of whack e.g. if you lose your period due to overtraining. More on this later!

I hope this helps you and answers some of your questions about training at different parts of the cycle. Many thanks to Fitr Women for explaining the different phases and how these may affect training. If you are not sure how your cycle affects you, it may be worth tracking it with an app or on your calendar. While it may not be an ‘excuse’, it can often be reassuring to know why a particular session felt so hard, and know the days you will be able to make the most out of your training. 

What I’ve learned from this research is that everyone is unique, and what works for one person may not work for another. However, it does seem to be the case that when everything is functioning well, the menstrual cycle can be beneficial for capitalising on training and optimising performance. It’s sad to see so many women experiencing debilitating symptoms every month and assuming this is normal. I hope this encourages more people to know what they are capable of, and others to seek help if they feel something is off. 

If you’d like to learn more about this topic, these podcasts were particularly helpful for me:

• Trained: Georgie Bruinvels – Using the Menstrual Cycle as a Personal Trainer
• The Food Medic: Women Are Not Small Men
• The Food Medic: Inferior: How Science Got Women Wrong
• The Bad Boy Running Podcast: Race Nutrition with Renee Mcgregor

If you found this blog post useful, please do share with anyone who might find it useful. If you enjoy my posts regularly, please consider contributing so I can keep this page up and running (no pun intended).