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The Menstrual Cycle

The menstrual cycle is a vital biological rhythm. Despite it affecting 50% of the population, it is still a bit of a taboo subject and something people do not freely discuss. At primary school all I really remember about our very few lessons on the menstrual cycle was being horrified after watching how big a tampon swells after being dunked into a mug of water. The boys in our class weren’t even included in these lessons and were instead taken to another classroom to learn how to wash their penises properly…

Until the 70’s sport science research didn’t even include women in their research, which to me, is just baffling. Even now, most scientific studies exclude females due to the unpredictable shift in hormones.

Below are some of the areas related to sports performance that may become affected during a females cycle.

Brain function

- Mood

- Cognition

- Arousal levels


- Heart rate and rhythm

- Stroke volume

- Blood pressure

- Coagulation

- Vascular function

- Sympathetic activity


- Ventilation

- Asthma


- Core body temperature

- Thermoregulation

- Resting oxygen consumption

- Substrate availability and metabolism


Aerobic Capacity (VO2 max)

Anaerobic capacity

Response to ergogenic aids

- Glucose

- Caffeine


- Injury rate

- Ligament laxity

- Low back pain

As you can see from the list above, there are quite a few things that can be impacted over the course of the month. Of course, not everybody is the same. Keeping track of mood, performance markers and other variables during the time of the month can help work out what is best for you. These measurements can be a good indicator of whether you should hit it hard in the gym and maybe even push for a PB or have a bit of a de-load week, avoid anything too complex and generally go easier on yourself. I for one, have certainly thrown a few tantrums in the gym and been pretty frustrated with myself after a tough session and where I have felt really weak... only to find myself riding the crimson wave the next day. Knowing where you are in your cycle can just mean you cut yourself a bit of slack sometimes.

So lets break it down. What are the different stages and what do them mean for you in terms of training?

The average cycle lasts 28 days. A woman’s cycle, however can vary anywhere between 21 and 35 days so it’s a good idea to keep track of what is normal for you. There are plenty of app’s that can easily keep track of the time of the month with features to track mood, appetite, energy levels and other health markers such as: Flo, FitrWoman and Clue

The cycle consists of two main phases and two main hormones that fluctuate throughout: Oestrogen and Progesterone.

The Follicular phase

This starts on the first day of the menstrual bleed. Oestrogen is the dominant hormone during this phase which rises after the first few days into your menstruation (bleed). As a hormone it increases the body’s ability to utilise carbohydrates as a source of fuel which helps to decrease your appetite. If you are trying to make changes to your current diet, this may be a good time to get stuck in as adherence will be slightly easier to do during this phase as food and sugar cravings are lower than they are later on in the cycle.

There has been research to support higher strength gains and better performance during these first two weeks of menstruation. A 2016* study looked at the differences between women who trained during different phases of their cycle. Results showed participants who trained only in the the follicular stage showed greater power, strength and a increase of lean body mass compared to participants who trained during the luteal phase.

What does this mean for you?

  • The follicular phase is a good time for starting a diet

  • Good time to generally push yourself a bit harder in the gym and utilise the strength gains during this period

  • Just before ovulation (which occurs around day 14) there is a peak in testosterone which can be good time to push for a PB (personal best) in a lift

  • Repair of muscle tissue has also been found to be better during this stage so you are able to recover better from more intense workouts

The Luteal phase

As the body moves into the luteal phase and oestrogen reduces, progesterone becomes the dominant sex hormone. Strength levels can be reduced and co-ordination and balance also tend to be a bit trickier. Not all women see such a divide over the month but it is good to track so if you do feel things are a bit trickier, cut yourself some slack!

During this phase there is an increase in body temperature which leads to your body requiring more calories. An increase in hunger levels and cravings means trying to attempt to start a new diet here will be tricky as adherence will be a lot harder than in the first part of your cycle. It might even be better to aim for maintenance calories during this phase of your cycle.

  • You might want to take it a bit easier with training- take a bit longer with your recovery or work on less technically demanding lifts in the gym

  • With craving being hard to resist during this phase especially in the lead up to your next menstruation, it may be a better time to eat at maintenance calories

  • Emotions tend to be a bit higher with the increased rise of progesterone, you may also feel more lethargic and a bit less 'get up and go'

  • Pre menstrual syndrome; this occurs in the days leading up to your next menses (start of the next cycle) Here symptoms include low mood, bloating, fatigue, cramps, breast tenderness and the want to curl up into a ball. Not everyone has such severe symptoms but gentle exercise can help here, try a walk, yoga and anything that makes you feel good!

  • It is important to remember everyone is different and some people can transition between the cycle without feeling much of a change, so do what feels good for you!

Weight fluxions occur throughout the cycle due to water retention and bloating. If weighing yourself to track weight loss then make a note of where in the cycle you are. Try to compare it to the similar time of your cycle of the month previous for a better indication of weight loss/gain.

Take home messages:

  1. Try tracking a few months and log any changes in mood/ energy/ appetite: doing this will make you more in tune with you body

  2. Utilise the increased strength and energy in the follicular phase

  3. Ensure you are resting enough in the luteal phase

  4. If starting a diet- don't do it when its going to feel even harder. Use the first half where appetite is reduced and cravings are lower

  5. Listen to your body and find what works for you


Constantini, N., Dubnov, G. and Lebrun, C. (2005) The Menstrual Cycle and Sport Performance. Clinics in Sports Medicine, 24(2), pp. 51-82

Wikström-Frisén L, Boraxbekk CJ, Henriksson-Larsén K. (2016) Effects on power, strength and lean body mass of menstrual/oral contraceptive cycle based resistance training. J Sports Med Physical Fitness. (1-2), pp. 43-52

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