Your menstrual cycle as a runner: Impacts on performance and injury risk

Dr Breanne Kunstler (BBiomedSci, BHealthSci, MPhysio, PhD).

Physiotherapist, behaviour change scientist and run coach.

This is written for the female recreational athlete not taking hormonal contraception and not currently pregnant or breastfeeding.

Why do I track my menstrual cycle?

As a 30-something year old woman, I have paid close attention to my menstrual cycle for several years. I mainly did this because I wanted to start a family, but now it’s because I know that I feel better and worse when I run depending on the time of the month. It turns out there’s a scientific explanation for this!

Menstrual cycle 101

You need to know a couple of things before I begin this post.

1. Week 1 of the 4-week menstrual cycle (typically it’s 4, but it can vary) is when you have your period (“monthly bleed”) and hormone (oestrogen and progesterone) levels are low.
2. Oestrogen levels peak before ovulation, or release of an egg, which happens about 2 weeks after the beginning of your monthly bleed or half way through the cycle.
3. At ovulation, oestrogen levels decrease as progesterone levels increase. This is the beginning of the second 2-week phase and happens right before your period. You can feel like shit during this time (acne, bloating, moodiness…chocolate…).
4. If fertilisation doesn’t occur, the monthly bleed will commence and the cycle starts over again.

Source: Clue

Running can feel different depending on the time of the month

I woke up this morning, and yesterday morning, feeling tired and run down. This is despite getting more sleep than usual. I decided to go for a run to make myself feel better. It certainly made me feel better, but the run felt slow and heavy. It just wasn’t as easy as usual to run and the whole session felt, well…meh. 

According to science, it is normal to have poorer running economy (or efficiency) during the second half of your cycle, or after ovulation and before your period. Women have reported feeling unable to run as fast and hard as usual during this time. This makes me wonder if I'm putting myself at risk of injury if I’m running with poorer efficiency and it just feels shit?

You might have a greater injury risk at ovulation

Oestrogen has protective effects on muscle and bone. It does wonderful things for the development of strength and fitness of the recreational runner as it promotes bone and muscle growth and repair after exercise. So, having a regular menstrual cycle where oestrogen levels are able to increase and decrease normally is extremely valuable.

However, high levels of oestrogen (such as right before ovulation) can put us at risk of ligament and and tendon injuries because it makes them weaker. So, sure, oestrogen can be our friend when making our muscles and bones stronger, but peaks in oestrogen can put us at risk of damaging ligaments in our joints like our knees and ankles.

How can you track your menstrual cycle?

There are many smartphone apps you can use to track your cycle (e.g. Clue). I used Clue when I was trying to conceive. I have tried using the menstrual cycle tracking function in my Garmin app because this app is a one-stop-shop for all of my running related information (and I have a Garmin watch). But the fact that the menstrual tracker doesn't even ask me if I have my period or not reduces my confidence in the usefulness of the app. Using the one app for tracking my menstrual cycle and my training outcomes will make it easier for me to correlate data related to my cycle and my running. Fitrwoman does this so I'm going to give that a go now.

How will I use this knowledge to inform my training plan?

Feeling ordinary and potentially having an increased injury risk doesn’t mean that we should take more control over the menstrual cycle (e.g. by encouraging athletes to take hormonal contraception, thereby minimising normal hormonal fluctuations). Instead, we need to respect that women might need to modify their training schedules depending on the time of the month.

I plan to change my current running program in three ways:

1. I'll enter data related to my menstrual cycle into my Garmin app daily and use the data to know when I should and should not do certain activities; 
2. I’ll avoid strenuous sessions, especially those that use uneven surfaces or have heaps of plyometric exercises (e.g. single leg hops), half way through my cycle when oestrogen is highest because these sessions stress potentially weakened ligaments and tendons; and
3. I won’t schedule any races in the second half of my cycle. Instead, I’ll schedule them for the beginning of my cycle when I’ll be able to run faster and enjoy them more. This is easy to do with virtual races that allow you to run at any time over several weeks. I might need to skip less flexible events.

Keep this knowledge in your back pocket for the next time you wonder why you aren't enjoying your running as much as you usually would!

Want to know more about the menstrual cycle and running? Check out these extra resources.

Dr Nicky Keay talks about the influence hormonal changes can have on athletic performance in this podcast. 

Check out Dr Keay’s website here, where she has an awesome evidence-based blog on everything you need to know about hormones and performance.

Dr Stacy Sims talks about training and the menstrual cycle in this podcast. 

This website outlines the hormonal issues that can occur when athletes don’t look after their body with good rest and recovery (referred to as Relative Energy Deficiency in Sport). Check out my other blog posts on intuitive eating and exercise if you want to learn more about effectively fuelling your body for exercise and ditching 'diet culture' (part 1 and part 2)