Flowerboy goes Menstrual - How the menstrual cycle influences different aspects of endurance performance.

Hey Maddy - tell us about what you studied and why you chose this topic -

During my PhD I was part of a research group called FENDURA- the Female Endurance Athlete project. I studied how the menstrual cycle influences different aspects of endurance performance- specifically different physiological aspects of performance, like VO2max, lactate threshold and heart rate, as well as certain aspects of recovery, like sleep, fatigue and muscle soreness. My PhD aimed at understanding if/how different aspects of performance and recovery fluctuate during certain timepoints of the menstrual cycle. For instance- is our body more/less “primed” for specific types of exercise during the bleeding phase compared to the ovulatory phase? Do we recover faster (or slower) earlier in the cycle vs. later in the cycle? Are we more or less fit during certain times of the cycle?

Someone asked about the number of participants in your study.

Each study included 20-30 participants. 

Was there anything that came up while studying that you didn’t expect?

I went into this project expecting big effects- that menstrual cycle could prove to be this secret key to unlocking female performance. We know from a number of subjective studies that 50-80% of exercising women report feeling their menstrual cycle influences their fitness and performance- so we wanted to understand what physiological aspects are driving these perceptions and moreover- is there a way women could be organizing their training to harness these effects (which is of course a very hot topic in the blogs- but there is actually very little research on these topics). But for the most part we found that the menstrual cycle has no little to no “group-level” effects on the body’s capacity for endurance performance. This means, that if we look at a group of women, do all/most tend to have higher lactate, higher heart rates, better sleep, etc. during one specific timepoint of the cycle compared to another - and the answer is no. There isn’t one phase of the menstrual cycle where we think that women would more/less “primed” for endurance exercise. In other words, there isn’t one specific phase were we would expect someone to be more/less likely to win a race. There isn’t one specific phase where women should avoid high intensity exercise because it’s too hard for our bodies and there isn’t one secret recipe for how women should be organizing their training in accordance with their menstrual cycle. Rather, the way women experience the menstrual cycle is very individual. Women experience different symptoms, with different severities, at different timepoint of the cycle- which may influence how their motivation to train or how they feel then they are exercising- but it doesn’t seem to affect everyone in the SAME way. We see some women who feel more fatigued or easliy exhausted during their bleeding days, while others actually feel their strongest during these days. Some womenhave difficulties sleeping before or during their bleeding days, and others who don’t have problems sleeping at all. It’s very difficult to describe this type of individual variability inresearch setting because in research we generally try to understand how the group responds, so we can understand what is “normal” for most people. But with the menstrual cycle there does not appear to be much consistently observable group effects- but rather that everyone is experiencing the cycle in their own unique way.

Is listening to your body the best wisdom or following the data/ research?

When it comes to aspects related to training around the menstrual cycle it is best to follow the wisdom your own body. Contrary to what you see in the blogs – we currently have no research to support the notion that any “one-size-fits-all” menstrual cycle phase-based training program would be particularly beneficial for all women. The menstrual cycle is highly individual, so the best thing you can do is get to know your own menstrual cycle and consider if it does (or doesn’t) affect your training- from there you can adapt your training plans based on your needs.

Currently our best recommendations are to track you own cycle, symptoms and experiences for 3-4 months and start to look for patterns specific to your body. For instance, are there certain times during your cycle when you feel more or less motivated to train, when you feel stronger or weaker, when certain sessions feel more or less exhausting? Do you have reoccurring symptoms that influence your training plans (i.e.stomach cramps, muscle pain, difficulties sleeping)? Once you understand your own cycle you can consider if adapting your training to these patterns would be beneficial to you.

Peak week training during literal menstrual phase - any tips / things to look out for?

I am not familiar with this concept. We don’t have any scientific evidence to suggest that organizing your “peak week training” during the luteal phase would be any more beneficial than doing it in a different menstrual cycle phase- but if it works for that is great!

So there is all these physical attributes to athletic pursuits,but you mentioned there hasn’t been many studies on determination? Tell us about that.

While there's a ton of research on physical traits like VO₂ max, lactate threshold, and muscle fiber types, psychological factors like determination, grit, and mental toughness are less studied — even though they clearly play a huge role in athletic success.

In endurance sports, mental toughness and determination are often key factors that separate the good athletes from the great athletes. To be a great athlete you need to push through a lot of discomfort, confront pain over and over again, stay consistent, and show up even when you’re tired or unmotivated. These traits can’t be tracked on a heart rate monitor — but they often make the biggest difference when it counts. While we can measure physical metrics in a lab, it’s much harder to measure traits like determination in a consistent, scientific way. That's one reason it's been studied less. Plus, mindset is deeply individual — shaped by personality, life experience, and even culture- so what motivates one athlete might not work for another.

With that said, the science is catching up. Recent studies are starting to look more closely at how self-belief, motivation, goal-setting, and emotional resilience influences performance.We’re learning that much like physical training, mental skills can be trained using tools like visualization, self-talk, breathing exercises and mindfulness training.

What do you think is the most overlooked aspect of recovery?

Integrating proper and adequate recovery into your training program is just as important as the training itself. Without recovery your body can’t adapt, rebuild or perform at its best. In my opinion one of the most overlooked aspects of recovery is sleep. While we often hear a lot about stretching, foam rolling, cold plunging (all of which can be helpful) sleep is where the real magic happens. When you sleep your body releases hormones to help repair muscles, your brain processes motor learning skills and destresses and your muscles restore metabolically. These aspects are critical to optimizing performance-enhancing adaptations to your training and reducing the risk of over training or injury. Most adults do not meet the current sleep recommendations (7-9 hours per night)- so ensuring you get enough sleep is a very simple and efficient way to improve your recovery.

How to improve sleep quality:

In addition to sleep, nutrition and hydration are also highly relevant for proper recovery. These three areas (sleep, nutrition and hydration) form the foundation of athletic recovery – and have the greatest impact on athletic performance. Once you’ve dialed in this foundation you can build on it by incorporating other strategies like massage, cold plunging and other fads which have been the focus of less research.

Any words of wisdom as we finish this up?

We often try to fit all these training princples into neat little boxes - sets, zones, metrics, rules. But the truth is, progress isn’t always linear, and the human body and mind thrive on variety, flexibility, and balance. Some days you need to push, some days you need to pull back. Structure is needed to build strength and endurance, but creativity and trying new things is often what keeps us going. True growth comes from honoring the full spectrum - hard work, recovery, discipline, play, mindset, and intuition. And at the heart of it all is learning to know and understand your own body - how it feels, how it responds, when it needs rest, and when it’s ready to rise. The more in tune you are with yourself, the more effective and sustainable your progress will be.

So fuel well. Train smart. Rest deeply. And most of all, remember that no one element works alone — it’s the blend, and the self-awareness behind it, that makes you resilient, adaptable, and unstoppable.

This was an article written up about one of our studies- you might find other relevant info there: https://en.uit.no/nyheter/artikkel?p_document_id=856417

Thanks for taking the time, please comment any further questions you might have and we can ask Maddy to answer them in a follow up interview. 

Hope to catch you for a coffee and run soon !