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Freediving and the Menstrual Cycle

By: Paula Johnsson

Besides muscle mass and body size, one crucial thing sets male and female athletes apart: the menstrual cycle. Menstruation in sports is a double-edged sword. On one hand, it’s a sign that you are healthy and that you can progress optimally (since the absence of a period can have significant health consequences). On the other hand, the menstrual cycle is another stressor that can potentially affect women negatively on the days they need to perform. Not all sports are affected the same way by the monthly cycle. However, freediving pushes your body to extremes, and subtle changes in your physiology will become more noticeable than in many other sports. 

Menstrual cycle

To put it simply, you can divide a (natural) menstrual cycle into two phases: the follicular phase with low levels of estrogen and progesterone, and the luteal phase with high levels of estrogen and progesterone, see picture below. 

The drop of progesterone and estrogen triggers bleeding and defines day 1 of the menstrual cycle. Gradually, estrogen increases, and together with FSH and LH (not in the picture) they trigger the release of an egg from the follicle – ovulation. The remains of the follicle turns into corpus luteum, which then secretes high levels of progesterone and moderate levels of estrogen. Progesterone peaks circa one week after ovulation. Roughly one week or a few days before the period begins, many women experience PMS symptoms, such as mood disorders, bloating and constipation. 

Progesterone and estrogen chart

Freediving and the Menstrual Cycle

In freediving and breath-holding, it can become very noticeable when your physiology changes, and it can lead to dives feeling easier or more difficult. This is especially true during certain phases of the menstrual cycle. 

During menstruation, you are in the early follicular phase and generally your hormones play in your favor. However, a lot of people still have issues with cramping and fatigue during the first days of bleeding, and diving during this time can be challenging for some. 

During the later part of the follicular phase, when the heaviest days of bleeding are finished and up until ovulation, most people feel they are at their strongest and ready for a challenging training session or even a max dive. Some people feel their best at ovulation, but some feel worse around this time due hormone changes or pain around the ovary that is releasing an egg.

After ovulation until menstruation (also known as the luteal phase) progesterone is produced. Progesterone contributes to an increase in respiratory rate, basal body temperature and heart rate, along with a decrease in HRV (heart rate variability) and CO2 tolerance. In freediving, where we want a low pulse and calm breathing, dives can suddenly feel more challenging. This usually becomes more noticeable during the later part of the luteal phase. 

If some of these factors affect you a lot, such as a decreased CO2 tolerance or cramping, you might not want an important competition to take place during this time. 

Lack of Scientific Knowledge – Freediving during a Menstruations Cycle

The Swedish Sports Federation provides physiological support to elite athletes in all sports. I asked them if they had any recommendations on how female athletes, who feel their performance is affected by the menstrual cycle, should approach their menstrual cycle and important competitions. They had no answer but referred to studies on how to train based on the menstrual cycle. The recommendations were for resistance training, and suggested that doing a little more volume during the follicular phase could lead to greater hypertrophy (muscle growth) than if you were doing equal amounts in the follicular and luteal phase, presupposed that the total volume over the months trained was the same. I was happy that they had some material to recommend, but still disappointed that they couldn’t provide any guidelines regarding how to handle the menstrual cycle before important competitions. 

Although there are a few studies now on how to train according to the menstrual cycle, I must stress that knowledge about this topic is still in its infancy. We simply don’t have enough quality studies yet. But even if we don’t have scientific evidence on how to train and when we perform the best, I think it is of great value to share personal experiences and theories. Bacteria affected humans long before there were any scientific studies there to prove it. Just because we don’t see something doesn’t mean it’s not there.


I conducted a questionnaire to female freedivers in 2023 which was filled out by over 200 respondents. One thing that I discovered was that the “worst day of the cycle” varied much more than I expected. Some feel their worst during the days of heavy bleeding and cramping, while others want to avoid the days of PMS, and others feel bad during ovulation. Regardless, most considered the menstrual cycle to be a major stressor leading up to a competition. This is something I really hope freediving coaches of all sexes consider. Not only do athletes with a menstrual cycle have to consider tapering, diet and mental preparations before a competition, but they also have to deal with competitions on their “bad” cycle days. 

When going through the questionnaire it became clear to me that the effects of the menstrual cycle are highly individual, so even if we do know a little bit about how the cycle affects women on a broader scale, it’s difficult to give generic advice. Hormone levels in your 20s are not necessarily the same as they are in your 40s when you are entering the perimenopausal years, i.e. the years before menopause. And there are also differences in hormone levels between someone with a natural cycle and someone who uses hormonal birth control. The mechanisms for hormonal birth control also differs, as some only have synthetic progesterone while others have synthetic variations of both estrogen and progesterone. There is also variability from cycle to cycle for the same woman, which can depend on a variety of other factors, e.g. diet, stress, alcohol etc. In real life, a woman’s cycle is not text book 28 days long with same hormone variations every month. 

I can’t say how you should cope with your menstrual cycle and your freediving training and performance, because it’s so individual. However I have had great benefits from learning more about and tracking my cycle. Combine this with keeping a log of your training and you will be able to notice patterns of when training feels easier and when it feels more difficult. If you want to learn more about some of the ways hormones can affect your physiology and freediving, you can watch this video:

Final thoughts

Start talking about this topic! Let’s get rid of the old taboo around menstrual cycles by talking about them. Share your experience, and ask questions. Personally, I have found that a lot of men are also interested in this subject.

The freediving community needs scientific studies on freediving and the menstrual cycle. The few studies that have been done are rather small, and sometimes they just mix natural cycling women with those who use hormonal contraception. Ideally, we would create science backed recommendations on how to train and preparing for competitions. 

Finally I want say that even if this article focused on how the menstrual cycle can affect freediving, body literacy and understanding your cycle can be of great benefit in so many other aspects of life. It can help you become as strong as you can be, (avoiding) getting pregnant, and tell you a lot about your health. You can make more informed decisions and build confidence in yourself. Knowledge is power!

Author Bio PicturePaula is a Swedish pool freediver with several national records and Swedish champion titles. For several years, she has been passionate about sharing information on the topic of how the menstrual cycle can affect freediving. You can keep up with Paula via her Website, Instagram, or YouTube Channel!

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