Oral contraceptives—The other side of the menstrual cycle coin
Recently, sport science has, thankfully, turned its attention to the role of menstruation in athletic performance (you should read LET’S TALK ABOUT MENSTRUATION. PERIOD.) It is not always obvious in research that approximately half of the adult population are women. In sports, around half of all women take some type of hormonal contraceptive. Most commonly, they use oral contraceptives.
Oral contraceptive is the medical term for what most of us know as the “pill”: a drug that you swallow to prevent pregnancy.
So, while we want to continue researching the menstrual cycle, we want to cater for the other half of sportswomen, too. We decided to flip the coin and took a long hard look at previous research on this topic. We investigated all studies comparing the performance of female athletes in their natural cycle with that of athletes taking oral contraceptives. We also looked at the pill-taking versus the pill-free days, to see if this influenced performance.
What is the pill, and how does it work?
There are many types of oral contraceptives—too many to mention here. Hence, we will focus on the most common type: the combined, monophasic oral contraceptive pill. This type of oral contraceptives was designed to mimic the natural 28-day menstrual cycle by having 21 pill-taking days and 7 pill-free days.
The primary purpose of oral contraceptives is to prevent pregnancy. They do this by changing the hormone levels that regulate your reproductive system. One of these changes is the blunting of the fluctuations in the levels of your reproductive hormones oestrogen and progesterone. Normally, these show an up-and-down pattern during your cycle. However, if you take an oral contraceptive pill, you have a low level of these hormones all the time.
But, your oral contraceptive pill acts as a double agent! It lowers your natural levels of oestrogen and progesterone. But it is also adding a synthetic oestrogen and progestin into your body. The pill you put in your mouth contains a chemically manufactured form of these hormones that imitates the natural form. That means you have two hormonal profiles at the same time: your natural one and the synthetic one imposed on it.
Take a look at this picture below. At the top, you can see the curve with the natural levels of your oestrogen (lilac) and progesterone (green) over the course of your cycle. Below, you can see how the daily doses of the synthetic oestrogen flatten the curves (no pun intended) of your natural hormones.
Why do we care about what the pill does to our bodies?
Firstly, we are trying to prevent an unplanned pregnancy. So, we care about this. Secondly, some women need to take oral contraceptives to help with other medical issues. This could be acne or period pain. So, we care about getting this help, too. Thirdly, we definitely care about the changes in our hormone profile. In fact, they concern us, as it is reasonable to believe that these changes can affect our health and our sports performance.
Our analysis of the previous research on this topic helped us to better understand if oral contraceptives affect athletic performance.
Do oral contraceptives influence your performance?
We showed that when compared with a natural menstrual cycle, oral contraceptives might result in a very slight reduction in performance in some women. BUT this effect was not present in all women. This means that some, but not all, women who take an oral contraceptive pill may have slightly poorer performance than those who don’t take the pill.
In fact, this finding was so small and so variable that we concluded that it does not warrant special guidance for athletes using oral contraceptives. So, basically, if you are using the pill as an athlete, you don’t need to worry. You are not at a disadvantage compared to an athlete who doesn’t take an oral contraceptive.
We also showed that exercise performance did not change between the 21 pill-taking and 7 pill-free days. This means that you don’t need to worry about which phase of your pill cycle (pill-taking or pill-free days) you are in when you compete or train.
However, you may want to find out how your cycle influences you personally, rather than be led by the research in other women. After all, every woman is different. Our advice is that you should track your own feelings, symptoms, and performance at different points in time during your pill cycle.
As mentioned, most sportswomen will not notice a difference. However, if you are affected by your hormones, this will enable you to make a change or plan based on your own personal observation.
You can empower yourself by:
- Talking to your support team and doctor about your choice of oral contraceptive. Make sure you are taking the one that suits you best.
- Tracking and monitoring your feelings, symptoms, and performance across your pill cycle. See if you notice a change between the pill-taking and pill-free days and what that is.
- This might be even more impactful if you record your feelings, symptoms, and performance when you are taking the pill. Then, you compare them with when you are not taking the pill. This will give you the best personalised information.
It takes a while for our bodies to respond. Hence, you will need to track your responses for at least three months when taking the pill. Then, you track them for at least three months when not taking the pill. Importantly, if you need protection from pregnancy, please use other non-hormonal forms of contraception during the pill-free times.
MORE TO TALK ABOUT FOR FEMALE ATHLETES
So, here is another thing we have to think and talk about: female athletes who take the pill and what it does to their mind and body. Observe yourself, then join the discussion and share your experience. You are at the centre of this critical new research field.
Martin D, Cooper S, Sale C, and Elliott-Sale KJ (2018). The prevalence of hormonal contraceptives in elite female athletes. International Journal of Sports Physiology and Performance, 13 (7), 926-932.
Elliott-Sale KJ, McNulty KL, Ansdell P, Goodall G, Hicks KM, Thomas K, Swinton PA, and Dolan E (2020). The Effects of Oral Contraceptives on Exercise Performance in Females: A Systematic Review and Meta-Analysis. Sports Medicine, [published online ahead of print]
Elliott-Sale KJ, Ross E, Burden R, and Hicks KM (2020). The BASES Expert Statement on Conducting and Implementing Female Athlete-Based Research. The Sport and Exercise Scientist, 65, 6-7.