Diet and exercise are crucial for fertility, but could the type of exercise you’re doing actually be negatively impacting your ability to get and stay pregnant?
Physical activity is widely recognized as beneficial for overall health and wellbeing, but for women trying to conceive, the relationship between exercise and fertility can be complex. High-intensity exercise, in particular, has been shown to negatively impact fertility by altering key hormones. Understanding the impact of these hormones and how high-intensity exercise affects them is crucial for women looking to maximise their chances of pregnancy. I’ll also tell you which exercises are best for fertility. So let’s get into it!
FSH and LH disruption
One way that high-intensity exercise can impact fertility is by altering two hormones which play critical roles in the menstrual cycle and ovulation. FSH – follicle stimulating hormone – stimulates the growth of follicles in the ovaries in the first half of our cycle and LH – luteinizing hormone – triggers ovulation – this is the hormone that’s measured on the ovulation test strips. FSH also affects the levels of estrogen in our body, a hormone needed for ovulation and optimal growth of the endometrial lining. High levels of physical stress caused by high-intensity exercise have been shown to suppress the levels of FSH and LH, which can disrupt the normal menstrual cycle and affect ovulation. This can impact the ability of the ovaries to produce viable eggs, making it more difficult for pregnancy to occur. And remember, when we don’t ovulate, we also don’t produce progesterone, which further disrupts our hormonal balance and our ability to get pregnant. Additionally, a disruption in the menstrual cycle can also affect implantation, as the uterine lining may not be adequately prepared for a fertilised egg to implant.
Impact on thyroid hormones
High-intensity exercise can have a significant impact on thyroid hormone levels too. The thyroid gland is responsible for producing hormones that regulate metabolism, energy levels, and body temperature. During high-intensity exercise, the body undergoes physical stress, which can cause an increase in cortisol levels. Cortisol has been shown to suppress thyroid function, leading to decreased levels of thyroid hormones. In some cases, this can lead to symptoms of hypothyroidism, such as fatigue, weight gain, and cold intolerance. Additionally, excessive or prolonged exercise can cause inflammation, which may exacerbate an autoimmune condition.. If you are experiencing low thyroid symptoms, or are struggling to get or stray pregnant, you may want to have a full thyroid panel done to check the health of your thyroid. I would also advise to monitor your symptoms during and after high-intensity exercise . I had a client, for example, who would feel really cold for hours after a HIIT session. And I myself experienced a hoarseness in my throat for hours after doing a Crossfit session, which helped me come to the realisation that this form of exercise was too much for my thyroid to handle at the time.
Increased cortisol production
Cortisol is another hormone that plays a crucial role in fertility. Cortisol is known as the “stress hormone” and is produced in response to physical and mental stress. When cortisol levels are elevated, it can cause a decrease in progesterone, which is essential for a healthy menstrual cycle and pregnancy. A study by the American Society for Reproductive Medicine found that women who engage in high-intensity exercise have higher levels of cortisol, which can lead to a deficiency in progesterone and affect fertility. Additionally, excessive exercise can disrupt the menstrual cycle and lead to a condition known as hypothalamic amenorrhea, in which the ovaries stop producing eggs. Exercise in itself is a stressor – and that’s not always a bad thing – if done correctly, it can promote health and wellbeing through the release of endorphins, chemicals which are released during exercise which can make us feel good.
After all, it feels so good to go for a 5-10k run right? I hear you, I used to be a keen runner too in my day. Endorphins have been shown to reduce stress and anxiety, which can in turn improve the hormonal balance in the body. The problem is that endorphins can have a negative impact on female hormones, particularly if exercise is performed in excess. I know, right?! Excessive secretion of endorphins can interfere with the normal production of FSH and LH, which, as we saw, can affect ovulation and subsequent progesterone production, which consequently would affect implantation or the ability to stay pregnant. In males, excessive exercise has been associated with low sperm count.
So what to do??
Ok so before you cancel your gym membership and plop yourself on the sofa for the next few months, let’s clarify what I mean by high intensity exercise, and let’s have a look at the type of exercise which is not recommended when looking to conceive, and what is. The two forms of exercise which I would most discourage are running and spinning. I cannot tell you how many clients I have who use these two forms of exercise as a means to relax after a very stressful day, not realising that they are adding to that stress bucket. The way that I explain it to the students in the college is to think about it this way: if you are running for 5-10k on a regular basis, your body is going to start to think: hang on, what are we running away from here? There must be a danger we need to get away from, so it’s probably not a safe time to have a baby! Same goes for spinning – if you’re cycling like the wind for 45 minutes multiple times a week, your body is not going to feel safe to reproduce. I actually have 2 fertility clients whose diets were already quite good but were struggling to conceive. Both of them were keen runners. When asked to stop running as their main form of exercise, both of them conceived within the next menstrual cycle. True story!
Low body fat and fertility
If you are an athlete or train hard in any sport, including gymnastics or ballet, that may also be impacting your ability to get pregnant, especially if body fat is low. Fat cells play a critical role in hormone production, including the hormones necessary for ovulation such as estrogen. Women with low body fat may have difficulty producing adequate levels of this hormone, leading to a disruption in the menstrual cycle and making it more difficult to ovulate and conceive.
I would also not recommend the following types of exercises when looking to conceive: hot yoga, bootcamp or Crossfit style exercises. If you are exercising for more than an hour at a time and your heart rate is up during this time, that could also be a stressor. Or if you are exercising 6-7 days a week with no rest days, that could also be too much for your body. If you find yourself hyperventilating, or in a pool of sweat on the floor trying to catch your breath after a workout session, chances are you have pushed yourself too hard. A good rule of thumb is to see if you are able to breath through your nose whilst exercising.
When it comes to exercise and fertility, moderation is key. Aim to engage in moderate-intensity exercise, such as yoga, Pilates, or resistance training, for 30 minutes to an hour, three to four times a week. Swimming, dancing, going for a long walk in nature and even a leisurely bicycle ride in nature are great forms of exercise. Engaging in regular physical activity can help regulate the menstrual cycle, improve insulin sensitivity, and reduce stress levels, all of which can positively impact fertility. And don’t forget to ensure you are well nourished when you are exercising regularly, so that you have plenty of nutrients to fuel your body throughout your workout and the rest of your day.
If you are on a fertility journey and would like some extra support, I would love to chat to you! Click here to book a free discovery call and let’s chat about how some bespoke diet and lifestyle changes can help your fertility flourish.
Further reading:
Exercise intensity and its effects on thyroid hormones: https://pubmed.ncbi.nlm.nih.gov/16380698/
Interactions of Cortisol and Prolactin with Other Selected Menstrual Cycle Hormones Affecting the Chances of Conception in Infertile Womenhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC7588978/
