When you are trying to conceive, you may be wondering how exercise affects fertility. This is a simple question with a somewhat complex answer that depends upon many individual factors. So, the first piece of guidance is to reject any “one-size-fits-all” advice you may have heard because no one recommendation is suitable for everyone.
Another point to keep in mind is that exercise confers substantial benefits for parent and child, so if you can exercise to any degree, that is highly recommended.
To address the intricacies of exercise and fertility, this article presents findings from current research to help you make the most informed choices or support you in coaching clients during this time. It is important to note that individual guidance from a medical provider is essential, as these professionals have the most complete picture of each person’s health profile and needs.
Read on to learn:
- What infertility is and what causes it
- How exercise impacts fertility
- How to maximize fertility outcomes
- Guidance on exercise and IVF treatments
- Whether exercise can cause a miscarriage
Quick Answer: It appears that moderately active men and women have the best reproductive function and fertility outcomes. Extremes on either end of the activity spectrum appear to reduce fertility. Working out while trying to conceive is a smart option, as long as both partners are mindful of avoiding long bouts of vigorous exercise (>60 minutes of high-intensity or high-calorie-burning activity). Individual factors like body composition and fitness history also play a role, so guidance from a medical provider is always recommended.
What is Infertility and What Causes It?
Infertility is defined as the inability of a couple to conceive within one year of trying to become pregnant through unprotected sex.
According to the latest World Health Organization report from April 2023, infertility affects 1 in 6 couples globally, and this statistic persists among high and low-income populations (WHO, 2023).
Causes of Infertility are equally attributable to female and male factors. Female factors include tubal, uterine, and ovarian disorders (i.e. endometriosis, fibroids, PCOS) as well as endocrine system imbalances (some of which will be discussed in the next section). Male factors include low sperm production and quality as well as ejaculatory difficulties.
Because infertility is relatively common, efforts at understanding modifiable lifestyle factors have been of interest. Exercise falls within this category, so let’s look at how exercise impacts fertility.
How Does Exercise Impact Fertility?
Overall, staying active and fit is far more advantageous than being sedentary. However, it is important to keep in mind that physical activity exists on a spectrum, and it appears that its effects on fertility may be “positive up to a certain level and have a negative effect above that threshold level of activity” (Gudmundsdottir, et.al, 2009).
That said, these effects depend partly on a woman’s pre-pregnancy body mass index (BMI). If a woman is starting out overweight or obese, exercise can improve fertility outcomes. If a woman is underweight or “normal” weight and engages in more vigorous activity, then exercise can reduce fertility outcomes.
The mechanism behind the poorer outcomes has to do with the effects on the endocrine system. Exercise is a type of stressor, and when that stress exceeds a certain level — repetitive, longer sessions of vigorous exercise — it can lead to reduced energy balance (more calories out than in), which reduces female reproductive capabilities (Warren & Perlroth, 2001).
In the research, this has been especially true for athletes participating in sports that have an aesthetic component (i.e. gymnastics, dance), likely due to the pressures of keeping body fat and weight low.
This concept of high-calorie-burning activities being detrimental holds true for males, too. A “high volume of sustained physical activity, which has a significant caloric cost, can be accompanied by a transient suppression of reproductive function in both men and women (Redman, 2006).” Oxidative stress, derived from more vigorous exercise (as well as caloric deficit), negatively impacts sperm quantity. Endurance activities (i.e. cycling, running) seem to be the most well-correlated type of exercise that reduces sperm count and can increase the incidence of erectile dysfunction.
How Can You Maximize Fertility Outcomes?
It appears that moderately-active men and women have the best reproductive function and fertility outcomes. Extremes on either end of the activity spectrum appear to reduce fertility. Therefore, take a balanced approach. Working out while trying to conceive is a smart option, as long as both partners are mindful of avoiding long bouts of vigorous exercise (>60 minutes of high-intensity or high calorie-burning activity).
Keep in mind that these recommendations are only for the period in which you are trying to conceive. If your body is accustomed to higher-intensity exercise, you can return to that once you’ve gotten the all-clear from your medical provider (typically 1-2 months after successful fertility treatments). Just ease back in, so that your body has a period of adjustment, before ramping up the intensity.
Exercise and IVF Treatments
If you are undergoing in vitro fertilization (IVF) — or working with a client who is — there will likely be a period of exercise restriction following embryo transfer, as the body needs to support the implantation process. Exercise restrictions will vary depending on the individual, the protocol, and how the body is responding to treatment. Therefore, it is important to follow the guidance of your medical team. If you are coaching a client undergoing IVF, you need explicit medical clearance before continuing or resuming training. Once your client is cleared to resume, begin at a lower intensity until your client feels ready to progress.
The Bottom Line
If you are currently trying to conceive, the most important takeaway is this: keep moving. A balanced, moderately active lifestyle supports your overall health and your fertility. When pregnancy does happen, exercise continues to pay dividends (for you and your baby).
Can Exercise Cause a Miscarriage?
If you have struggled with infertility, it is natural to also worry about the risk of miscarriage. For information on the relationship between exercise and miscarriage, see this post on Can Exercise Cause Miscarriage?
Sources
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Gudmundsdottir, S. L., Flanders, W. D., & Augestad, L. B. (2009). Physical activity and fertility in women: the North-Trøndelag Health Study. Human Reproduction, 24(12), 3196-3204.
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Morris, S.N., Missmer, S.A., Cramer, D.W., Powers, R.D., McShane, P.M, & Hornstein, M.D. (2006). Effects of Lifetime Exercise on the Outcome of In Vitro Fertilization. Obstetrics & Gynecology, 108(4), 938-945.
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Redman, L.M. (2006). Physical activity and its effects on reproduction. Reprod Biomed Online, 12, 579-586.
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Warren, M. P., & Perlroth, N. E. (2001). Hormones and sport-the effects of intense exercise on the female reproductive system. Journal of endocrinology, 170(1), 3-12.
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World Health Organization, (2023, April 3). Infertility. https://www.who.int/news-room/fact-sheets/detail/infertility
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World Health Organization, (2023, April 4). 1 in 6 people globally affected by infertility: WHO. https://www.who.int/news/item/04-04-2023-1-in-6-people-globally-affected-by-infertility