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 a host of wonderful benefits for parent and child, so if you can exercise to any degree, that is highly recommended.
To address the intricacies on the topic of exercise and fertility, this article provides findings from current research so that you can make the most informed choices for you and your family. In addition, it is important to listen to the guidance offered by your medical provider, who will have the most complete picture of your health profile and needs.
NOTE: This article uses specific gendered language because that is the convention used in the research.
What is Infertility and its Causes?
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).
But, 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.
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?
Want Additional Resources?
For additional resources to help you exercise safely and effectively during pregnancy, explore our training programs and services. You’ll find a variety of offerings tailored to different needs — from education, to self-guided programs, to the ability to work with an expert coach.
Or, if you’re a health & fitness pro interested in coaching pre & postnatal clients, check out our ProNatal Education & Certification.
Sources
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.
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.
Redman, L.M. (2006). Physical activity and its effects on reproduction. Reprod Biomed Online, 12, 579-586.
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.
World Health Organization, (2023, April 3). Infertility. https://www.who.int/news-room/fact-sheets/detail/infertility
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