We know that what we do and what we eat affects our overall health — and that means it also impacts the quality of our sperm and eggs. When we think of healthy living, we almost always think of exercise. Exercise is an important part of our lives that can help us maintain a healthy weight, healthy blood sugar levels, and decrease our stress.
Can exercise negatively affect sperm production?
The short answer is “Yes!” and the very long answer is “Yes, but it depends on the type of exercise.”
For men, the number one type of exercise that results in poorer sperm quality is bicycling. Before we can unpack how bicycling affects sperm, we have to understand why the testicles (the sperm-producing factory of the body) reside in the scrotum.
Testicles need to stay cooler to make sperm — so they are packaged in a sack of skin called the scrotum which hangs below the body. This allows them to maintain a temperature that’s roughly 3℃ (or 5℉) lower than the rest of the body, which is the optimal temperature to easily make sperm. When a man bicycles for long periods of time, this causes the testicles to sit closer to the body and increase the overall temperature. Every degree above normal leads to a 40% reduction in quality sperm. It is not only prolonged exposure to a higher temperature that can be causing a problem in sperm, but also the compression, or local trauma, to the testicles from the bicycle seat.
What if I don’t want to stop bicycling (but want healthy sperm)?
Desipite the research, that doesn’t mean men shouldn’t ride bikes at all! In 2011, a study at a Boston fertility clinic found moderate bike riding (fewer than 2 hours per week) didn’t have an effect on the number of sperm or the quality. Men who rode their bike more than 5 hours per week had a greater reduction in the number of sperm and the number of sperm that were moving.
A study in 2010 also examined the effects of running on sperm health. The men in the study were moderate runners so they didn’t notice any overt issues in their sperm. Whereas another 2009 study found that men who ran 108 km or more per week had suboptimal sperm and lower testosterone, but men who ran 54 km or less per week didn’t have the same issues.
What should I do if I’m trying to conceive?
If you’re trying to conceive, male partners may benefit from avoiding biking for more than 5 hours per week or running more than 108 km a week. There is some evidence that shows these activities done at longer intervals may impact the quality of the sperm and lower testosterone.
- Jones, R.E., & Lopes, K.H. (Eds.). (2014). Human Reproductive Biology. Academic Press.
- Appell, R. A., Evans, P. R., & Blandy, J. P. (1977). The effect of temperature on the motility and viability of sperm. British journal of urology, 49(7), 751–756. https://doi.org/10.1111/j.1464-410x.1977.tb04566.x
- Wise, L. A., Cramer, D. W., Hornstein, M. D., Ashby, R. K., & Missmer, S. A. (2011). Physical activity and semen quality among men attending an infertility clinic. Fertility and sterility, 95(3), 1025–1030. https://doi.org/10.1016/j.fertnstert.2010.11.006
- Vaamonde, D., Da Silva-Grigoletto, M. E., García-Manso, J. M., Vaamonde-Lemos, R., Swanson, R. J., & Oehninger, S. C. (2009). Response of semen parameters to three training modalities. Fertility and sterility, 92(6), 1941–1946. https://doi.org/10.1016/j.fertnstert.2008.09.010