How Does Exercise Affect Testicular Health and Function?
Exercise may be the best thing you can do for your health. Habitual exercise supports a healthy weight, prevents cardiovascular disease, treats type II diabetes, slows the progression of Alzheimer's, alleviates depression, and helps you sleep, among many other benefits.
But is exercise such a great thing for testicular health?
That's the focus of a new review paper published to the European Journal of Applied Physiology. University of Aveiro researchers Bárbara Matos, Rita Ferreira, and Margarida Fardilha teamed up with John Howl, a Professor of Molecular Pharmacology at the University of Wolverhampton, to parse through the mixed literature on testicular function and exercise.
To briefly summarize, physical activity is generally beneficial for male reproductive health, especially if it treats obesity, but certain types of exercise and overtraining can produce negative effects. Now let's dig in to specifics.
Moderate intensity aerobic exercise, including swimming, running, and playing recreational sports, is generally good for testicular function. The same is true of resistance training (weightlifting).
"Several population-based studies reported a positive association between moderate-intensity aerobic exercise training and testis function parameters such as sperm concentration and hormonal serum levels. Indeed, increased serum levels of total and free testosterone, sperm count, motility and morphology were observed in trained subjects," the authors wrote.
However, the authors also noted that a few studies showed no impact or slightly negative effects from moderate aerobic exercise and resistance training, resulting in lower levels of follicle-stimulating (FSH) and luteinizing hormones (LH). FSH stimulates spermatocytes to undergo cell division, while LH regulates testosterone levels.
Looking at the big picture, the majority of research does seem to indicate that resistance and aerobic exercise may slightly benefit testicular function. High-intensity interval training also seems to fall into this category.
The same can't be said for repeated high-intensity exercise, however. Physical training that involves exhaustive activity for sustained amounts of time does seem to be detrimental to testicular health. This is likely due to overtraining and fatigue. Marathoners, triathletes, and professional athletes are the most susceptible.
"One randomized controlled longitudinal study involved 362 habitual aerobic male athletes, aged 20–40 years, submitted to 60 weeks of a running program (five sessions/week, 120 min/session at speed adjusted to VO2max of 80%). In this study, lower serum levels of total and free testosterone, higher levels of SHBG, and decreased semen parameters like sperm count, motility and morphology were observed," the researchers summarized.
Long-term cycling seems to be detrimental to testicular health, as well.
"Testicular mechanical trauma, the result of compression against the bicycle saddle, and increased scrotal temperature may both induce an inflammatory response with negative outcomes in testis function," the authors wrote.
The net takeaway from the review is that the relationship between exercise and testicular function is nuanced. Exercise frequency, body type, amount of recovery, type of clothing (tight or loose), environmental temperature, and any exercise-induced injuries all factor in.
Moreover, any potential negative effects from overtraining or fatigue almost always resolve with appropriate recovery. While exercise can cause testicular or fertility issues, any associated harms rarely last.