How can cycling reduce fertility?
There are a few mechanisms whereby exercise could negatively impact upon fertility. Firstly, endurance athletes such as long-distance male runners (at least 108 kilometers a week) have been shown to have lower levels of testosterone, which could potentially affect reproductive function. This may also impact long-distance cyclists. In addition, the elevated scrotal temperature associated with cycling may adversely affect spermatogenesis (the process of making sperm cells). Previous reports have shown competitive cyclists can have abnormal sperm morphology (an indicator of healthy size and shape) and reduced sperm motility (the ability of the sperm to move and swim) during periods of racing.
New research
A study published in the journal Fertility and Sterility examined the link between regular exercise and semen quality among 2,261 men attending an infertility clinic over a 10 year period. The researchers found no negative effects for regular exercisers, however, men who reported bicycling as their primary form of exercise had a lower sperm concentration and lower levels of total motile sperm. They also discovered that the longer a man cycled, the greater the negative impact on total motile sperm, with men who cycled for 5 or more hours a week showing the lowest scores. They also cited previous research which found some cyclists experience genitourinary problems, such as erectile dysfunction and nerve entrapment syndrome (pain in the pudendal nerve in the pelvis, resulting in genital numbness, and urinary incontinence).
Lifestyle implications for cyclists
Men who are concerned about their fertility don’t have to stop cycling, especially if it’s at a recreational level. But if you are a serious rider, there are a few program adjustments you can make to reduce the stress on your testes and potentially reduce any negative impact on your fertility.
References available upon request