New study: Too much time on the bicycle can lead to infertility

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How much bicycling is too much if you're trying to start a family?

Lengthy and frequent bicycling — like more than 186 miles a week — can cause “significant fertility problems” for men, says a report presented to the European Society of Human Reproduction and Embryology.

But bicycling to work on a daily basis wouldn't cause a significant increase in abnormal sperm.

This isn't another urological study about saddle pressure causing male impotence. The current study from the University of Cordoba Medical School finds that tight clothing that holds heat, friction of the testes against the saddle and the stress from hours of high-energy exercise can contribute to inferior sperm quality.

Freezing sperm

A BBC report on the study says that most men have 15% to 20% “normal-looking” sperm. The Spanish study tested triathletes who trained in swimming, running and cycling to see if those activities affected sperm count.

The triathletes who trained 9 times a week for 8 years had less than 10% normal sperm. Those who bicycled 186 miles or more a week during training had only 4% normal sperm, which can hamper conception without fertility treatment.

The author of the study, Professor Diana Vaamonde, suggests that elite cyclists might consider freezing and storing their sperm before embarking on a career.


As you can imagine, more research needs to be done. One thing the researchers don't know is whether the sperm recovers after the men reduce or quit the high-mileage bicycling. In a Telegraph story on the subject, Vaamonde is quoted as saying the negative impacts could be permanent, although she doesn't know for sure.

Also, they want to study if there's a way to reduce the sperm damage. Vaamonde said:

“Depending on the mechanism leading to creation of abnormal sperm, these could include giving antioxidants and modifying training regimes to all for recovery.”

How to decrease sperm

I was amazed that only 15% to 20% of male sperm is viable. Looking around, I discovered there are many ways to reduce sperm without bicycling 186 miles per week. Here are a few I gleaned from the web:

Growing old;
Use of cocaine, marijuana, cigarettes;
Heavy drinking;
DDT, PCPs, dioxins, and a long list of other toxic chemicals.

Touring and recreational riding

What I'm wondering about is the effect from bicycle touring. Someone on a cross-country bicycle trip certainly logs more than 186 miles a week — probably double that. But in most cases it's only a three-or-four-month activity.

Also, is there a benefit from giving up recreational or weekend-warrior bicycling for those trying to start a family?

Let's hope the research decide to study these issues next.

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