COPPELL, TEXAS—According to a Spanish study, men who cycle more than 186 miles a week have fertility problems with less than 4% of their sperm classified as normal.
Health Lambert and Danny Morgan are getting ready for an afternoon bike ride. Not your ordinary ride though. Both log more than two hundred miles a week. For Heath and Danny, the Spanish study raises some eyebrows.
"It's a bit of a concern and it causes me to do my own research." Danny says. "The important thing is being fit properly on the bike, making sure everything fits good."
Heath doesn't sound convinced.
"I know there are a lot of pro tour cyclist out there that have, and I know a lot of people in our group, that have ridden many many miles for many many years that have kids."
Baylor-Dallas urologist Matthew Shuford says the study focussed on two things, heat, and the pressure of the bicycle seat.
"Heat, for a long time has been know to adversely effect semen parameters." Dr. Shufor says. "So clearly that probably is related in someway, but the fact that they saw it worse in bicycle riders than runners may suggest that there is something else at work."
Where the cyclists bottom meets the seat is where the rubber meets the road. That's the source of the friction, mile after mile of it. Scientists blame the decline in sperm quality on the friction and heat fueled by tight clothing. Heath isn't too worried, he and his wife have no plans of having kids. Danny is single and isn't sure if kids are in his future. Scientists say cyclists may want to freeze sperm to protect their fertility, that is a road that Danny hopes he won't have to ride.
"I don't know, I'll have to see how much it costs."
Here is the good news, doctors say if long distance cyclists stop riding for a few months, their sperm will likely improve.