Bike Riding May Lead to Scarring, Impotence

Q:  This may seem like a silly question, but I am a 48-year-old male in good shape, and I would like to add bike riding to my exercise program. The problem I am having is that a good friend told me that bike riding in an adult male may cause you to become impotent. Have you heard of any such study?

A:  When I first read your question it took me by surprise, too, and I was skeptical, but I found two very good studies from Europe published in 2001 that show a connection between erectile dysfunction and cycling.

They measured the oxygen pressure (pO2) in the penises of healthy athletic men before, during and after cycling because oxygen pressure correlates with blood flow. While standing, the average pO2 was 60.5 mm Hg (plus or minus 8.1), but declined dramatically to 18.3 mm Hg (plus or minus 5) while cycling in a seated upright position. After standing, the values returned to normal in 10 minutes.

The good news is that cycling in a reclining position resulted in pO2 levels of 59.4 mm Hg (plus or minus 4.2), similar to those obtained while standing. It's thought that sitting upright compresses the blood supply to the penis, especially with certain saddle designs. Over time, the lack of oxygen leads to scarring in the penile tissue, which may result in impotence.

To avoid this, a reclining bike is the best option; otherwise you should alternate between sitting and standing and take frequent breaks during long trips.

"Dear Doctor" is a compilation of patient questions answered by doctors from the Medical College of Wisconsin.