Spending time on a bicycle seat, which has been linked to erectile dysfunction in men, may also be a hazard to a woman’s sexual health, a new study shows.

Many women who cycle or take spin classes are familiar with the numbness that sometimes can occur from sitting on a traditional bike seat. Bike seats are designed in such a way that body weight typically rests on the nose of the seat, which can compress nerves and blood vessels in the genital area. In men, this raises the risk of erectile dysfunction, something that has been documented in studies of male police officers on bicycle patrol.

But female cyclists have not been studied as closely. A study by Yale researchers in 2006 found that female cyclists had less genital sensation compared with a control group of female runners. As a result, some scientists believe that female cyclists probably are at similar risk for sexual problems as male riders.  In the latest study, the Yale researchers tried to determine whether there are specific factors that influence soreness and numbness among female riders. Forty-eight women took part in the study, each a consistent rider who cycled a minimum of 10 miles a week, but typically much more. The researchers mounted the women's bikes on a stationary machine in their lab and observed the women's biking positions.  It was the position of the handlebars that seemed to have the most effect. Women on bikes with handlebars positioned lower than their seats experienced more pressure in an area of soft tissue called the perineum, and had decreased sensation in the pelvic floor.

The researchers found that the lower the handlebars in relation to the saddle, the more a woman has to lean forward, forcing her to put a greater percentage of her body weight on the perineum. This problem is particularly likely to occur when a rider leans forward, flattens her back and puts her hands on the “drop bars” of a road or track bicycle for a more aerodynamic position.

“We’re basically showing that there may be modifiable risk factors associated with female riders,” said Dr. Marsha K. Guess, an author of the study and an assistant professor of obstetrics, gynecology and reproductive sciences at the Yale School of Medicine. “This better positions us to educate riders on safe riding practices that may actually be beneficial to reduction of pressure and lost sensation in the pelvic floor.”

The findings, published online in The Journal of Sexual Medicine, help shed further light on the problems faced by female riders but more study is needed.