For men, the health benefits of bicycling may involve a troublesome trade-off. While riding a bicycle burns calories and improves cardiovascular fitness, too many hours on a bicycle saddle can compress the artery and vital nerves leading to the penis.
The result? A risk of numbness, pain, and erectile dysfunction.
A male cyclist can place a significant percentage of his weight on his perineum, an area between the scrotum and the anus where the nerves and arteries to the penis pass. This pressure -- and a narrow saddle seat -- can injure the arteries and nerves.
"The earliest warning sign is numbness or tingling," says Irwin Goldstein, MD, director of San Diego Sexual Medicine.
Even a young man may lose the ability to achieve an erection, says Goldstein, who pioneered an operation that restores blood flow and sexual potency in 65%-75% of cases.
How much riding does it take to put a man at risk? The Massachusetts Male Aging Study found that the risk was highest among men who cycled more than three hours a week.
The 'No-Nose' Seat
Goldstein encourages men to sit upright when they ride and replace the traditional bicycle saddle with a "no-nose" seat that redistributes a man's weight to the sit bones of the buttocks.
Serious cyclists who lean forward in a racing position when they ride claim they need the nose to achieve more power and control.
"I don't think you can be a competitive rider and be protected from erectile dysfunction," says Goldstein. "They need that nose between their thighs, and that produces nerve and artery compression."
The evidence that riding a bicycle can be harmful to men is very persuasive, but it should be kept in perspective, says John M. Martinez, MD.
"If someone comes in and says, 'Should I not cycle because of the danger of erectile dysfunction?' I say, 'You have a 50% chance of developing and dying from heart disease, so your primary focus should be exercise and diet -- the two main components of fighting heart disease and ED,'" says Martinez, a primary care sports medicine physician and the medical director at Coastal Sports and Wellness Center, San Diego.
"I wouldn't tell anyone to give up cycling because of fear of ED. If there is ED from cycling, it's almost always temporary and reversible. Other causes of ED, such as hypertension and diabetes -- the No. 1and No. 2 causes of ED -- tend to be fairly permanent. If there are problems, they're usually treatable with proper bike fit and bike seat selection."
A proper-fitting bicycle can help prevent these injuries; appropriate frame size, handlebar height, and seat position are all important. A rider may consider changing the angle of the seat, which should be angled parallel to the ground or slightly forward, to help alleviate pressure on the perineum. Wider seats or those designed with a central cutout also help reduce perineal pressure and can help redistribute weight.
A change in riding style may also help reduce pressure. Standing on the pedals during long rides can prevent pressure and help re-establish blood flow.
Police Bike Patrol Study
Some new saddle designs take the weight off the perineum, according to Steven Schrader, PhD, of the National Institute for Occupational Safety & Health (NIOSH). Schrader triggered an explosion of research on the link between cycling and ED in 2002 when he published a study involving members of a police bicycle patrol. He found that the more hours the officers spent in the saddle, the more likely they were to experience a decrease in the quality of nighttime erections.
All this research spurred the development of several no-nose bicycle seats, and Schrader has tested several.
"We recruited police officers and gave them no-nose seats to use for six months," Schrader says. "We're still doing data analysis, but the striking thing is that of the 91 men who completed the study, only three had returned to a traditional saddle. When we went back and found those three guys, two of them said their saddle had broken and they wanted a new one. Only one said he didn't like it."
No-nose seats have a wide rear that distributes the rider's weight on his sit bones on the buttocks. One study in Germany found that oxygen levels in blood flow to the penis dropped by only about 20% when riders were on a no-nose seat. A traditional bicycle saddle reduces oxygen in blood flow by around 80%.
The Grooved Seat
Bike saddles that feature a groove down the middle or holes in the center to alleviate pressure can actually make the problem worse by increasing pressure on either side of the groove.
"They feel better," Schrader said of the grooved seats. "With the traditional saddle you're sitting on your internal penis. You can feel it. When it drops into the groove it feels better, but if you're increasing the pressure on either side, you're still compressing the artery and the nerves. The wider the seat, the farther back you sit, the better off you're going to be."
The problem affects women too, although not as conspicuously. Schrader recently participated in a study that found the genitalia of competitive female cyclists were desensitized by long hours of riding.
"Some gynecologists say it doesn't hurt their sex life so who cares," Schrader says, "but I say if they're causing physiologic damage, that should be a concern."
Cycling has been commonplace for well over a century. Yet the relationship to ED wasn't widely noticed until 1997 when Ed Pavelka, former executive editor of Bicycling magazine, acknowledged his own erectile difficulties after a year of high-mileage cycling.
Why did it take so long for this problem to come to light?
Actually, it didn't. "Cyclists were talking about numbness in the groin as far back as the 1890s," says Schrader. "Ads used to say that this bicycle saddle is the only one that doesn't cause permanent damage. This has been known about for a long time."
After Pavelka brought the problem to public attention, research has consistently supported the connection between cycling and ED. Yet despite ample research showing that a traditional bike seat and improper cycling position can reduce blood flow and compress nerves, some cycling enthusiasts continue to argue that the health benefits of bike riding outweigh the dangers of ED.
But Schrader contends that evidence to the contrary is overwhelming. True, not every man who rides a bicycle will experience a problem. "One would not expect that every bicyclist would suffer from ED any more than one would expect every smoker would get lung cancer," he wrote in a recent editorial in The Journal of Sexual Medicine. Nevertheless, the time has come to develop effective strategies to reduce this danger. "The health benefits from having unrestricted vascular flow to and from the penis are self-evident," he says.