August 17, 2012
By Harvey B. Simon, M.D.
Harvard Medical School
Exercise protects against heart disease, high blood pressure, stroke, diabetes, certain cancers, depression, dementia and obesity. It also increases bone calcium and muscle strength. When performed regularly, exercise prolongs life while adding vigor and enjoyment to those extra years.
Perhaps it's the extra vigor that leads some athletes to claim that exercise has also improved their sex lives. More than one runner has been spotted wearing a T-shirt boasting "Marathoners Keep It Up Longer."
Biking is an excellent form of exercise. It shares the benefits of walking, jogging, swimming and other aerobic activities. But bikers don't generally boast about their sexual prowess. On the contrary, many worry that their favorite sport may, in fact, damage their reproductive organs and sexual function.
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The Anatomy of Man and Bike
When a man sits on a chair, his weight is distributed across both buttocks; the two ischial bones of the pelvis absorb a lot of that weight. This takes the pressure off the perineum, the central zone that contains the nerves and arteries that run into the penis. But because a bicycle seat is narrow, it places pressure on the perineum itself, compressing crucial nerves and arteries.
Nerve damage accounts for the penile numbness bikers experience. Pressure on the pudendal artery adds to the nerve injury to produce erectile dysfunction, which can be temporary or prolonged. A narrow bike seat can reduce blood flow by as much as 66%, and even a broad seat may temporarily reduce flow by 25%.
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What the Research Shows
Over the years, urologists have treated bikers with erectile dysfunction. Over the past 10 to 15 years, many studies have given scientific heft to these observations. Here are a few examples.
Doctors in Norway evaluated 160 men who filled in a questionnaire after they participated in a bike tour of some 324 miles. That's a long way to ride, especially in competition. And it produced a surprisingly large number of urological complaints.
- More than one-fifth of the men experienced at least one symptom.
- Twenty percent of those men had numbness of the penis, which lasted more than a week in more than six percent of the riders.
- Thirteen percent (21 men) had impaired erectile function (ED), which lasted more than a week in 11 men and more than a month in 3 men. That's a high price to pay for fitness, even with the glory of a championship race thrown in.
The Norwegian experience may be extreme, reflecting the effects of very prolonged biking under intense conditions that might lead a rider to ignore warning symptoms. But it's not an isolated finding.
To find out if urological symptoms are related to the distance a man rides and the time he spends perched on his bike, doctors in Boston surveyed 505 members of a biking club and 126 male runners who didn't ride at all. They found that the more a man rides, the more likely he is to develop urological complaints, including penile numbness, pain, altered ejaculatory sensation, difficulty achieving orgasm, impotence and urinary complaints.
Researchers from the National Institute for Occupational Safety and Health evaluated 17 members of a bicycling patrol unit in Cincinnati, Ohio. The men averaged nearly 5½ hours in the saddle each workday, and 91% experienced genital numbness from time to time. More significantly, when the members of the patrol underwent testing, they showed fewer nighttime erections than volunteers who did not ride bikes. The men who rode the most were at the highest risk for erectile dysfunction. In addition, the researchers found that the men who put the most pressure on their bike seats had the most problems.
Do you have to give up biking to preserve your sexual function? No! In fact, you can break the vicious cycle of biking and sexual dysfunction by taking a few simple precautions.
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- Don't use a racing seat with a long narrow nose. Pick a wide seat, ideally with plenty of padding. Special gel-filled and shock-absorbing seats are even available.
- Don't tilt your seat to the forward position. This increases pressure on your perineum.
- Be sure the seat height is correct. Your leg should not completely straight at the bottom of your pedal stroke.
- For extra protection, consider wearing padded biking pants.
- Raise the handlebars so you are sitting more upright.
- To protect yourself from trauma to your genitals if you fall against the bike's top tube, put some foam padding across it.
- Be sure the top tube is at least two inches below your crotch when you stand straddling the tube or look for a bike with a slanting, or step through, top tube (a "woman's bike").
Above all, be alert for early warning symptoms. If you experience tingling or numbness in your penis, get off your bike. If the problem recurs despite a broad, padded, well-positioned seat, consider switching to a recumbent bike, especially if you are a heavy man.
Even if you don't develop warning symptoms, shift your position and take breaks during long rides. And while you're at it, be sure to protect the rest of your body from biking injuries:
- Wear a helmet.
- Ride defensively and prudently while obeying the rules of the road.
- Avoid hazardous weather conditions.
- Wear bright, highly visible clothing.
- Beware of the biker's arch enemies: cars and dogs.
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Balance Is the Key
Perhaps the best advice of all is to make biking part of a balanced fitness program instead of relying on it exclusively.
Alternate riding with walking, jogging or swimming. Climb off your stationary bike and get on a treadmill, elliptical trainer or stair climber. Make exercise part of your daily life; if biking is your thing, exercise the simple precautions that will enable you to keep it up longer.
Andersen KV, Bovim G. "Impotence and nerve entrapment in long distance amateur cyclists." Acta Neurol Scand. 1997; 95: 233240.
Schrader SM, Breitenstein MJ, Clark JC, Lowe BD, Turner TW. "Nocturnal penile tumescence and rigidity testing of bicycle patrol officers." Journal of Andrology. 2002; 23:927934.
Sommer F, Goldstein I, and Korda JB. "Bicycle riding and erectile dysfunction: a review." Journal of Sexual Medicine. 2010; (7)23462358.
Harvey B. Simon, M.D. is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.