Untangling The Science On Bicycling And Sexual Function

When he started his new bike messenger job in January of 2017, Ryan was excited. He hadn’t cycled since he was a kid, and now, at age 26, he loved being on the move, racing through the streets of Wilmington, Delaware, to get wherever his boss sent him.

But by October, something had gone terribly wrong.

Ryan — who does not want his real name used because of the intimate nature of his problem --  found himself sexually impotent. He had lost all feeling in his penis and testicles. He stopped getting erections.

His general practitioner said it was probably anxiety, but Ryan didn’t believe it.  Mental health problems were the result of his condition, not the reason for it, he said: “The depression my symptoms cause is horrible.”

Finally, when a panic attack landed him in the hospital, a doctor told him the reason for the numbness and impotence could be all his time on a bike saddle.

It had never occurred to Ryan that bicycling could cause this kind of harm. Now, after reading up on the topic and seeing specialists, he’s convinced the bike seat was the culprit.

“It makes total sense when you think about it,” he says. “I mean you’re sitting on a bicycle seat that’s like two inches wide, just putting all that pressure in that area.”

Ryan has learned that genitals are fed by nerves and blood vessels that run through the perineum, the area between and in front of the sit bones, and that they can be squashed by pressure on a bike seat, ultimately disrupting sensation and blood flow to sex organs.

Almost a year after his symptoms began, Ryan had a nerve operation that allowed him to regain some feeling, but it's still unclear if he will ever fully recover. “If I had known what could happen, I might have ridden the bike once a week, not every day,” he says. “People who are doing excessive bike riding should be aware somehow, but there is no warning for those people.”

'The Unseen Danger?'

Not only is there an absence of warnings, but media have sent the opposite message. A recent headline in Outside Magazine reassures readers: No, Bike Saddles Won’t Destroy Your Sex Life. A Bicycling Magazine headline tells men, Cycling Won’t Kill Your Erection, and another says to women, Cycling Can Boost Your Sex Life.

These articles are based on credible science, including two recent studies from the University of California San Francisco  – one on men and one on women – that surveyed thousands of online respondents and concluded that bicyclists’ sexual function is no worse than that of swimmers or runners.

But these studies follow decades of research that indicated the opposite, backing up what Ryan believes happened to him.

So why would anecdotes and scientific studies so starkly contradict one another?

The question of a link between cycling and sexual dysfunction entered into public discourse in 1997. A Bicycling Magazine article warned of “the unseen danger” for male cyclists. The piece profiled men who blamed their erectile dysfunction on cycling, and quoted Dr. Irwin Goldstein, a urologist and outspoken believer in the bike seat-dysfunction link.

Goldstein told Bicycling Magazine that he treated an average of six cyclists a week who had erectile dysfunction. He said he couldn’t prove that sitting on a bike seat causes impotency, but he appealed to logic with this analogy: “[It's] intuitive that if you took a straw and sat on it, a certain percentage of the time the straw would jump back and be a circular structure. But if you keep doing this, at some point the straw is going to take on a sort of oval shape [or flatten].”

Though unlike straws, Goldstein acknowledged, most cyclists' sex organs will not develop problems.

Several scientific journal studies bolstered Goldstein’s claims.

A 1997 survey of cyclists in a long-distance race in Norway found that 2 percent reported persistent impotence more than a month after the ride. A smaller but oft-cited 2002 study found that bicycling policemen were significantly less likely to get erections during their nighttime sleep than non-cyclists.

A 2006 study showed a decrease in genital sensation among competitive women cyclists, and others have indicated that, similar to the mechanics of cycling-induced male erectile dysfunction, perineal arterial compression can stop clitoral engorgement. Doctors report seeing women cyclists who have increased difficulty achieving orgasm, and some elite women cyclists complain of long-term labial swelling.

Disparate Findings, Disparate Answers

The two recent UCSF articles refuting the link between cycling and sexual dysfunction argued that previous studies asserting that link were inadequate because they had used small sample sizes and had not employed validated measures.

Outside Magazine’s self-described “Bike Snob,” Eben Weiss, went so far as to say those past assertions of a link were mythology, “fear mongering,” and part of “a vast anti-bike conspiracy.”

To Dr. Roger Minkow, the old studies and the new are both right. There used to be a problem, he says, and now there isn’t one. But this take is also good marketing: After the ’97 Bicycling article, Minkow designed and successfully promoted bike seats for Specialized that he said reduced cyclists’ risk of developing ED.

Many of his saddles feature cut-outs in the middle to relieve pressure on part of the perineum. A number of journal articles have found that cut-outs, while often more comfortable and sometimes recommended by doctors, can actually increase the risk of problems like uneven perineal pressure, numbness and decreased oxygenation. Minkow says those studies look at older cut-out models than his.

Dr. Ricardo Munarriz, who heads the Boston Medical Center’s Center for Sexual Medicine, rejects Minkow’s assertion that things have gotten better. He says he’s seen no decrease in patients with cycling-related sexual dysfunction.

“Bicycle riding has been shown to be a risk for erectile dysfunction in case reports, in case theories, in control studies, in population-based studies, and in mechanistic studies,” he says. “I mean, the evidence is there.”

Dr. Goldstein sees flaws in the UCSF studies, which surveyed thousands of respondents contacted through Facebook and sports club Websites. He says the authors have “no idea who's participating in the trial ... and not one person was spoken with.”

Besides, Goldstein says, “you're never going to convince me that bicycle riding doesn't cause impotence because I see it [in patients] all day.”

The UCSF articles acknowledge certain limitations, including that the researchers did not follow people over time. The study of women points out the possibility of "survivor bias," meaning that someone who experienced sexual dysfunction might quit biking because of it and therefore wouldn't participate in the study.

Dr. Ajay Nehra, a urologist at Massachusetts General Hospital, calls the UCSF study on men “one of the most compelling studies out there right now.” Still, he says, the question of a bike-dysfunction link is not settled, and more longitudinal studies need to be done.

He says the only bike labs he’s aware of are backed by bicycle manufacturers, so “there’s a bias in those labs [in favor of] speed, comfort, ease, commercialization.” As far as his own observations, Nehra says it’s hard to tell if erectile dysfunction in his patients is a result of bicycling or something else, since dysfunction can stem from so many conditions.

Why Some And Not Others?

Perhaps the best way to reconcile the apparently contradictory findings is this: There clearly are people who suffer severe sexual dysfunction after spending many hours on a bike saddle, but they appear to be a very small minority, easily missed by some studies.

One reason a minority of cyclists may suffer sexual side-effects is poor fit. As a general rule, higher handlebars are considered safer. So are wider seats. But many long-distance cyclists with low handlebars and narrow seats will be fine.

One way to understand it is “the analogy that we sort of laugh about,” says sports and science journalist Joe Lindsey. “Butts are like snowflakes. There are no two that are alike.”

Someone with wide sit bones might experience more pressure on soft tissue if they’re on a narrow seat. Determining that width involves actually measuring, rather than just observing, says Dr. Andy Pruitt, who founded a sports medicine center in Boulder, Colorado. He also consults with Specialized, and is now working with several elite female cyclists to design a better saddle for women.

“You can’t judge a book by the cover,” he says, meaning that one’s gender and appearance are not enough to tell “a teenager working in a bike shop” how far apart those bones are and therefore which saddle to recommend.

Pruitt says it’s easy for stores to measure the width using memory foam or digital devices – though he believes most stores don’t.

Other risk factors, Pruitt says, involve the shape of one's pelvis (how much it is inclined to rock forward) and how deep in the soft tissue one's nerves and arteries lie.

What You Don't Feel

To be safe, some doctors simply advise cycling in moderation. But if you really want to do those century (100-mile) rides, you can look out for a sign. It’s not discomfort. It’s what you don’t feel.

Although respondents to the UCSF studies did not report sexual dysfunction more than other athletes, they did report genital numbness at higher rates. Dr. Pruitt says that’s a bad sign because it signals irritation of nerves that lie alongside blood vessels.

“If you're getting numb, I guarantee you you're also crushing the artery,” he says. “The collapsing of the artery in the long term leads to scarring of the artery," which could mean “blood flow gets impeded and you've got some degree of erectile dysfunction.”

To avoid numbness, the UCSF researchers advise spending a lot of time standing up on long rides. Doctors say if numbness persists, you should change your seat or adjust your bike fit.

In a growing industry, bicycle manufacturers, sellers, and consumers are on an ongoing quest to find a balance between safety and performance.

Some are going all out for safety.

When I ask Dr. Goldstein about the backlash he’s faced from defenders of bicycling – people who call him anti-cycling – he surprises me with his response: “I bike every day of my life,” he says. “Bicycling is a fabulous sport. I mean you get out there, you sweat, you get to see things. It's really fun.”

But he does so on a mobile elliptical machine that allows him to move on wheels without sitting on a seat. He says biking today is great because there are safer options, which include recumbent bikes and regular bikes with noseless saddles.

“I'm not going to risk my perineum while riding,” he says. “There's no way.”

Readers, thoughts? Experiences? Please share in the comments.

Amy Bracken (amybracken2003@yahoo.com) is a Boston-based freelance reporter and radio producer. She tweets @brackenamy.