Groin Numbness and Bike Riding

Author: Richard Weil, MEd, CDE



Bike riding is terrific aerobic exercise, a healthy and economical way to commute, and a great way to run errands, sightsee, and get around town. There is, however, a potential downside to biking; sitting on the bicycle seat may result in the compression of nerves and blood vessels of the vulnerable area of the body called the perineum. The perineum is the area between the anus and the base of the penis in males and between the anus and the vagina in females; it contains both blood vessels and nerves. Compression of the perineum can lead to nerve damage, swelling, artery insufficiency (lack of blood flow through the vessel), and even occlusion (blockage) of blood vessels, which in turn can lead to temporary or permanent groin numbness, tingling sensations, decreased penile blood supply, erectile dysfunction (impotence), decreased orgasm sensitivity, and pain. These cycling-related perineal symptoms are the subject of this article.

How common are cycling-related perineal symptoms?

In a study of perineal compression and blood flow to the penis in male cyclists, penile blood supply decreased significantly in 70% of the 40 cyclists who participated in the study. Numbness in the genital area was reported by 61% of the cyclists, and 19% of the cyclists who rode their bikes more than 250 miles per week complained of erectile dysfunction.

In a study of 463 cyclists competing in a long-distance cycling event (200 miles), perineal numbness during the ride was experienced by 31% of the cyclists and was associated with erectile dysfunction that lasted as long as one week after the event.

In a study called a meta-analysis (where many studies on the same subject are summarized), results of 35 studies conducted between 1981 and 2004 that examined the relationship between cycling and erectile dysfunction showed that the prevalence of moderate to severe erectile dysfunction in bicyclists was 4.2%, and that riding more than three hours per week was a risk factor for developing this condition.

In another meta-analysis investigating perineal symptoms and cycling (62 articles), numbness of the genitalia was reported in 50%-91% of all cyclists, and erectile dysfunction was reported in 13%-24% of all cyclists.

Perineal symptoms are not experienced by all cyclists, but this is certainly something to be aware of, particularly if you plan to ride long distances.

What are factors that cause perineal symptoms? The interaction between the bicycle seat (saddle) and the perineum is the culprit in all cases of perineal symptoms in cyclists. The interaction is dependent on the vertical (downward) and shear (backward) force of the perineum on the saddle, the weight of the rider, the height and angle between the saddle and the handlebars, the saddle tilt angle, and the shape of the saddle. Below is a review of these factors.

Weight loading

Vertical loads of the perineum to the saddle can be as high as 52% of the rider's body weight, whereas shear loads can reach 12% of body weight. The vertical pressure is dependent on the rider's body weight as well as riding position. Although there is no conclusive data as to what degree of load increases the likelihood of symptoms, there does appear to be a relationship between load stress and compression of the perineum.

Saddle and handlebar height

In a study of erectile dysfunction and bicycle characteristics, researchers determined that keeping handlebar height lower than saddle height in long-distance cyclists was associated with less erectile dysfunction, perhaps because this configuration puts the rider in a leaning-forward position which may reduce vertical load on the perineum. This position may or may not apply to recreational riders on touring or hybrid bikes where speed and aerodynamics are not as important, but there is no research to support the claim one way or the other.

Saddle angle

In three studies of the angle of the saddle, it was confirmed that a downward tilted saddle reduced stress and compression on the perineum. This is probably because the backward stress puts the weight of the rider on the ischial tuberosities (the "sit bones" in your buttocks) and off of the perineal cavity.

Saddle shape

Bicycle saddle design has been the target of a great deal of scholarly and commercial research. A number of years ago, bicycle saddles started to be manufactured with cutouts down the middle with the hope that this would relieve pressure on the perineum and reduce compression symptoms. Indeed, in one study, 55% of the subjects ranked the partial cutout saddle as the most comfortable. In a recent study of a new saddle (Selle SMP) with a large cutout and downward facing nose (the front of the saddle), the saddle was clearly superior in preventing vascular compression and penile blood flow occlusion compared with more standard saddle designs.

Interestingly, in a study on saddle shape and penile blood flow, a narrow saddle was associated with greater reductions in penile blood flow than a wider saddle, leading the researchers to conclude that the narrow saddle could be a source of blunt perineal trauma. In a study involving computer analysis of forces on the perineum with wide and narrow saddle design, it was also shown that a wide saddle capable of supporting the sit bones was superior for reducing perineal stress compared with a narrow saddle. Most racing saddles, however, are narrow, and this may have some effect on perineal symptoms for some riders. In a study of a saddle without a nose compared to a traditional saddle with a protruding nose, the traditional saddle was associated with two times greater perineal pressure than the noseless saddle. These results have been confirmed by another study. However, it has been reported by riders that noseless saddles lead to a feeling of less control over the bike since their thighs are not fully in contact with the saddle. More research needs to be done on optimal width and shape of the saddle.

Should I buy a gel seat cover?

There's no evidence that a gel seat will help reduce perineal symptoms. In fact, in some cases, too soft a seat can cause more discomfort than a slightly firmer saddle (sort of like how too soft a mattress can lead to back pain). A gel seat may work better for short-distance riding like errands or commuting, but it might not work as well for longer rides because it lacks stability and support.

The search for the perfect saddle is elusive. What may work for one rider may not work for another. So many factors are involved that it is unlikely one saddle will work for everyone. The conventional wisdom in the biking world is to experiment with saddles until you find the one that works best for you.

Can women get perineal symptoms?

Yes. In a study of 282 female members of a cycling club, 34% reported perineal numbness. The researchers pointed out that this is due to the fact that certain parts of the female and male anatomy are similar, particularly the vessels and nerves in the perineum.

Can I get perineal symptoms from spin class?

I am not aware of any research that addresses this question, but it makes sense that you could be at risk since spinning isn't different than outdoor biking in terms of pressure on the perineum. With that in mind, make sure to adjust your seat height properly (ask your instructor if you're not sure how), and wear bike pants to cushion the perineum from saddle forces.

What can be done to prevent perineal symptoms?

The variables that contribute to perineal symptoms during biking are complicated, and so it may be that you need to experiment with different strategies until you find the right one for you. Here are a number of suggestions that may help reduce the risk of perineal symptoms.

1. Stand up frequently on the pedals to take pressure off the perineum. 2. Change your position on the saddle while biking. Shift forward and backward when you ride to eliminate pressure on just one part of the perineum. 3. Experiment with adjusting the angle of your saddle so that it tilts slightly downward. 4. Wear bike shorts. They have chamois padding in the perineal area that will help relieve pressure. 5. Adjust the height of your handlebars slightly until you find a comfortable position. Handlebars below the saddle may work well for road or racing bikes, but perhaps not as well for touring or hybrids. 6. Make sure that your seat post is adjusted to the proper height. Your knee should be just slightly bent at the bottom of the pedal cycle. 7. Limit the number of miles that you pedal. This may not be desirable for all riders, but number of miles per week can be a factor.

The final word

Many factors can contribute to perineal symptoms, and you will need to experiment with all of the factors mentioned in this article if you do experience them. Of course, just because you bike doesn't mean that you will experience perineal symptoms; in fact, many cyclists ride for years and never experience any of them. But if you do, and they continue after you make adjustments in your bike or riding style, then see your doctor because they probably won't get better on their own if you continue to bike. In most cases, perineal symptoms are not permanent and can be treated successfully.