Groin Numbness and Bike Riding

Author: Richard Weil, MEd, CDE
Medical Editor: Melissa Conrad Stöppler, MD

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.