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Gov't Study on Cycling and Sexual Dysfunction(7 posts)

Gov't Study on Cycling and Sexual Dysfunctionjontrapp
Oct 21, 2002 12:43 PM
I used to work for NIOSH (National Institue for Occupational Safety and Health), a part of the CDC.
They sent this e-mail out this morning and I thought that people might find it interesting.
I know this topic has been discussed into the ground, but the findings were interesting


Attached FYI is an Oct. 18 NIOSH Update that provides information to the press, public, and other stakeholders about a NIOSH study which found an association between pressure from certain bicycle saddles in prolonged job-related bicycling and a decrease in a measure of reproductive function among a group of police bicycle-patrol officers. Also attached is a "Wall Street Journal" article from earlier this week that mentioned the study. Steve Schrader in DART is the project officer.


October 18, 2002



Pressure on the perineum, the area behind the scrotum, from prolonged bicycling was linked with a decrease in a measure of erectile function among a group of police bicycle-patrol officers, the U.S. Centers for Disease Control and Prevention's (CDC) National Institute for Occupational Safety and Health (NIOSH) reports in a new study.

The long-term implications of the finding are unknown, and there was no evidence of impotence in any of the officers. As a precautionary measure, NIOSH recommended several ways in which the police department and patrol officers could decrease potential risk. It is not possible to use the study to predict whether the same results would be found for recreational and competitive bike riders, because key factors would differ.

The study, which will be published shortly in the November 2002 issue of the Journal of Andrology, was prompted in 2000 by concerns about genital numbness among officers in the Marine Bicycle Patrol, Long Beach, Calif. NIOSH surveyed the officers, measured the pressure caused by their weight on their bicycle saddles, evaluated blood hormone values, and assessed penile function by using electronic sensors to monitor erections while the officers were sleeping, a scientifically accepted method for evaluating male sexual function. Some limitations in the study, such as the small number of persons studied, constrain the ability to draw definitive conclusions.

The study found that:

* The officers had erections for less time during sleep than a comparison group of men who did not ride bicycles occupationally.

* The decrease in that measure of erectile function, and the occurrence of genital numbness, was associated with the pressure on the perineum area behind the scrotum created by the projecting "nose" of the saddle.

* The officers' blood hormone levels were normal.

Among other precautionary measures, NIOSH suggested that the city consider purchasing bike seats without noses, to reduce prolonged pressure on the perineum, and that officers dismount from their bikes when not riding. NIOSH provided its findings to the International Association of Machinists and Aerospace Workers, Local 1930, which represented the officers and which requested the study, and to the city police department.

NIOSH will make the study available on its web site. The report to the union and the city, originally issued in 2000, is available on the web site at . For information on other NIOSH studies on occupationally related male and female reproductive health issues, visit the NIOSH web page at or call NIOSH toll-free 1-800-35-NIOSH (1-800-356-4674).

October 15, 2002


How big was their sample group.Sintesi
Oct 21, 2002 12:52 PM
Just how many guys did they get to sleep with boner measurers on their weezers anyway? I'll bet a dozen. Cops? C'mon, these people are not "cyclists." What was their control group?

Don't scare me like that.
LOLOLOLOL!!!! nmNo_sprint
Oct 21, 2002 1:12 PM
How big was their sample group.jontrapp
Oct 21, 2002 2:56 PM
I agree with you that the cops aren't indicative of "true cyclists", but I thought there might be some interest in the report anyway.
Also, it's possible that there are spurious variables that were not accounted for (perhaps the cops don't wear bike shorts, etc).
As for your questions regarding sample size, here's the summary page from the actual report:

In May 2000, the National Institute for Occupational Safety and Health (NIOSH) received a request for a
health hazard evaluation (HHE) from a representative of the International Association of Machinists and
Aerospace Workers (IAM) Local 1930. The health concerns were genital numbness, sexual dysfunction,
and feet problems in the Marine Bicycle Patrol, Long Beach Police Department, Long Beach, California.
From July 10 to 22, 2000, NIOSH researchers visited the City of Long Beach, California, to evaluate the
Marine Bicycle Patrol officers and the possible health effects associated with biking. Twenty-nine biking
officers participated in at least part of the study. Five non-biking men from the Long Beach area were used
as the comparison group.
Fourteen of the fifteen (93%) bikers responding to questions on genital numbness indicated that at times they
experienced numbness in their buttocks, scrotum, testicles, or penis during or after riding their bicycles. This
numbness occurred after 10 minutes to 3 hours of riding and lasted from 5 minutes to 24 hours.
Blood hormone levels and semen quality were normal in the officers providing samples.
The male study participants were asked to wear a Rigiscan® erection monitoring device for 2 nights. The
number of sleep erections was not affected indicating the basic neurophysiology of erectile function was
intact in biking officers. However, measures of erection quality were lower in the biking officers. The
percent of the sleeping time a man had an erection was statistically reduced (p=0.0097) in the biking police
(26.2%) compared to men (42.8%) not riding bicycles. As the measured pressure between the officer and
the bicycle seat increased, the percent sleeping time the individual had an erection was decreased. Similarly,
as the average number of hours per day an officer was on his bike and the average number of days a week
the officer rode his bike increased, the percent sleeping time with an erection decreased.
Just a few guesses hereKerry
Oct 21, 2002 4:38 PM
1. As noted by other posters, one can guess that there are not many subjects in this study.

2. With a small sample size, it's virtually impossible to control for all the other things that might cause this.

3. In fact, bike cops spend very little time actually sitting on the saddle compared to what a roadie might do.

4. Any chance that these cops, by virtue of getting more exercise than the general population, sleep more soundly and therefore get fewer "episodes" per night?

5. Did the study compare with people who got comparable exercise, but not on bikes? Of course not!

The technical term for studies like this is "junk science" and the recommendations by the authors are specious at best.
One theory is as good as anotherChainstay
Oct 21, 2002 7:10 PM
The bike riding cops are more attractive to women and have more frequent sex. While sleeping at night, they have fewer erections because they are less frustrated.
I suppose, as a rebuttal, we could all......joekm
Oct 22, 2002 5:45 AM
post pictures of our erections.

....perhaps that's for another forum though.......