Hamburg, Germany—Serious male cycling enthusiasts might want to consider taking a phosphodiesterase type-5 inhibitor prior to a long ride to prevent pressure-induced hypo-oxygenation of the penis, according to German researchers.
Penile oxygenation decreased by as much as 97% during cycling, a decline that was significantly reduced when men took sildenafil citrate (Viagra), 50 mg, an hour before cycling. The type of bicycle seat used and the rider's position during cycling also affected oxygenation to the penis.
"We concluded that when going for a rigorous bike ride, [male cyclists] should take a PDE-5 inhibitor and also look at the individual saddle, the right saddle, and have the right positioning," said study author Frank Sommer, MD, PhD, a urologist at University Medical Center Hamburg-Eppendorf.
Dr. Sommer became interested in use of PDE-5 inhibitors to improve penile hypo-oxygenation among cyclists when a survey of 1,786 cyclists revealed a two-fold increased rate of erectile dysfunction compared with age-matched non-cyclists. The prevalence of ED increased with age among cyclists and non-cyclists alike, but the difference between groups was consistent across all ages, ranging from 6% among cyclists 30 to 39 years of age (vs. 2.4% among non-cyclists) to 24.5% among cyclists 50 to 59 years of age (vs. 12.8% among non-cyclists).
The findings from the survey provide reason for concern, given that 46% of American adults regularly ride a bicycle and that cycling is a popular sport throughout Europe, said Dr. Sommer.
Cause for concern
"We know from various studies that perineal compression during cycling will decrease blood flow to the penis and cause hypo-oxygenation of the penis, which can cause, over the long term, changes in muscle construction and collagen construction of the penis and [can] result in erectile dysfunction," Dr. Sommer said.
"Other studies have shown that different kinds of saddles have an influence on penile oxygenation during cycling. Different positions on the bike, for example, leaning forward in a 30° position, can tremendously decrease oxygenation due to perineal compression."
To evaluate the impact of a PDE-5 inhibitor on penile oxygenation during cycling, Dr. Sommer evaluated transcutaneous penile oxygen pressure (tpO2) in the glans penis of 13 experienced cyclists. The cyclists were evaluated while riding in a 60° angle sitting position (normal cycling) and in a 30° racing position. Additionally, the cyclists sat on two different types of saddles, one of which had a V-shaped groove in the middle extending from the back of the saddle to about three-fourths of the way to the front.
Each cyclist participated in four evaluations in the crossover study. They rode in the 60°and 30°positions on each saddle and received placebo or sildenafil, 50 mg, 1 hour before each study.
Baseline assessment demonstrated that each cyclist had 100% tpO2 in the standing position. During placebo evaluations with the conventional saddle, penile oxygenation ranged from 3% to 27% of baseline when cyclists rode in the 30°position and from 9% to 39% in the 60° position. During use of the grooved saddle, tpO2 ranged from 19% to 56% when cyclists rode in the 30°position and from 27% to 86% in the 60°position.
When the studies were repeated with sildenafil and the conventional saddle, penile oxygenation ranged between 50% and 82% in the 30°position and between 56% and 89% in the 60°position. Cycling on the grooved saddle was associated with a tpO2 of 77% to 91% in the 30°position and 84% to 105% in the 60°position. Pretreatment with sildenafil significantly increased tpO2 compared with placebo (p<.01).