UroToday.com- Bicycle riding has been linked to an increased risk of erectile dysfunction (ED) and abnormal perineal sensations in male riders, which are postulated to result from compression of the internal pudendal arteries and/or the pudendal nerves. Bicycle seat manufacturers have responded with a variety of seat designs intended to reduce the potential for pudendal artery and nerve compression. The objective of a recent study by J. M. Gemery, S. K. Reid, and colleagues from Boston University was to create digital three-dimensional (3D) models of a pelvis, pudendal arteries and bicycle seats to evaluate the potential sites of compression of the vessels. The study is published in the January 207 issue of BJU Int. The authors hypothesized that the seat type in conjunction with the rider's position differently affects the orientation and compression of the pudendal arteries. After using 3D models of one male pelvis and three bicycle seats, the authors then correlated with lateral radiographs of a seated rider to determine potential vascular compression between the bony pelvis and seats at different angles of rider position. Penile hypoxia secondary to decreased blood flow might be injurious, and has been postulated to promote trabecular connective tissue synthesis, which could impede the achievement of erection. There have been studies that have shown a decrease in mean transcutaneous penile oxygen pressure at the glans from 60.5 mmHg, standing before cycling, to 17.9 mmHg after 15 minutes of cycling while seated. Analysis of the results showed that the most likely site of compression of the internal pudendal artery is immediately below the pubic symphysis, especially with the rider leaning forward. For an upright rider, the pudendal arteries do not appear to be compressed between the seat and the bony pelvis. Leaning partly forward with the arms extended, the space between the seat and the symphysis areas were reduced to 73 mm2 with a narrow racing seat compared to 259 mm2 with a grooved seat. When leaning fully forward there was potentially no space between both the pubic symphysis and the ischial tuberosities and the narrow racing seat. With the grooved seat, the space was 51 mm2. This is a small improvement over the standard seat but it shows that rider position can nearly eliminate the improvements that the grooved seat provides. John M. Gemery, Ajay K. Nangia, Alexander C. Mamourian and Scott K. Reid BJU Int. 2007 Jan; 99(1):135-40 Reviewed by UroToday.com Contributing Editor Michael J. Metro, MD UroToday - the only urology website with original content written by global urology key opinion leaders actively engaged in clinical practice. To access the latest urology news releases from UroToday, go to: