Cycling has been linked to genital numbness in both men and women, as well as erectile dysfunction (ED) in men. But the use of a seatpost shock absorber could be worth investigation, scientists report.
As bicycles do not have shock absorbers, oscillation forces hit the perineum directly, contributing to micro-trauma and pudendal nerve palsy.
This study looked at the ways oscillation pressures affected male and female cyclists. In addition, it tested a seatpost shock absorber to see if such a device might reduce perineal pressure.
Thirty-nine participants (29 men and 10 women – average age 30) were each fitted to a stationary bicycle in the laboratory. Fifty-nine percent of the participants were recreational cyclists, who cycled at least once a month. Almost a third commuted by bicycle at least once a week.
A pressure sensor was attached to each bicycle saddle. Oscillation was generated by a lever system attached to the trainer. Three stages of force were used with increasing intensity: small medium and large.
Four conditions were tested in 40-second segments by each participant:
• Standard seatpost with no pedaling
• Standard seatpost with pedaling
• Seatpost shock absorber with no pedaling
• Seatpost shock absorber with pedaling
In all conditions, perineal pressure increased with each oscillation increase, and participants experienced higher pressure changes when they were pedaling compared to the stationary stages. For example, when the oscillation was at 1.5g, the pressure increased 19.4% over baseline in a stationary condition and 26.9% in a pedaling condition.
“The implication of this change in pressure is that a 160-lb cyclist who carries 50% of body weight on the perineum will have an increase of 16-21 lb of additional pressure applied to the perineum during every oscillation of 1.5g,” the study authors explained.
They added that rough road conditions could lead to oscillations over 1.5g.
The shock absorber reduced the change in pressure by 57% to 59% in the stationary condition. While pedaling, cyclists also had decreases in pressure changes, but these were not statistically significant. However, the researchers added that “we believe this study provides a significant rationale for future investigations assessing whether the use of a seatpost shock absorber in real-world cycling conditions produces a clinically measurable reduction in perineal numbness and ED.”
The authors also noted that oscillation forces particularly affected “known bony landmarks” in both men and women, which could make them vulnerable to genito-urinary problems.
The study was published online in June in Sexual Medicine.
Sanford, Thomas MD, et al.
“Effect of Oscillation on Perineal Pressure in Cyclists: Implications for Micro-Trauma”
(Full- text. Published online: June 20, 2018)