Men have a tendency to sit with their pelvis tilted backwards. This is an unconscious way of relieving the pressure on the root of penis on the pubic bone, where the nerves and the vessels leading to the genitals are located. When using a two-part saddle chair the lower part of the penis (of which about 9 cm is on top of the pubic bone, below the pelvis, behind the testicles) is not subjected to the same kind of pressure as when using one-part saddle chairs. The harmful compression of the pudendal nerve and vessels can be eliminated almost fully. When the sitting pressure in on the sitting bones (Ischial Tuberosities) the important lymphatic circulation works better.
Men also keep their thighs spread in order to eliminate the feeling of pressure on their testicles; trousers and their middle seam tighten up when men are sitting. In addition, tight clothes keep the testicles too close to the warm body. Sperm production is very sensitive to the rising of the testicular temperature. The two-part saddle chair cools down the testicles to their optimum temperature of 33°C (approx. 91°F). In conventional sitting the temperature of the testicles can often rise to 37°C (approx. 99°F). This is one reason behind the reduced quality of sperm.
For male cyclist the violent pressure on the tissues next to the pubic bone has been proved to cause impotence and testicular cancer. The same phenomenon has also started to occur among men using one-part saddle chairs. A gap in the chair encourages both men and women to tilt their pelvis forward without the uncomfortable pressure against the pubic bone and the genitals. This helps to keep the lumbar posture in the natural lordosis, which is the ideal form of the spine. The two-part saddle chair eases the pressure on the genitals and preserves a safe angle between the thighs and the upper body.