The sacroiliac joint (SIJ) connects the sacrum to the ilium. It is stabilised with strong ligament and capsule structures. Because of this pronounced stabilisation, it is also known as an "amphiarthrosis" - which translates as "tight joint".
The movements of the sacroiliac joint influence the width of the pelvis, which is why the joint is so important for women during labour.
Road cyclists often have problems with the sacroiliac joint due to their bent-forward posture on the bike: this posture causes shearing forces that can even lead to dislocations or blockages of the joint. In contrast to a normal joint, the sacroiliac joint is not moved directly by muscle action. The numerous ligaments and muscles that surround the joint can nevertheless influence its position incorrectly. It is therefore particularly important not only to regularly strengthen the entire pelvic and trunk musculature, but also to stretch and mobilise it.
