SI Joints: Function: Sacroiliac / SI Joints Anatomy, Pain & Issues


The SI joints are weight-bearing. They transfer and distribute the weight of the torso to the pelvis and legs.

  • They provide “shock absorption and transfer of torque during [walking].” (Ray Long MD)
  • “When we walk, [they] help to transmit the force of the impact of our steps upward and diffuse it.” (Amber Burke)

Degree of Movement

  • The ligaments permit some movement in children and healthy young adults and restrain movement in most people over the age of 25.
  • Hormones loosen ligaments during pregnancy to permit passage of the baby.

Involved in Every Yoga Pose

The sacroiliac joint (SI joint) is involved in literally every yoga pose we practice. It is the hub for the transference of force between the legs and torso.  – Ray Long, MD

Transfer Load & Distribute Forces

The SI joints serve to transfer the load of the upper body to the lower body, as well as to distribute forces moving up the body from below. Therefore, stability is built into their very design so that these forces can be transferred efficiently through the pelvis. In fact, the SI joints are so inherently stable that there is only the tiniest amount of movement available at these joints. – Jenni Rawlings,