How does iliopsoas move?
Iliopsoas is not just related to the possible movements we can do; it’s intimately related to our quality of movement. Considered by many the key core postural muscle, our relationship with our iliopsoas influences whether our movements are light, easeful and efficient, or something else.
Because of its location and relationship with other muscles and tissues in the body, there are few actions or activities where iliopsoas is not involved. We’d find it difficult to do even everyday tasks without a functional iliopsoas, since this is the muscle primarily responsible for walking. Let’s look more closely at the relationship between the iliopsoas and movement.
Actions and restrictions of iliopsoas
Anatomically, the iliopsoas:
- Flexes the hip joint (in fact, the iliopsoas is the strongest hip flexor in the body!)
- Externally or laterally rotates the hip joint.
- Assists in lateral flexion of the body (side-bending).
- Extension of the hip joint.
- Internal or medial rotation of the hip joint.
Iliopsoas is one of our primary muscular controls over locomotion - you can’t walk, run, or crawl without involving this muscle.
Remember that the psoas major portion of the iliopsoas spans more joints than any other muscle in the body. It crosses 9 joints: T12–L1, L1–L2, L2–L3, L3–L4, L4–L5, L5–sacrum, sacrum–ilium (SI joint), pubic symphysis, and the hip joint. This means that it can impact indirectly even more movements than it initiates directly.
Just as important as the actions that iliopsoas initiates, is its role in stabilizing the pelvis. It works with other muscles to maintain just the right balance of tension at the pelvis. The iliopsoas works in relationship with its synergists (muscles doing the same action) and antagonists (muscles doing the opposite action) to allow a healthy range of flexion, extension, adduction, abduction, and rotation of the hip joint, as well as anterior and posterior tilt of the pelvis.
Iliopsoas and movement quality
The iliopsoas affects not just the movements that we do - flexion, extension, etc. - but just as importantly, it affects the quality of our movement. It directly impacts the grace and lightness of our movement because of its relationship to our center of gravity. Iliopsoas is one of our primary muscular controls over our center of gravity. It both crosses over and lays on either side of our center of gravity, which is located near the top of our sacrum. Because of its location across our center of gravity, it affects our sense of balance and our sense of being able to move with ease through space.
Iliopsoas and the core
Because of its location and the number of joints it crosses, iliopsoas is a key part of movement from what is often called “the core”. Definitions of which muscles and structures are included in the core vary, but iliopsoas is a central part. We often have an idea, from watching dancers or gymnasts perhaps, that moving from “the core” is an ideal. And, in fact, it does make sense to use our body’s muscular effort to move in a way that is to our own biomechanical advantage.
But how does that work? What would it feel like to initiate movement from iliopsoas?
Exploring your felt sense of movement from iliopsoas
Are you curious to have the experience of moving from the iliopsoas yourself? Try this exercise:
First, take a walk around the room. Don’t try to “do” anything in particular, just walk in a way that feels like your regular walk.
Next, you need to locate your iliopsoas. Review or read: “How to contact your iliopsoas”.
Finally, after finding your own iliopsoas, hold your attention on the area of your body where you contacted your iliopsoas and begin to walk around the room again. Have the intention of directing the movement from deep in the body where you contacted your iliopsoas muscle.
What do you notice? In what ways does it feel different or similar to moving without this conscious intention?