There seems to be lot of “dysfunctional psoas causing back pain” articles. I’d like to offer another viewpoint.
Say a person does have an inhibition in their psoas. What effects would that have on posture?
The short answer is: a general facilitation along the anterior kinetic chain. The body doesn’t like to be in a position it cannot stabilize. If it is weak in an action such as flexion, the body will move more into flexion, which gives the illusion of being in a safe position.
This position then affects the ability of the hamstring to act on the ischial tuberosity. How do you think the lumbar is going to respond when it does not have the reciprocal muscles balancing extension?
The next question that we should be asking is why is the psoas inhibited in the first place? Is that the causation or a symptom of something else?
Lots of questions, and each person has their unique answer.
Looking deeper into causation instead of chasing symptoms is a good practice.
Don’t just treat what you find, look deeper. Peel away the layers.
Ask for next level factors. It could be structural. It could be physiological. It could be emotional/cognitive. There are environmental factors as well as habitual influences that could be in play. How we work and how we move are all considerations as well.
We are complex human beings, not just muscles and a nervous system.
The psoas is involved in posture, stability, and breath. Read more about the “Mighty Psoas” here.