The Psoas Muscle: How One Tiny Hip Flexor Affects Your Stress, Breathing, and Back

That's Pso(as) Cool - a deep dive on the most underrated muscle in your body.

When it comes to muscles, there's nothing I like more than getting nerdy and helping people connect the dots between their anatomy and their physiology. The psoas is the perfect muscle for this, and honestly, one of the most important muscles you've probably never thought about.

It's a spine stabilizer. It's a hip flexor. It plays a starring role in your stress response. And if you sit a lot, stress a lot, or both, there is a good chance your psoas is asking for some attention.

Let's dig in.

What Is the Psoas Muscle?

The psoas, pronounced so-az, the p is silent, attaches to the vertebrae of T12 through L5 and to the inner part of your hip called the lesser trochanter.

That makes it the only muscle that directly connects your spine to your leg, which means it can influence the biomechanics of both. Again, kind of a big deal.

What Does the Psoas Muscle Do?

Its actions depend on whether your leg is fixed or free to move through space, but the psoas is capable of a lot:

Hip flexion
Hip external rotation
Hip abduction
Anterior pelvic tilts
Lumbar spinal stabilization, including compression and stiffening
Trunk flexion

It helps us stand. It provides balance and tone to the spine. And it plays a major role in walking, generating significant force throughout the gait phase to keep your movement efficient.

Basically, it's involved in almost everything we do as humans.

How Does the Psoas Affect Breathing?

This is where the nerdiness really sets in.

Diaphragmatic breathing directly influences how the psoas holds tension, and psoas tension can restrict diaphragmatic breathing. The reason? The psoas attaches to the same spinal levels as the diaphragm in the thoracic and lumbar spine.

They're neighbors. They talk to each other. When one is unhappy, the other usually is too.

Why Is My Psoas So Tight?

The psoas often gets a bad rap for being tight, but a lot of times that tightness is actually weakness in disguise.

Weakness can come from:

Being in a prolonged shortened position, like sitting all day. When a muscle is constantly shortened, it can't generate as much force overall, which leads to it getting weaker and weaker.
Neuromuscular inhibition, your nervous system dialing the muscle down.
Overcompensation for other weak muscles around it.

So if your psoas feels tight, the answer isn't always to stretch harder.

How Does the Psoas Affect Your Stress Response?

Here's where things get really interesting.

If you've ever heard the phrase, "I carry my stress in my hips," the psoas is usually the complicating factor.

When we go into sympathetic response, aka fight or flight, the psoas is one of the primary muscles that contracts. Why? Because we need it both for running away and for curling into a fetal position to protect ourselves. It's present for both the fight and the flight.

And let's be honest, the world we live in offers plenty of opportunities to be in fight-or-flight mode.

If you're in chronic sympathetic overdrive, this muscle stays partially contracted, which can lead to:

Tension and pain through the hip and low back
Increased compression in the spine and hip joint
Restricted slide-and-glide through those joints, which we definitely want to move freely
Dysfunction in the SI joint and pelvic floor

This is also why emotions can come up when this muscle finally releases. If you've ever teared up during pigeon pose in yoga, that's exactly what I mean.

How Do I Know If I Have a Tight Psoas?

There are a bunch of ways to test for psoas tightness, but here's a simple one you can do at home:

The lying-flat test: Lie flat on your back on the floor.

Your knees should feel pretty snug to the ground, unless you have a history of knee issues.
Your lower back should feel like it can relax into the floor.

If your knees are significantly lifted, or your lower back is heavily arched, that can be an indication of a tight psoas.

How Do You Release a Tight Psoas?

This is where I get a little particular.

I have a psoas positional release video on YouTube that walks you through my preferred technique. I like positional release more than aggressive manual techniques because we often need to work with the nervous system to get this muscle to relax, not bully it into submission.

Stretching hard or having a massage therapist dig into your psoas can be uncomfortable, and often it doesn't give your nervous system the input it needs to feel safe enough to let go.

That said, you can still target this area effectively with:

Stretching
Strengthening
Dry needling
Myofascial release

as long as your nervous system is getting the proper care and attention along the way.

My Suggested Starting Point for a Tight Psoas

Try the psoas positional release.
Follow with diaphragmatic breathing to down-regulate your nervous system and help the area ease.

Give this muscle a little love. It does a lot for you.

Psoas FAQ

How do you pronounce psoas? So-az. The p is silent.

Where is the psoas muscle located? It runs from the vertebrae of T12 through L5 down to the lesser trochanter on the inner part of your hip. It's the only muscle that directly connects your spine to your leg.

Can a tight psoas cause back pain? Yes. A chronically tight psoas can increase compression in the lumbar spine and contribute to low back pain, as well as SI joint and pelvic floor dysfunction.

Why does releasing the psoas make some people emotional? The psoas is heavily involved in the fight-or-flight stress response. When it finally releases, stored physical tension, and sometimes stored emotion, can come up with it.

Is psoas tightness always from weakness? Not always, but often. A muscle held in a shortened position, like during long hours of sitting, can lose strength over time, and that weakness can present as tightness. Neuromuscular inhibition and overcompensation patterns can play a role too.

Is stretching enough to fix a tight psoas? Sometimes, but not usually on its own. Because the psoas is so connected to the nervous system, the most effective approach combines release work, breathing, and sometimes strengthening, not just stretching.

Do you have a tight psoas?