Animation by Anatomography

The pair of psoas muscles link and bend your upper and lower body


By Diane Roberts

Got low-back pain? Check your psoas (that’s SO-as, by the way). Got hip pain? Check your psoas. Got groin pain? Check your psoas. Glute pain? Yep, check your psoas.

What is your psoas? Actually, there are two of them—check the red zones in the illustration. Each is a long, strong muscle that starts in your mid-back, runs down one side of your spine, then curves forward to the front of your pelvis and ends up attached to your inner thigh bones.

As you can see, the psoas muscles connect the back of your body to the front and your upper body to the lower. This dynamic duo is the biggest, strongest member of the muscle group known as hip flexors, which you use to lift your legs, lower your torso, and rotate your hip joints.

Happiness is a healthy psoas
You rely on your psoas to do pretty much anything: walk, run, dance, bike, climb stairs, do sit-ups and down dogs, bend over to hug a kid, lift a foot to put on a sock and, of course, do countless yoga poses. The upshot? If either psoas is unhappy—tight, sore, strained, weak—so are you.

After 25 years of teaching therapeutic yoga, I’d estimate that 98% of the people I work with have psoas issues. Yet almost no one knows what or where the psoas is, or that it’s likely causing their problems. Time to fix that.

How healthy is your psoas? This quick video will tell you and strengthen a weak one
Psoas trouble is often only on one side. In fact, having just one weak psoas is super-common. This imbalance is a frequent cause of a twisted, torqued, or uneven pelvis. That can throw your whole body out of whack and trigger low back, hip, pelvic, and even mid/upper-back pain. The test in my video below will quickly reveal if one psoas is weaker, then give you a simple, gentle way to start strengthening it.

3 video tips
If it’s really hard to keep your heel up during the test, do the easier version every day for a week, then repeat the test. As your psoas gets stronger, you’ll be able to do more and more of the move with your heel up. When you can keep your heel raised throughout the test, continue doing daily leg lifts and add the kneeling lunge from my next blog.

2. If you could pretty easily keep your heel raised throughout the test—or even do the harder version—add the kneeling lunge now.

3. Whenever you’re doing leg lifts or kneeling lunges, always start with your weaker leg, switch to the stronger one, then go back to the weaker leg and do it again, so you always work the weaker leg twice and the stronger leg once.

Soon, your psoas muscles will be strong, flexible, and happy. So will you!