Back Pain – PSO What???


The psoas is a rope-like muscle located deep in the stomach, which runs obliquely from the spine to the femur. The psoas is joined at the hip, literally, by the iliacus, which runs from hip to thigh. Together, the psoas and iliacus make up the iliopsoas–the body’s most powerful hip flexor.

Why should runners care about a hard-to-find muscle with an unusual name? The psoas is the muscle that enables you to run.  When you lift your knee, the psoas contracts. When your leg swings back, the psoas lengthens. For a runner averaging 180 strides per minute, the left and right psoas each contract and lengthen more than 5,000 times during the an hour run. That’s a lot of stress and strain on a band of muscle that’s only about as thick as your lower forearm.

The psoas also promotes good posture. Along with a coordinated team of core muscles–abs, obliques, lower back–the psoas helps stabilize your midsection and pelvis. Every time you stand, walk, or run, you’re engaging the psoas. If the muscle is compromised, either by injury or tightness, your running inevitably suffers.


If you find yourself shuffling more than usual, feeling a twitch in your stride, you might have a psoas injury. If you’re experiencing pain running uphill, walking up stairs, or doing any other activity that requires you to lift your knee, you might have a psoas injury. If you have hip, groin, or glute pain, you might have a psoas injury. If your lower back is aching … etc., etc…

The psoas is complicated.  Most runners don’t walk into their physician’s office and say, “Doc, my psoas is killing me,” because they don’t know about this muscle. They complain of other symptoms, from the lower back down to the foot.

Either way, it’s not enough to treat the psoas alone.  All issues of tightness, poor posture, weakness, and muscular imbalance need to be addressed together for successful resolution of a psoas injury.  Whether a strained psoas leads to low back pain or an achy back triggers an injury to the psoas, the symptoms should be treated in tandem.

If you can’t pin down which came first in the causal injury chain, the psoas is a great place to start. By treating the psoas, runners often find relief from pain in the low back, hip, hamstring, and groin.


Try this: Lie on your back with both legs straight. Pull one knee towards your chest. If the other leg lifts off the floor involuntarily, then your psoas is too tight. Now try the other side. Muscular imbalances are common, especially among runners, whose side-to-side discrepancies are reinforced through repetitive movement.

The number one culprit for a tight psoas is your chair.

Sitting for long periods puts the psoas in a continually shortened state.  Muscle memory maintains this shortened state, even when you head out for a run.

A short psoas can cause several postural problems: lordosis (arched lower back), anterior pelvic tilt (pelvis tipping forward), and hunching. Running with any of these postural dysfunctions can lead to a myriad of other injuries and issues, including hip, groin and lower back pain. Our bodies simply aren’t designed to sit all day.

But unless you’re in a financial position to quit your day job and become nomadic, you can’t avoid sitting in a chair. What can you do? Take a stand, early and often. Make it a habit to get up and stretch regularly. When you sit, pay attention to your posture. Don’t let your lower back arch. Sit up tall, like your momma told you, and don’t slouch.

Try and avoid excessive core work.  Doing too many sit-ups actually trains the psoas muscle to be short. And in running, you want the psoas to relax and extend. If it’s too taut, then the psoas can’t lengthen. Without that length, the psoas can’t contract with as much force. Six-pack abs should come with a warning label: Runners beware–too many sit-ups may cause psoas tightness.

Core is beneficial only in small doses. Too many crunches can wreak havoc on your psoas.


Whether you’re just recovering from a psoas injury or dealing with chronic tightness, start back slowly. Avoid any activity that aggravates the psoas, like hill running, until the pain subsides. If the psoas feels stiff or tender to the touch, enlist muscle release massage. Once the psoas is released and relaxed, the real work begins–undoing all those hours of sitting, at your job, in your car, at home. Regular stretching is the best at-home antidote to a tight psoas. (See the psoas stretches listed below.)

Remember, though, that your psoas didn’t get tight in one day, and the pain you experience is not going to get resolved in a day. You’re re-training the muscle, which takes time. So be patient and gentle. Overstretching the psoas can trigger a myotatic reflex, in which the muscle, instead of stretching, contracts and shortens. Ease into the stretch without straining, aiming for a lengthened sensation.

Lengthening your psoas not only decreases your risk of injury, but can also open up your stride. Picture the long sweeping stride of an Olympic runner. Now imagine your prototypical old man shuffler, skimming the sidewalk with each step. Whose psoas is shorter? More than likely, the shuffler’s. And whose is stronger? Without a doubt, the Olympic runner
Lengthening the psoas can open up your stride. It can cure a litany of injuries, improve your running posture, and lessen tightness and pain in the back, hip and groin. Sit less, stretch more and get ready for your running to improve.

Psoas Stretches


Sit tall at the end of a table, with your thighs halfway off . Pull one knee to your chest and lean back. Your lower back and sacrum should be flat on the table. If there’s any rounding in your back, or tipping of your pelvis, then you’re pulling the knee too far, so loosen your hold. The other leg should hang free off the table. Hold for 30 to 60 seconds for each side, and complete at least two or three repetitions.

NOTE: Physical therapists use this stretch as a flexibility test for the hip flexor. To pass, the posterior thigh should touch the table, and the knee should passively flex at an angle of at least 80 degrees.


Kneel on one knee, with the front leg forward at a 90-degree angle. With your pelvis tucked, lunge forward, easing into the stretch without straining. If your psoas is tight, your tendency may be to arch your lower back; make it a point to keep the back straight. Raise your arms overhead for an added abdominal stretch. To vigorously stretch the psoas, complete 20 reps on each side, holding the lunge for 2 to 3 seconds.


Step one foot 3 to 4 feet in front of you. Lunge forward until your front knee is at a right angle. (Readjust your foot position if necessary.) Turn your back foot out about 45 degrees. Keeping your back foot firmly planted, and your head, shoulders, hips and knees facing forward, raise your arms overhead. Relax your shoulders; don’t let them inch up. Lift your rib cage away from your pelvis to really stretch the psoas. As in all yoga poses, breathe deeply and easily. Don’t strain. Hold for 30 to 60 seconds.

More info about the psoas and more stretches:




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