Even though it's a major hip flexor, the Psoas can be a source of back pain for many people.
This muscle attaches at the lumbar spine, comes down inside the
Pelvic bowl, and inserts on the inner side of the femur. (see image)
When you sit too much, the Psoas gets short, and sometimes stays short.
When chronically shortened, it can keep you in a perpetually doubled over position. You may have seen people walk with a shortened jerky stride on one leg. Their hip (and leg) not able to extend back fully. The psoas is a likely culprit.
Once it gets tight, it can stay in the short position for a long time. Something has to be done to release it.
You have a few options:
1. Do Nothing (if it's not too bad), get used to the short stride, and let the rest of your body find ways to compensate (Not Recommended);
2. Get a massage to release the Psoas. (Highly Recommended)
This work is not very pleasant. It involves slow deep compressions into the muscle through the abdominal wall.
But when it's released, you may gain an inch in height and feel like you can take deeper breaths.
Not all massage therapists are trained in Psoas Release. Ask us who we would recommend for this type of work.
3. Strengthen it. (Also Highly Recommended)
Strong muscles stay relaxed, i.e. do not get chronically tight. Only weak muscles do that.
Ask a fitness specialist about how to strengthen the Psoas with exercise.
Strong healthy Psoas acts as a primary hip flexor without pulling on the back.
4. Stretch it. (Recommended Only for Non-Injured Muscles)
Stretching the Psoas on a regular basis will help you keep that fluid stride, and ease of movement.
However, if the muscle is injured, stretching it will make it worse. It's best to start with #2 and #3, and then add a stretching routine when it's strong and healthy.