Lower Back & Hip
Quick Reference
The iliopsoas is technically two muscles — the iliacus and the psoas major — that share a common tendon and insertion point on the lesser trochanter of the femur. Together, they form the primary hip flexor. The psoas also attaches to the lumbar vertebrae (T12 through L5), making it the only muscle that directly connects the lumbar spine to the lower extremity. This is what makes it so clinically significant: when it's tight, it doesn't just affect hip mobility — it directly loads the lumbar spine.
The iliopsoas is held in a shortened position whenever the hip is flexed — which is to say, whenever you're sitting. If you spend several hours per day sitting, the muscle adapts to that shortened length. Over time, it loses the ability to fully lengthen. When you stand up, tight hip flexors pull the pelvis into anterior tilt (forward rotation), which increases the lumbar curve and compresses the posterior structures of the lower back — facet joints, intervertebral discs, and supporting ligaments.
The result is that dull, achy lower back pain that gets worse after sitting for a long time, improves briefly when you first stand, and then aches again after walking or standing for a while. Many people blame weak abs or a disc problem when the primary driver is adaptive shortening of the hip flexor complex.
The iliopsoas doesn't just cause local hip flexor tension. The psoas major, when it contains active trigger points, can refer pain to the lower back, the groin, and even the anterior thigh. This referred pain pattern is commonly misidentified as disc pathology or hip joint problems. A thorough soft-tissue assessment will include palpation and testing of the iliopsoas in any lower back pain presentation.
Sustained hip flexor stretching — particularly the 90/90 lunge position held for 2–3 minutes per side — is the highest-return self-care intervention. The emphasis on duration is important: connective tissue and muscle don't respond meaningfully to 15-second stretches. Two to three minutes of sustained load is where you start to see actual tissue length changes.
Direct manual therapy to the iliopsoas — trigger point release and myofascial work — can significantly accelerate the process. The psoas is accessible through the abdomen with careful technique, and the iliacus is reachable just inside the iliac crest. This is work done regularly in Boulder massage therapy sessions for clients with chronic lower back and hip pain.
Pairing hip flexor lengthening with glute strengthening is important. Tight hip flexors and inhibited glutes are almost always found together — they're two sides of the same compensation pattern.
Have questions about this in your own body?
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