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When you feel fearful, what sensations do you perceive in your body? Maybe you notice a lump in your throat, a shiver down your spine, or tensing in your jaw. But there’s another common response that you might not (consciously) notice: a tightening in the area of your hip ﬂexors. That’s your psoas major muscle—a sensitive tissue buried deep in your core. Your psoas helps you do things like hug your knees toward your torso, walk uphill, and climb stairs. In yoga, the psoas is important for stable, balanced alignment, proper joint rotation, and full range of motion. And when you feel threatened, it activates, preparing you to spring into action.
The Psoas Under Stress
The psoas plays a vital role in your stress response. When you experience a threat—perceived or real—your body has three main choices: fight, flight, or freeze.
In the ﬁght response, the psoas initiates dynamic defensive movements like kicking or punching; in ﬂight, it reﬂexively activates to help you run. Freezing may cause it to immediately contract so your body can assume a protective fetal position.
Evolutionarily, your psoas helped you bolt from predators, and it remains intricately linked to our fear response. That’s a good thing, because in the 21st century we still need to run from danger. The threat is just more likely to be an approaching bus than a saber-toothed tiger. Life pressures like an overbooked schedule or looming ﬁnancial problems can also cause your psoas to tighten and hold onto tension. Unfortunately, that contraction often persists long after the threat has passed.
Too much sitting—or even overdoing activities that are enjoyable and good for us, like running or biking—can cause this tissue to chronically clench. You might not feel this tightening in the psoas itself; the discomfort can show up as poor posture, back pain, and even increased anxiety.
Consciously practicing yoga postures that strengthen, stretch, and relax the psoas can liberate it from habitual holding patterns, improve your posture, and strengthen your ability to cope with and release fear and stress.
Your psoas is the only muscle to cross both the lumbar spine and the hip joint, acting as a muscular bridge between the trunk and lower extremities. It attaches at or below the last thoracic vertebrae (T12) and spans to the fourth lumbar vertebrae (L4). There, it crosses through the wing-like bone of the pelvis (ilium), then joins with the iliacus (which is why it is often called the iliopsoas muscle) before attaching to the lesser trochanter, the bony prominence on the femur near the pelvis.
This fan-like, spiraling muscle has three main functions:
1. Maintains posture: Humans are the only fully bipedal primates on Earth. Thanks in part to the natural inward curve of your lumbar spine—which helps absorb the shock of your movements—you can stand fully upright and walk long distances without support. Your psoas helps you maintain these vertical positions. You have a psoas on each side; these two pillars combine with the sacrum to create a strong triangular base to buttress up your core. Without this internal support, you would round your spine and hunch forward with bent knees.
2. Initiates movement: Your psoas is a hip ﬂexor, which means when it contracts, it pulls the thigh and spine close together. It starts the actions of walking, running, bending, and moving into many yoga poses, like lunges.
3. Responds to fear: Because of its location along the lumbar and sacral nerve plexuses, the psoas is highly innervated. That means it tends to be very responsive and explains why it’s one of the ﬁrst large skeletal muscles to respond when your nervous system perceives danger. The psoas is located near the diaphragm so each breath (deep or shallow) massages it. Deepening your breath can help relax your psoas, while shallow breaths may encourage the muscle to tense and tighten.
Strengthen and Stretch
High Lunges (see above) can dynamically awaken your psoas. In this pose, the front thigh contracts the muscle, strengthening it, while the back thigh stretches it. Lengthening the space between your legs deepens the stretch.
Like any muscle, your psoas becomes stronger when you challenge it. Move slowly in and out of the pose several times by straightening then re-bending your front leg. Then hold the shape for a few breaths longer than you want to.
To release your psoas, practice a version of Legs-Up-the-Wall, with your calves resting on the seat of a chair (or couch). This supine shape puts the muscles into a slack position, allowing space for them to deeply relax. Allow a slight curve in your lower back as you let all of your bones surrender to the force of gravity.
Invite in a sense of deep letting go in the front of your hip crease. After just one 5- to 20-minute session of practicing this shape, you will likely feel more relaxed in the area and experience some emotional ease.