Psoas and Yoga: Hip Flexor Anatomy and the Poses That Help

The psoas (said "SO-as") is a deep hip flexor that runs from the sides of your lower spine, through the pelvis, to the inside of the upper thigh bone. Together with the iliacus it forms the iliopsoas, the strongest muscle for lifting the thigh toward the trunk. In yoga you stretch it in poses that take the hip behind you, like a low lunge, and you work it in poses that lift the legs, like Boat Pose.

What is the psoas?

The name comes from the Greek psoa, the loin muscles. Anatomy books describe two muscles with this name, plus one close partner:

• Psoas major. The big one. It starts on the sides of the vertebrae from the last thoracic vertebra (T12) down through the lumbar spine, and on the discs between them.
• Psoas minor. A thin muscle in front of the psoas major. Many people do not have one; studies put the share without it at somewhere around 40 to 50 percent.
• Iliacus. A fan-shaped muscle that lines the inside of the pelvic bowl. It is a separate muscle, not part of the psoas.

The psoas major and the iliacus meet in the groin, pass under the inguinal ligament and attach with a shared tendon to the lesser trochanter, a small knob on the inner back of the thigh bone. That shared unit is the iliopsoas. It is the only muscle that runs from the lumbar spine to the leg.

The psoas lies deep. That is why you rarely feel it on its own. What you feel in a lunge is the whole front of the hip.

What the psoas does

• Flexes the hip. It lifts the knee toward the chest, or tips the trunk toward the thighs when the legs are fixed, as in a sit-up. This is its main job, and the old idea that it "has little to do with the hips" is wrong.
• Holds the lumbar spine. When it contracts, it presses the lumbar vertebrae together along their length. Researchers still discuss how much it bends or straightens the lower back; most agree the effect is small compared with its pull on the hip.
• Works when you walk. It swings the leg forward at every step, and it works hard when you run uphill, sprint or kick.

The upper end of the psoas passes under the medial arcuate ligament, one of the arches the diaphragm anchors to. So the two sit close and share connective tissue. That is a real anatomical link. It is thinner than the phrase "the psoas connects to the diaphragm" makes it sound.

What a "tight psoas" means

When yoga teachers say "tight psoas", they usually mean the hip will not extend far: the thigh stops before it can travel behind you. A physiotherapist checks this with the Thomas test. You lie on your back at the edge of a table, hug one knee in and see whether the other thigh stays down.

Long hours of sitting keep the hip bent, and many people feel stiff at the front of the hip after a day at a desk or a long drive. How much sitting shortens the muscle itself is less clear. Some people with the feeling of a tight psoas turn out to have a weak one, or tissue that is sensitive rather than short. The practical answer covers both: stretch it, and make it work.

A sore groin, pain deep in the lower belly or pain at the front of the hip that clicks, catches or gets worse with every class is a reason to see a physiotherapist or doctor. Hip joint problems and hernias can feel like a tight hip flexor.

Yoga poses that stretch the psoas

A stretch for the psoas takes the hip into extension: the thigh goes back behind the line of the body. Keep the pelvis level and the lower back long, or the lumbar spine arches and takes the stretch away from the hip.

Low Lunge (Anjaneyasana)

1. From Downward-Facing Dog, step your right foot forward between your hands.
2. Lower the left knee to the mat. Put a folded blanket under it if the knee is sensitive.
3. Stack the front knee over the ankle. Lift your chest and rest your hands on the front thigh or on blocks.
4. Draw the front of your pelvis up toward your lower ribs, a small tuck of the tailbone. You feel the front of the left hip light up before you have moved forward at all.
5. On an exhale, let the pelvis move forward a few centimetres. Stay for 5-10 breaths, then change sides.

Our step-by-step guide to Anjaneyasana (Low Lunge) covers the arm variations and the knee options.

Bridge Pose (Setu Bandha Sarvangasana)

1. Lie on your back, knees bent, feet flat and hip-width apart, heels a hand's length from your sitting bones.
2. Arms long by your sides, palms down.
3. Press into your feet and lift the hips. Let the glutes and the backs of the thighs do the lifting.
4. Stay for 5 breaths, lower slowly and repeat two or three times.

The glutes extend the hip while the front of the hip lengthens: a milder psoas stretch than the lunge, with strength built in. More detail in Setu Bandha Sarvangasana (Bridge Pose).

Half Frog on the belly

1. Lie on your belly and come up onto your forearms, elbows under the shoulders.
2. Bend your right knee and reach back with your right hand for the foot. Use a strap around the foot if you cannot reach.
3. Press the pubic bone into the mat and draw the heel gently toward the hip. Stay for 5-8 breaths, then change sides.

This one stretches the quadriceps as well, including the rectus femoris, the other big hip flexor that crosses the front of the hip. If the knee complains, keep the heel further from the hip.

Deeper backbends

Once the lunge is comfortable, Virabhadrasana I (Warrior I) stretches the back leg's hip flexors while you stand, and Ustrasana (Camel Pose) and Dhanurasana (Bow Pose) ask for hip extension on both sides at once. In each of them, lengthen the front of the hips before you bend back, not after.

Yoga poses that strengthen the psoas

A strong psoas is as useful as a long one.

Modified Boat Pose (Navasana)

1. Sit with your knees bent and feet on the floor. Hold the backs of your thighs.
2. Lean back until you are balanced a little behind your sitting bones, with a long spine and relaxed shoulders.
3. Lift one foot, then the other, until the shins are parallel to the floor.
4. Keep breathing into the sides of the ribs. Stay for 3-5 breaths, lower, and repeat.

The psoas holds the trunk up against gravity while the abdominal wall stops the lower back from arching. The full pose is in Paripurna Navasana (Boat Pose), and our guide to core and yoga shows how it fits with the rest of the trunk.

Reverse Plank (Purvottanasana)

1. Sit with your legs forward and your hands on the floor behind you, fingers pointing toward your feet.
2. Start with knees bent and feet flat. Press into hands and feet and lift the hips to a tabletop.
3. For the full pose, straighten the legs one at a time and press the soles toward the floor.
4. Stay for 3-5 breaths.

The old version of this article called the reverse plank a psoas strengthener. It is the other way round: the glutes and hamstrings hold the hips up, and the front of the hips stretches. It belongs with the stretches, and it builds strength in the back of the body and the arms.

Standing knee lifts

Stand in Tadasana (Mountain Pose), lift one knee to hip height and hold it there for 5 breaths without leaning back. Then lower slowly. Five on each side is a short, honest hip flexor workout. Short strength drills like this fill our 15-minute Hip Flexors Time class.

Who should go carefully

• Recent groin or hip flexor strain. Stretching a fresh strain can make it worse. Rest it, and let a physiotherapist decide when to load it again. Pain in the groin that stops you from lifting the leg at all needs a doctor.
• Pregnancy. Lunges and Bridge are usually fine. Skip the belly-down stretch and Boat Pose from the second trimester, and follow your midwife's advice.
• Lower back pain. If backbends pinch in the lumbar spine, stay with the low lunge and Bridge, keep the tuck of the pelvis and move less far.
• Hip replacement. Some surgeons limit hip extension or rotation for a period after surgery. Ask before you lunge deep.

Common mistakes

• Arching instead of stretching. In a lunge the lower back arches and the pelvis tips forward. The stretch vanishes from the hip. Draw the front of the pelvis up first.
• Chasing depth. Sliding the back knee far away feels bigger but often stretches less. A modest lunge with a level pelvis does more.
• Holding the breath in Boat. The belly goes rigid and the breath stops. Bend the knees more and keep breathing.
• Only stretching. A hip that feels tight may need strength as much as length. Mix both in the same practice.

Yin Yoga and the psoas

Yin Yoga holds passive poses for three to five minutes, sometimes longer. For the front of the hips that means poses like Dragon (a supported low lunge), Saddle (a reclined kneeling backbend) and Sphinx. Yin teachers say the long holds work on the connective tissue more than the muscle. That theory comes from Paul Grilley and Sarah Powers and is not settled science. What you can count on: a long, quiet hold gives the muscles time to stop guarding, and many people find they can go further at the end than at the start.

The 45-minute Yin Yoga for the Psoas class is built on these long holds, with a bolster and a block.

Constructive rest

Lie on your back with your knees bent and feet flat, hip-width apart. Let the knees lean in against each other so the legs need no effort to stay up. Rest your hands on your belly. Stay for 10-20 minutes.

The position comes from Mabel Todd and Lulu Sweigard, who taught posture through imagery in the first half of the 1900s, and psoas teachers such as Liz Koch made it popular again. The hip flexors have nothing to hold, so they can soften. It is a kind place to end a hip session, before Savasana (Corpse Pose).

Where the sources disagree

"The muscle of the soul." You will read that the psoas stores fear and trauma, that a tight psoas keeps you in fight-or-flight, and that releasing it frees old emotions. The phrase is mostly credited to Liz Koch's books on the psoas, and sometimes to Ida Rolf, the founder of Rolfing. Stress does raise muscle tension around the body, and slow, supported poses can help you relax. No study shows that the psoas holds emotions in a way other muscles do not. The old version of this article also claimed a tight psoas drains the adrenal glands and wears down your health. Adrenal fatigue is not a recognised diagnosis, and we have removed those claims.

The psoas and the diaphragm. They meet through connective tissue at the top of the psoas, and both work when you breathe hard and move hard. That a relaxed psoas relaxes the breath, or the other way round, is a teaching image. It may help on the mat. It is not a measured effect.

Sitting and tightness. Many teachers say sitting shortens the psoas. The research on whether sitting shortens hip flexors over time is thin, and results differ. Stiffness after sitting is real. Moving the hip through its full range, and taking breaks from the chair, is sound advice either way.

Back pain. A tight psoas is often blamed for lower back pain. Some people with back pain do have limited hip extension, and some do not. Hip flexor stretches can help in a broader programme. They are not a fix on their own.

For a full class on the front of the hips, the 25-minute Low Lunge Class works through lunges step by step. Runners can go on with yoga for runners and why the hips lock.

Frequently asked questions

How do you release the psoas muscle in yoga?

Take the hip into extension, slowly. A low lunge with the back knee down and the pelvis drawn up is the main stretch. Bridge Pose is a gentler one. Hold for 5-10 breaths, breathe out as you ease forward, and end lying in constructive rest with the knees bent.

How do you release a tight psoas?

Combine stretching with strength. Low lunges and Bridge lengthen the front of the hip, standing knee lifts and a modified Boat make the psoas work, and fewer long stretches in the chair help more than any single pose. If the tightness comes with sharp groin pain, see a physiotherapist.

What are the symptoms of a tight psoas?

The common signs are stiffness at the front of the hip after sitting, a short stride when you walk or run, and a lower back that arches in lunges because the hip will not extend. These signs are not specific to the psoas. The rectus femoris and hip joint problems can give the same picture.

How do I know if my psoas is released?

You cannot feel the psoas on its own, so look at what the hip can do. In a low lunge the pelvis moves forward without the lower back arching, and in the Thomas test the thigh rests flat. You may also notice a longer stride and less stiffness when you stand up.

Is the psoas a hip flexor?

Yes. Together with the iliacus it forms the iliopsoas, the strongest hip flexor. It lifts the thigh toward the trunk, or the trunk toward the thighs. It also presses the lumbar vertebrae together, which helps hold the lower spine.

Why is the psoas called the muscle of the soul?

The phrase comes from somatic and yoga teachers, mostly Liz Koch, who see the psoas as a place where the body holds fear and stress. It is an image from teaching, not a finding from anatomy. The psoas reacts to stress like other muscles do.

Is yoga good for the psoas?

Yoga has both halves of what the psoas needs: poses that take the hip into extension, like lunges and backbends, and poses that make the hip flexors hold a load, like Boat. A practice that includes both keeps the front of the hip long and strong.