Most yoga students are aware that the psoas is a central player in asana, even if the muscle’s deeper function and design seem a mystery. A primary connector between the torso and the leg, the psoas is also an important muscle off the mat: it affects posture, helps stabilize the spine, and, if it’s out of balance, can be a significant contributor to low back and pelvic pain. The way that we use the psoas in our yoga practice can either help keep it healthy, strong, and flexible, or, conversely, can perpetuate harmful imbalances.
The psoas major is the biggest and strongest player in a group of muscles called the hip flexors: together they contract to pull the thigh and the torso toward each other. The hip flexors can become short and tight if you spend most of your waking hours sitting, or if you repeatedly work them in activities like sit-ups, bicycling, and certain weight-training exercises.
A tight psoas can cause serious postural problems: when you stand up, it pulls the low back vertebrae forward and down toward the femur, often resulting in lordosis (overarching in the lumbar spine), which is a common cause of low back pain and stiffness; it can also contribute to arthritis in the lumbar facet joints. On the other hand, a weak and overstretched psoas can contribute to a common postural problem in which the pelvis is pushed forward of the chest and knees. This misalignment is characterized by tight hamstrings pulling down on the sitting bones, a vertical sacrum (instead of its usual gentle forward tilt), and a flattened lumbar spine. Without its normal curve, the low back is weakened and vulnerable to injury, especially at the intervertebral discs.
Although the psoas is one of the most important muscles in yoga poses, it is also one of the most misunderstood. Many students and even teachers have only a vague idea of where it is located. The psoas originates from the lumbar vertebrae and forms a strip of muscle almost as big as a wrist along each side of the spine. Looking at the front of the body, you’d have to remove the intestines and other digestive organs, as well as the female reproductive organs, to be able to see the muscle in the very back of the abdomen. It proceeds down and forward, crossing the outer edge of each pubis, then moves back again to attach on a bony prominence of the inner upper posterior femur (thigh bone) called the lesser trochanter.
Along the way, the psoas picks up its synergist, the iliacus, which originates on the inner bowl of the pelvis (or the ilium) and joins the psoas on its path downward to attach to the femur. The two muscles work so closely together that they’re usually referred to as one, the iliopsoas. The other hip flexors include the sartorius, the tensor fascia lata, the rectus femoris, the pectineus, and the adductor brevis. Besides flexion, these muscles might also contribute to the internal or external rotation of the hip. This action is important for yoga practitioners to understand because the psoas may try to externally rotate the hip in poses where we don’t want external rotation, such as backbends or forward bends.
A good way to isolate the psoas stretch, whether you’re a beginner or an experienced practitioner, is to practice virabhadrasana I in a doorway. Find an open doorway (or a pillar) and step up close so that the right side of your body is just behind the door jamb. Step your left leg through the doorway, and place your right foot two to three feet behind you, with that back heel off the floor. Stretch your arms overhead and rest your hands on the wall. Bend both knees slightly, and align your pubic bones, navel, and breastbone with the door frame.
The whole key to stretching the psoas is in the tilting of the pelvis. Remember, a tight psoas tries to tilt the pelvis anteriorly (pulling the spine and top of the pelvis forward and down), so you must tilt the pelvis posteriorly to stretch the hip flexors. The door can help you achieve this action: simply move your pubic bones toward the door jamb, your upper pelvis and navel back away from the jamb, and draw your breastbone toward the jamb. These actions help you tilt the pelvis posteriorly, move the lumbar spine toward the back of the body (instead of letting the tight psoas pull it forward and down), and lift the rib cage vertically up out of the low back. Altogether, you’ll be lengthening the psoas and relieving compression and discomfort in the low back.
When you’re ready to deepen the stretch, straighten the back knee fully (let the back heel stay off the floor, especially if you’re a beginner or have knee or low back problems), and gradually bend the front knee more. If you’re not getting a deep stretch on the front of the right hip, redouble your efforts to bring the pubic bones toward the wall, and the navel away, and bend the front knee more. Hold the pose for a minute or more, keeping your breathing slow and steady to help the muscle relax into a deep stretch. Then repeat on the other side.
A well-balanced asana practice helps keep your muscles strong enough to do their job and flexible enough to allow full range of motion of associated joints. By incorporating poses that both strengthen and lengthen the psoas, you can release habitual muscle-holding patterns, improve your low-back alignment, and create a more balanced and spacious posture.
Excerpts from Yoga International Article How to Stretch and Strengthen the Psoas: Want to find a new sense of balance and freedom in your practice? Learn how to skillfully stretch and strengthen the mysterious psoas muscle. By Julie Gudmestad