Facilitating Calm & Balance: Understanding the Multi-Functional Psoas Muscle

On the list of MVMs—most valuable muscles that is—the psoas muscle, or more precisely the iliopsoas chain, is at the top of any yogi’s list. It is after all, the physical link between the spine and the legs.

The primary muscular action of the psoas is spinal flexion and extension. It’s the predominant hip flexor, both femur-on-pelvis and pelvis-on-femur. It also plays a role in lateral flexion of the lumbar region and flexion of the low lumber spine relative to the sacrum. Importantly, the psoas also provides vertical stabilization of the lumbar spine while still accommodating the natural curves. It is part of the core.

Most yogis know that a weak, tight, or overstretched psoas can contribute to low back pain, dysfunctional movement patterns, and poor posture. But the psoas also has a role in the realm of physiology, breath and core support, and mood. For example, the psoas can play a role in pelvic pain, abdominal pain, irritable bowel syndrome, and anxiety.

Marlysa Sullivan, assistant professor at Maryland University of Integrative Health, teaches in the Yoga Therapy and Integrative Science departments. She maintains that a more comprehensive understanding of the various functions of the psoas can lead us to a more holistic approach toward working with it.

The Psoas Has Multiple Functions

As a physical therapist and yoga therapist, Marlysa has observed that it’s easy to misinterpret the cues we receive from the psoas. For example, we may mistake weakness or imbalance as tightness and the need to stretch. As a consequence, yogis often focus more on stretching and lengthening the psoas in poses such as lunges. We may actually need strengthening, rebalancing, or, in many cases, relaxing and releasing it instead.

To understand why, let’s first focus a bit on the anatomy.

Anatomy of the Iliopsoas

The psoas major attaches from the 12th thoracic vertebra and all of the lumbar vertebrae and intervertebral disks to the femur. The iliacus muscle attaches to the inner lip of the iliac crest and small region of the sacrum across the sacroiliac (SI) joint. Along the way, the psoas and iliacus fibers start to mingle and they share a ligamentous connection to the lesser trochanter of the femur. But the muscular links are only a partial picture.

By its position deep in the pelvic basin, the psoas performs a pump-like action that moves blood and lymphatic fluid throughout the cells. Marlysa points out that through the fascial connection between the psoas and visceral organs such as the kidneys and intestines, tightness in the psoas will also affect those organs.

“When the psoas is tight, the fascia that surrounds the organs will also be tight. It’s a bit of an indirect connection, but a tight psoas can limit organ mobility or motility and hinder the function of lymphatic flow and abdominal organs,” she explains.

Another important relationship is that between the psoas and diaphragm. By a fascial connection between the two, as well as proximity to the tendons that extend down from the diaphragm to the spine, the breathing and the psoas muscle share a close functional relationship. If one becomes tight or dysfunctional, the other is likely to be affected, so a chronically tight psoas can restrict the mobility of the diaphragm and restrict breath capacity.

The Psoas Connection to Fight-or-Flight

Marlysa points out that the diaphragm-psoas link also has great ramifications in mood control as well. When we are stressed or go into fight-or-flight mode, the psoas naturally contracts. It can also be the source of trigger points or a place to hold habitual tension. This is where an understanding of the link between the psoas and the autonomic nervous system—and how the psoas can play a part in our sense of equanimity and well-being—comes into sharper focus.

“Think about it,” Marlysa muses. “In a state of prolonged sympathetic overdrive or sympathetic activation—such as when we walk around in a perpetual state of low-level fight-or-flight or are dealing with trauma in our lives—we’re going to have more tone in the muscles that are used for fight, flight, or freeze. We’ll literally tense the big muscles like the psoas and the quadriceps that we use to run or to fight.”

A yoga pose that lengthens the psoas will do little to relieve this situation. What Marlysa advises instead to soothe the hyper-stimulated nervous system is to elicit the parasympathetic (rest-and-digest) response.

Relaxing vs. Stretching

“When I consider relaxing a muscle versus stretching it, the idea is that whenever you shorten a muscle, you bring the origin and the insertion closer together while creating a relaxed state. You’re not asking the muscle to do anything. So for example, when I’m sitting my psoas is in a shortened position. But I’m having to hold myself up so the psoas is working.”

A relaxed psoas facilitates a parasympathetic state throughout the body, because the body is able to move into relaxation mode. Via an indirect connection to the vagus nerve, Marlysa points out that releasing the psoas can also help take someone out of the dorsal vagal response that leads us to immobility or dissociation into this optimal parasympathetic state. This creates what Marlysa terms a bottom-up ventral-vagal response to the social engagement system.

Constructive Rest Pose

Marlysa’s go-to pose for psoas release and bringing about that relaxed state is Constructive Rest Position. Not technically a yoga pose, Mabel Todd first introduced Constructive Rest in 1937 in her groundbreaking book, The Thinking Body. It’s a position of complete rest in which the spine is relieved of the weight of the arms and legs, and the major joints are free to release into gravity and fall into rest. The goal is to distribute the weight of the body so that no work is required in order to maintain equilibrium.

“I joke with the students at Maryland University that everyone gets Constructive Rest because it’s the position that everyone needs,” laughs Marlysa. “And not to overstate it, but most people do really well if they do Constructive Rest. You combine five minutes of a totally relaxed physical state with longer exhalations and more relaxed breathing, then add in some meditation. It really facilitates the parasympathetic state. It’s a posture that people will do, especially when they realize how much it helps. A lot of my clients talk about how they use it for stress, anxiety, and back pain in particular.

“A trauma survivor can’t always use the mind to access relaxation, calm, peace and safety. But we can achieve it through the body. So what’s really just beautiful and magical about yoga is that we have techniques that can go from the mind (which is called top-down influence) or we can do practices that are based on the body (which is called bottom-up),” Marlysa states.

How to Practice Constructive Rest Position

1. Lie on your back and place your lower legs hips-width apart on a chair. If you like, place a yoga strap around your thighs to allow them to fully relax. Alternatively, you can also place your feet hips-width apart and allow your knees to rest on each other.
2. Find a comfortable resting position for your arms, either draping them across your body or on the floor with palms up.
3. Do not make any effort to “fix” your position or alter the curves of your spine. If your neck is overly flexed or your chin is higher than your nose, place a folded blanket under your head to relieve the imbalance.
4. Allow gravity to work its magic for 5-20 minutes.
5. Try using an eye pillow, restful music, or blanket over your body to enhance your experience.
6. When you are ready to come out of the position, bring your knees to your chest and slowly roll to one side, getting your bearings before pushing yourself back up.