There are technically two parts of the psoas muscle, the psoas minor and the psoas major. The psoas minor is found in less than 50% of the population and is considered a vanishing muscle left over from our evolution into bipedal humans. The psoas major is the main part of the muscle and I will refer to it as the psoas from here on. The psoas is approximately 16 inches long and directly links the ribcage with the legs. It originates superiorly from the vertebral bodies and intervertebral disks of the twelfth thoracic to the fifth lumbar, and from the transverse processes of the lumbar vertebrae. The psoas then inserts inferiorly with the iliacus muscle by way of a common tendon to the lesser trochanter of the femur. These two important hip flexors are collectively known as the iliopsoas.
The psoas is located at the deepest core of our structure, where our ‘gut feelings’ reside. Sometimes our first instincts begin here. The psoas is strongly innervated since it inserts directly behind the diaphragm along the lumbar spine. At the L1 vertebrae, the psoas and diaphragm junction at the celiac (solar) plexus, directly linking psoas function to our breathing and digestion. This relationship illustrates that a constricted psoas can adversely affect one’s breathing and digestion. This area holds a lot of personal power and energy, so it is important to understand how interconnected our bodies are physically and emotionally. The lumbar plexus is also embedded in the surface of the psoas, which directly supplies energy to animate the legs and strongly influences both sexual and anal functions.
Starting from the lumbar spine and crossing over the hip joint, the psoas directly affects range of motion of the pelvis and the legs. The psoas has many functions, with the most direct and obvious being its role as a hip flexor. It supports the free swing of the legs while walking and is very important in transferring weight though the trunk to the legs and the feet. Sturdy and balanced walking should originate from the core and not from more superficial muscles. Through the action of walking, the psoas also acts as a hydraulic pump, stimulating and pushing fluids in and out of cells. The psoas plays a big role in posture by acting like a guide-wire that stabilizes the spine. Rectus abdominis counterbalances the tension of the psoas. When this relationship is out of balance it often leads to the ‘chest-out-belly-in’ posture. The psoas also has an intimate relationship with the internal abdominal organs by acting as the psoatic shelf. The psoas creates a support base along the bottom and back of the pelvis, upon which the abdominal organs rest. Therefore, tension in the psoas affects the space and function of the internal organs.
Constructive Rest Position
Once you become aware of the internal sensations and skeletal positions associated with releasing the psoas you can move on to more actively working the muscle. There are many positions to elongate and stretch the psoas, but the most important thing is appropriate body awareness so that the muscle is isolated while the rest of the body is relaxed. After releasing the psoas in the constructive rest position one can easily move into the active supine stretch. Continue lying in the constructive rest position. Begin by bringing your right thigh up toward the trunk of your body and gently hug your right knee. Be very aware to not move or tilt the pelvis while raising the right thigh and focus awareness to softening the hip joint. Now you are ready to stretch the left psoas. Slowly begin to extend the left leg out while keeping the pelvis still. The goal here is to isolate the movement of the leg from the pelvis. Focus your attention to the left hip socket and allow it to soften and release, feeling the psoas lengthen. Use no force and extend your left leg slowly into the stretch. Notice any sensations that you experience and STOP if anything is painful in the low back, and go back to the constructive rest position to help release the psoas again.
The active supine stretch is a gentle and easy way to begin working and elongating the psoas. Any variation of the lunge, or runners stretch, also focuses on stretching the psoas. Yoga also offers many great poses that work with lengthening the psoas, most notably pigeon pose (Eka Pada Rajakapotasana). For more information on specific stretches you can visit YogaJournal.com (http://www.yogajournal.com/practice/169) where Liz Koch has put together a nice summary on 10 poses beneficial for the psoas.
Releasing and stretching the psoas are both very important to the overall health of the body. By gaining better awareness of our bodies and being able to understand our bodily sensations we can start to change some of the negatively conditioned muscle patterns and practice proper body mechanics. To do this we must also strengthen our muscles. Before you begin to tone the psoas you must make sure that it is released. If the psoas is not released, your body will try to compensate incorporating the wrong muscle groups to perform the movement. To practice this next move for toning the psoas we will be using the same position as in the Active Supine Stretch (can also be done with the right leg planted at a 90 degree angle on the floor). Be sure to keep your pelvis stable so that the proper muscles are engaged. Once you are able to fully extend the left leg (or whichever side you are working on) you are ready to start toning the psoas and leg muscles. Begin by lifting the left leg about 6 inches up to the height of your hip socket. Slowly move the extended leg up, down, sideways left and right, and diagonally. Liz Koch says “When lifting your leg, think of the psoas muscle falling back along the spine and scooping the leg off of the floor.” This imagery will help isolate the appropriate muscle groups.