The Psoas Muscle
The Psoas muscle (pronounced Soas) attaches to the anterior side of your Lumbar spine (lower back), deep within your abdominal region. It is one of only two muscles in your body that attaches your spine to your limbs, the other being your Latissimus Dorsi (‘Lats’) that attaches your spine to your upper arm. The Psoas traverses from your spine, deep through your abdominal cavity, until becoming quite superficial about your anterior hip (where it is joined by another deep hip flexor called your Iliacus – the two traveling together are then called your Iliopsoas). It then continues downward, again going deep, to attach to your femur (upper leg bone) deep within your groin region.
Because the Psoas traverses many joints (from your lower back to your upper femur) its actions are many. Predominantly however it is a powerful hip flexor (raises knee towards chest). It may also externally rotate the upper leg (turn leg out). Although debatable, the psoas may also cause the lower back to become lordotic (increased curve in Lumbar spine).
Runners would be aware that this muscle can be the cause of many running aches and pains. There are numerous symptoms that a runner may present with, that in way one or another leads back to an unhealthy Psoas. There is simply no way I could list all the injuries that this muscle may be involved with. To give you an idea however, this short list will help you on your way:
- The Psoas may become tight and immobile. This will limit your hip extension (when your leg trials behind you) and drag your lower back into lordosis (greater curve) putting you into a poor biomechanical running position and rendering you vulnerable to lower back pain and many other possible aches.
- When your hip stabilizers become fatigued (long run, excessive new training type/load) it is suggested that your psoas becomes over active in compensation. Again, this ends in a tight, immobile Psoas
- The Psoas may become weak. As a therapist this often is palpated as a thin, ropey Psoas with diminished size. As a runner, our fingers in your stomach may actually not cause that much pain. A weak Psoas often feels dead and achey in contrast to a healthy Psoas that usually feels full, bouncy and more acutely painful to palpate. Hence, don’t get fooled when your therapist digs into your ‘bad Psoas’ and it feels better than the apparent good side.
How does a Therapist assess for an unhealthy Psoas? There are length tests that can compare sides (called “Thomas tests’ or ‘modified Thomas Tests’), plus palpation techniques (feeling both sides to compare) as well as some strength tests. This is usually enough to figure out what state your Psoas is in and what should be done about it.
Home exercises for the Psoas is to keep it as mobile as you can. This is done by a hip flexor stretch with slight nuisances to isolate the Psoas. This stretch is difficult to isolate and many struggle to find it.
- Start by getting yourself into a kneeling position with one knee on the ground (the Psoas to be stretched) and the other leg out in front (foot on the ground, hip and knee at 90 degrees flexion)
- Now squeeze your gluteals. This will posteriorly rotate your pelvis (tilt it backwards) and increase the possible stretch on the Psoas
- Now gently lean backwards from your lower back – don’t move your pelvis, only your lower back. Again this will help isolate your Psoas
- Finally, slightly bring your foot (on the stretching Psoas side) ‘inwards’ towards your body. This will externally rotate your hip and once again increase the possible isolation of a Psoas stretch.
It is probably more advisable to do this stretch lightly and more often rather than aggressively and for long periods as the load on your lumbar spine may cause irritation to the joints in that region.
How do you know when your Psoas is weak? Get a health professional to test it for you. If deemed weak they can then suggest Psoas strengthening exercises for you.
Happy running.