What does iliopsoas have to do with back pain?
There are many possible conditions that can lead to back pain. Iliopsoas issues are a potential contributing factor that can often be overlooked. In this article, we’ll explore some common ways in which the iliopsoas can contribute to back pain.
Before we dig in further to examine the function of the iliopsoas, let’s be clear about what kind of back pain we’re talking about. The term “back pain” is very non-specific. Even “the back” can be a broadly defined area depending on who you are asking. So, if we’re talking about back pain that might have a relationship to iliopsoas, we are most likely talking about pain or discomfort felt in the low or mid-back. Anatomically, we’re looking at the sacral area, lumbar area, and the lower portion of the thoracic area.
Where is the iliopsoas?
The iliopsoas takes a path from the twelfth thoracic vertebrae along the lumbar spine, across the joint connecting the lumbar spine to the sacrum, across the sacroiliac joint, and across the hip joint to attach onto the lesser trochanter. Because iliopsoas takes such a long path through the center of the body, it can affect what we feel through the front, the back, and the sides of the body in this area.
Of course, no muscle works alone. As you might remember from our articles What is a Muscle? and What is Muscle Fascia?, everything in the body is intricately interconnected. This necessary interconnection and balance is maintained by tissues in the body. When something is out of balance, we might experience pain or discomfort.
Imbalance within the iliopsoas muscle
The path of iliopsoas is long, so an imbalance in tension between the top and bottom of this muscle can create feelings of shortness, discomfort, or pain in the low back or sacral area. If the upper part of iliopsoas (area from approximately T12 to L2) has excess tension, then that area of the spine would be pulled down and forward. It could be experienced as feeling locally short and tight, or it could refer pain elsewhere. Likewise, if the lower part of the iliopsoas (area from approximately L2 to L5) has excess tension, then that area of the spine would be pulled down and forward. As with tension in the upper part of the muscle, tension in the lower part could be experienced as shortness or tightness in the low back or sacrum and could refer pain.
In general, the contribution of any part of iliopsoas to creating an excess anterior tilt of the pelvis has the potential to compress the lower back.
Why might an imbalance occur between the top and bottom of iliopsoas?
Everyday activities, such as sitting, can lead to chronic contraction of the iliopsoas. It’s common for us to sit a lot. We might sit for most of the day, at a desk, in a car, on the couch, etc. As the iliopsoas is the primary muscle that brings the thighs towards the torso or the torso towards the legs, we contract this muscle most of the day if we are sitting.
Other contributors to imbalances of tension within the iliopsoas muscle are sports and other athletic activities, such as running and cycling. There can also be anatomical or bony differences between sides of the pelvis or conditions, such as scoliosis, that lead to shortened areas of the iliopsoas.
Imbalance between iliopsoas and other muscles
In addition to an imbalance within the muscle, there can also be an imbalance between the iliopsoas and key muscles that work with it to stabilize the pelvis. Iliopsoas has an important relationship with several other muscles. It is the relationship of tension between iliopsoas and other muscles that creates balance around the pelvis and allows for ease and efficiency in movement. If any one of these relationships is out of balance, we might experience sensation, discomfort, or pain from it.
In particular, let’s take a look at the relationship between iliopsoas and piriformis and iliopsoas and the gluteal muscles. It’s important to note that iliopsoas can be out of balance with the piriformis and/or the gluteal muscles on just one side of the pelvis or both sides. This can create different postural changes and pain patterns.
Balancing the iliopsoas and piriformis
Let’s take a look specifically at the relationship between iliopsoas and the piriformis muscle.
These two muscles work to maintain a balance of tension around the sacroiliac joint (SI joint). Piriformis works to pull the bottom of the sacrum and the coccyx (tailbone) towards the pubic bone. Because the path of iliopsoas takes it from the spine over the pubic bone on the way down towards the top of the femur, it puts some tension on the SI joint via the vertebrae above. This then creates the opposite action of piriformis and pulls the coccyx and bottom of the sacrum away from the pubic bone.
If there is too much tension in either of these muscles, then there is potential for the SI joint to get pulled too far in either direction around its axis of rotation. Too much force from any direction that is going into the SI joint can cause discomfort and pain.
Balancing the iliopsoas and the gluteal muscles
Iliopsoas is a hip flexor and gluteus maximus is a powerful hip extensor. They work together to help maintain a balance of tension around the pelvis. If a short, contracted iliopsoas overpowers a weaker gluteus maximus on one or both sides of the pelvis, this can result in a shortened area of the low back, and potentially pain.
Iliopsoas also functions to externally rotate the hip, as do gluteus minimus and gluteus medius. Strong, short, lateral gluteal muscles can exacerbate the actions of an out of balance iliopsoas and direct force into the SI joint, again, potentially creating pain.
Trigger points and back pain
Trigger points in the iliopsoas muscle are also a potential cause of discomfort and pain in the low back. Exactly what causes trigger points is still being explored by researchers, but a current hypothesis is that trigger points are points in the body where a small number of muscle cells are stuck in a state of contraction. Those points then refer sensations, including possibly pain, to other areas in the body. In the image below you can see the X's marking common trigger points in the iliopsoas muscle and common referral pain patterns.
While the iliopsoas is one potential contributing factor to back pain, remember that sourcing back pain is complicated. If you’re experiencing back pain, make an appointment with a medical professional who can do a thorough assessment and look at the whole picture. If you’d like to learn more about the iliopsoas, you can read our article series on the iliopsoas, including How to Contact Your Iliopsoas, and Iliopsoas and Movement.