So what is it about sitting that makes my back hurt so much? First and foremost, you’re not moving. The body likes to move, and you’ve locked it in one position. You’re driving to work, and pretty much your entire lower body is one static position the entire time. The body doesn’t like this and gives you feedback, i.e., pain, to let you know that it wants movement. Though we ignore the pain until it starts to affect our daily lives.
One of the primary muscles that contribute to this pain is the psoas(so-as). The psoas’ main action is to flex the hip; as in bringing the knee closer to the chest. However, it also has many secondary actions as well. The psoas also contributes to stabilizing the hip joint, the lumbar spine and helps when lifting heavier loads. Here is where the issue arises though. If the psoas becomes stiffened, there will be an increase of shear forces on the low back. There are a few ways that the psoas can become stiffened. Stiffening of the muscle can be due to injury, chronically shortened position due to not moving, or if it is overworked.
Through the work of McGill, a study revealed that a stiffened psoas muscle that becomes activated with activity would cause a shear force to the low back. Shear force is not dealt well from the lumbar spine and can be a source of pain if this is repetitively causing strain in this area. Most do not realize that their low back pain can come from the front of the body, so the psoas as a pain generator is often overlooked. The back is not the only place that the psoas can cause pain though. Another common area of pain resulting from the myofascial pain of the psoas is in front of the hip. The pain can feel like a pinch or dull ache. Irritated over time this muscle will start to cause a dull pain on the front of the thigh as well.
The picture above showcases this well as the “x’s” are common areas of irritation. Solid red patches are the places where the pain is felt, and the dotted area is where the pain will start to refer out when we don’t address the issue. Not only are people who sit for large portions of the day susceptible to injury in this area, but athletes are also as well. Some athletes can have an injury to the psoas, which includes those who dance or play hockey or soccer. These injuries are generally because the sport requires lots of hip flexion and it is the repetitive strain on the muscle that causes the pain.
Earlier it was mentioned that the psoas could assist with stabilizing the lumbar spine. Stabilizing is perfect for when we are lifting heavier loads. However, if our core is not doing its job to stabilize, the psoas now has to do more. The cores primary job is to stabilize the lumbar spine, and we can think of it as a cylinder. The top of the cylinder is your diaphragm, your primary breathing muscle. The bottom is the pelvic floor. The “sides” consist of your transversus abdominis(TA), external and internal obliques(EO/IO), and your rectus abdominis(RA). All these muscles play a crucial role and must work in harmony to properly stabilize the low back.
These are not the only reason that sitting can contribute to low back pain but it is a common one. In the follow-up blog, I will go through how to properly stretch your hip flexors and some exercises that can help train your core.
If you have any questions or would like more assistance on how to rid yourself of back pain, please do not hesitate to book an appointment with me, or send us an email for further clarification.
1. Sajko S, Stuber K. Psoas Major: a case report and review of its anatomy, biomechanics, and clinical implications. The Journal of the Canadian Chiropractic Association. 2009;53(4):311-318.
2. Santaguida P, McGill S. The psoas major muscle: A three-dimensional geometric study. Journal of Biomechanics. 1995;28(3):339-345.
3. Travell J, Simons D. Myofascial Pain and Dysfunction: The Trigger Point Manual: Volume 2: The Lower Extremities. Philadelphia: Lippincott Williams