The following is a guest post from Thomas Lucas from Physiomentum.
Could Your Hip Flexor Be Causing Your Low Back Pain?
The short answer is YES! To elaborate, when it comes to “pain” we need to consider that the human body is an amazingly complex system and the pain culprit can be far removed from the area that is actually hurting. We are going to take a look at fairly common, and often overlooked culprit of mechanical low back pain: the Psoas muscle.
To get comfortable with our topic we need to understand some basic anatomy.
There is a Psoas major as well as a psoas minor. We will only be considering the psoas major and we will simply refer to it as “psoas”.
The psoas muscle originates from the sides of the five lowest mobile segments of the lumbar spine (i.e. L1-L5). It travels downward, deep to the abdominal muscle group, and it crosses the hip joint where it finally attaches to the femur or “leg bone”. To make things complicated we also need to consider the iliacus muscle. This muscle originates on the front portion of the pelvis bone (very deep!). The iliacus then actually merges with the descending psoas to form what is called the iliopsoas. The iliopsoas is the anatomical term for what would be the infamous “hip flexor” muscle.
It’s also worth considering two other muscles that are also involved in the movement of hip flexion. (Hip flexion: the act of lifting your knee to your chest, or lifting your leg straight up while lying on your back) These are the Rectus femorus (part of the quadriceps muscle group) and the tensor fascia lata or TFL (closely related to the infamous ITband). Keep these in mind for later.
So when I explained how the psoas attaches directly to your spine, bells should have started going off in your head: there is a good chance that this structure could cause pain in a general area that it attaches to. There are actually a few theories that explain how this muscle can cause low back pain:
Referred Pain from Trigger Points
A trigger point is a specific area in the muscle that can become “active”. When a trigger pt. is active it sends pain signals to the brain. The brain interprets and localizes these signals, sometimes the brain does a good job and accurately localizes the pain over the structure that has the trigger pt. but quite often the brain wont be so accurate and you’ll feel pain, say in your upper arm, even though the muscle with the active trigger pt. is located in your upper back. To give a clinical example of this particular situation, if you have an active trigger pt. in your iliopsoas, applying pressure to this trigger pt. would reproduce pain in your low back (nowhere near where the pressure is being applied).
Distorted alignment and Compression
I consider this to be the more classic theory of low back pain caused by hip
flexor tightness. If we consider the line of pull of the iliacus muscle, as well as the Rectus femoris and TFL (remember these!?), we can appreciate that if they were very tight then they would, in a way, be “pulling” the pelvis into what’s called an “anterior pelvic tilt). With the pelvis tilted anteriorly, the lordosis (curve of the spine) is accentuated which can cause compression in the facet joints of the spine. If these joints experience more compression then they’re used to for a sustained period of time, they will become irritated and painful. In a similar train of thought, if we consider the line of pull of the psoas muscle, we can imagine that if it was excessively tight it could have a sandwich-like effect on the intervertebral discs of the low back. This sustained pressure on the discs can also result in pain signals being sent to the brain.
The truth of the matter is, it hasn’t really been proven that tight hip flexors even distort the bodies posture, and therefore couldn’t possibly be causing all this joint compression and associated pain. Take that with a grain of salt, because there is a difference between an idea that has not been proven, and one that has been disproved. Interestingly however, there has been a lot of research done of chronic low back pain. Some of these studies have discovered that the iliopsoas is one of the muscles that atrophy’s (i.e. becomes weak) in cases of chronic low back pain. This suggests that the iliopsoas may have a critical role to play in the functioning of a healthy low back. In other words, your hip flexor is actually a key stabilizer of the lumbar spine. While the cohort of chronic low back pain (i.e. pain for greater than 3 months) that has been studied may not represent this particular audience, it wouldn’t be a stretch to imagine that the iliopsoas also played some role in the acute stage of these low back pain cases. In fact, clinically what we (physiotherapists) tend to find is that people with low back pain (acute or chronic) often have poor muscular control and weakness of the iliopsoas. When a muscle is weak, or cannot handle the demands being put on it, it will often go into spasm, tighten up, and can even develop active trigger points. In these cases we will apply myofascial (muscle) release techniques to “loosen” up the muscle. Very often the person will have less pain afterwards, and demonstrate improved control of the iliopsoas. While our muscle release techniques likely help the muscle relax, they probably also act to “wake-up” the muscle and stimulate it to do its job a little better. Keep that in mind the next time someone is “releasing” your muscle.
My humble opinion
So after all this, perhaps it’s not the tight iliopsoas that alters the alignment of the spine causing distortion and compression of our joints. Based on the little bit of research that has touched upon this topic, it seems more likely the weakness and poor motor control of the iliopsoas would result in instability between some of the vertebrae in the lumbar spine. This instability (i.e. abnormally excessive movement of bone on another bone) can cause mechanical irritation, potentially inflammation, and subsequent pain. The iliopsoas, weak and overused, may even refer pain into the area of the low back (Trigger points!). Keep in mind that there are certainly other ways for a “tight” iliopsoas to develop, such as prolonged sitting, and other repetitive movements involving hip flexion.
Hip Flexor Fix
While I recommend a visit to your physiotherapist to determine the cause of your low back pain, you can try this in the meantime if you have a hunch that your iliopsoas may be a part of your back troubles. Before your work out, release your own iliopsoas (see my video). As well as performing your normal workout, I would recommend integrating some combined core/hip flexor exercises (e.g. the “Jackknife”) to build up some strength and control of the hip flexor. The idea is that you will be stimulating it to function better, and do it’s job which in this case is to stabilize your low back!
About the author
Tom is a Physiotherapists and member of the “Ordre Professionnel de la Physiotherapie du Québec”. He graduated from McGill University in 2011 with a Master’s Degree in Physiotherapy. He has spent his life in and around sports, most notably soccer where he won two National Championships as team captain for the Lac-St-Louis Lakers. More recently, he spent 5 years as captain of the McGill Redmen Varsity soccer team. He uses his experiences as an elite athlete to better help his injured athletes return to play in the best possible state. On a professional side he is currently pursuing his Manipulative Therapy levels, as well as his Certificate in Sports Physiotherapy. As an evidence-based practitioner, he hopes to one day contribute significant research to the profession of Physiotherapy.
Today Tom is owner and vice-president of his own company: Physiomentum Sports Medicine Centre Inc. through which he has participated in the coverage of many sporting events such as the 2013 Francophone Games with the Canadian Soccer Association, as well as the Cheerleading World Championships in Orlando.
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