Does anybody know what Lower-Crossed Syndrome is?

When I was growing up, nobody in my immediate family had much of a medical background. So when I got into athletic training, everything was new and foreign to me as I was learning about the human body. One of the greatest lessons I've learned about the body is how little we actually know! I think this article discussing lower-crossed syndrome (LCS) is a good example of that. Or maybe I just still have a lot to learn, but either way I'd like to start this discussion.

Let me start by saying, I know what lower-crossed syndrome is. Well I know what the concept is and I know how the textbook describes it. My confusion lies in the pathology and reasoning for LCS. The textbook definition of LCS goes something like this "Tightness of the thoracolumbar extensors on the dorsal side crosses with tightness of the iliopsoas and rectus femoris. Weakness of the deep abdominal muscles ventrally crosses with weakness of the gluteus maximus and medius." See the image below for clarification, but basically we are talking about tight low back/hip flexors along with weak abs and glutes. We will use this as our common understanding of LCS when comparing these other ideologies. I want to preface the rest of this article by stating I am no expert with these systems, but this is simply my understanding of their philosophies.

Almost a year ago, I took a level one Reflexive Performance Reset (RPR) course. The course is very loosely modeled after Douglas Heel's Be Activated courses if anybody is more familiar with his work. Essentially, RPR is designed/presented as a warm up routine that targets specific "trigger points" which increase neuromuscular signaling to corresponding muscle groups. That's about as much depth as the course offers to the level one participants. On my own, I did a lot of research into the "neurolymphatic" system and put together my own theories/usage of RPR techniques in the rehab setting but I'll save all that for another article. RPR also incorporates a large element of diaphragmatic breathing. With their breathing techniques, you will see a change in certain passive motions. The breathing is a big connection from RPR to LCS. The iliopsoas muscle is deeply connected to the diaphragm through some of the thoracolumbar fascia. If we don't use the diaphragm properly to breath and it becomes restricted, so will the iliopsoas (hip flexor) through its fascial connection; giving the sensation of being "tight". Reciprocal inhibition dictates that if the hip flexors are tight/restricted, the glutes will not properly function. Then the athlete will compensate around the glutes with the lower back and hamstrings. Tight hip flexors, glutes that won't fire, and compensating (tight) lower back will tilt the pelvis and put the abs in a poor position to work. So there is the neuromuscular cascade that leads to LCS according to RPR. According to them, limits with diaphragmatic breathing also limit the iliopsoas and so on.

A couple months ago I took a Postural Restoration Institution (PRI) course, specifically their primary course titled "Myokinematic Restoration". This course is centered around the mechanics of the pelvis and the muscles that control it. One of the big lessons taught by the institute is the fact that the human body is asymmetrical. This opens the door for the next thought; because of asymmetries in our design, humans are naturally predisposed to specific postural patterns. Without going into extreme depth with their approach (their courses are incredibly detailed), these postural patterns could create the environment of LCS. For an athlete with bilaterally forward tilted iliums, their glutes become "dormant" because they have no positional power. The psoas muscles have to now work as external rotators in this position (which would make them feel "tight" for the athlete). Sagittal plane muscles now work in the transverse plane to balance out the athlete. The abs would have to become "dormant" or the athlete would fall forward. Lats and thoracolumbar extensors work as rotators as well. Slightly different terminology, but this pattern is effectively the same clinical presentation as the common understanding of LCS.

So, who is "correct"? I think the most common answer to that would be something along the lines of "every case is different". Which I agree with, but depending on your understanding of LCS and the pathology you choose to align with, your interventions may differ. I'm sure there are other interpretations of LCS and methods to identify and address it. As I stated before, I don't claim to be an expert on either PRI or RPR, or LCS for that matter. But I thought this would be interesting context to discuss the influence of opinions and philosophies on a subject that we truly don't know as much as we think; the human body.


Sincerely,
-Mark D.

@MarkDomATC