PRI and the lower thoracic vertebrae



In June, I had the pleasure of taking Impingement and Instability, the final course in the Postural Restoration Institute’s catalog that has enough carryover to the training world to warrant the cost and time. I was hemming and hawing a bit leading up to it (16 hours of mostly lecture sandwiched between two heavy work weeks was causing a bit of consternation). Fortunately, I can genuinely say it is the best PRI course I have taken. It tied a lot of the concepts together, gave me some more ideas for how to utilize PRI beyond warm-up and cool-down, and made me aware of how important the reference centers used during the exercises really are. While James discussed six primary reference centers, I am going to focus on one- the thoracic vertebrae below T8.

One of the things PRI teaches is the importance of creating a zone of apposition (ZOA). The ZOA creates stability around the lumbar spine. If there is no ZOA at rest, it is virtually impossible (by PRI standards) to perform movement and exercise without relying on the more superficial stabilizing system. This doesn’t mean we never move out of ZOA; rather, the goal is to have ZOA as a point of return. In an active population (like clients that come in for personal training), this can be seen when individuals complain of jaw pain, neck tension, shoulder tension, mid back tension, hip tightness, and calf tightness during or directly after exercise. If you put someone on one leg and have that individual perform single leg, unweighted deadlifts, after the set when you ask where he experienced sensation, if the client says “my calves,” it is quite likely from a PRI perspective, the person lacks a ZOA. Different movement systems would have you address this different ways. I typically have the person perform a quick round of breathing, emphasizing position (more about this in a moment), inhibit the calf using some sort of down dog variation, and bring awareness to the feet before the next set to see if I can alter the person’s experience. 

The zone of apposition looks a bit like a canister, with the diaphragm acting as the top and the pelvic floor acting as the bottom. If the ribs flare up and out and the pelvis tips forward, the zone of apposition no longer looks like a zone; rather, it looks more like a sideways slinky. To be clear, other systems discuss the importance of rib cage position, and many movement professionals that haven’t studied PRI cue something that sounds a lot like “keep your ribs down,” so this isn’t a concept that is unique to solely PRI. PRI takes this idea of ZOA a step further by saying given our natural, asymmetrical way of being, it is more difficult to establish ZOA on the left side, which influences lots of things and can affect gait, and if you want to know more about that, you should take a course or chat with someone that has studied PRI.

Back to the anatomy that is the vertebral column. The diaphragm, which is the pinnacle of establishing ZOA, attaches to the lower six ribs, back of the sternum, and the upper 1-4 lumbar vertebrae (Chaitow,, 2013). It looks like 1/2 of a deflated balloon during exhalation and 1/2 of a filled balloon during inhalation. The diaphragm has a central tendon with fibers radiating out and attaching the lower portion of the thorax, forming the floor of the thoracic cavity. This also means the diaphragm’s ability to contract and relax dictates rib cage size and movement. If the diaphragm is impacted in some way, say, the ribs are always lifted up and away from the pelvis, the position of the lower thoracic vertebrae will be affected, as well as how the diaphragm contracts and relaxes. Put another way, what happens in the front of the body affects the back of the body. Like any muscle, resting length tension relationship is one the things that determines mobility. It is also worthwhile to note the diaphragm stabilizes the lumbar spine before movement by establishing abdominal pressure (Vostatek,, 2013). One could extrapolate from this if the diaphragm isn’t in a good position, lumbar spine stability might be compromised. This, of course, doesn’t really mean anything unless the stability isn’t there when you really need it. Interestingly, powerlifters often use a technique called the Valsalva maneuver, which essentially means maintaining intra-abdominal contraction with a breath holding strategy. To compensate for any potential lack of stability, they create as much stability as possible. If I were regularly picking up items three times my body weight off of the floor, I probably would too.

In addition to the diaphragm, there are several muscles that stabilize the lumbar spine. I am only going to talk about the abdominal muscles, though there are others. The muscles are layered on top of each other, with the external obliques existing as the outermost layer, followed by the rectus abdominis (or six pack muscle), the internal obliques, and the transverse abdominis. Both the internal obliques, and the transverse abdominis have attachment points at the lower 3 ribs, and lower six ribs, respectively (Kacmarek,). Again, if you look anatomically at what directly opposes the lower ribs, you will find T8-T12, an area in which many of us lack a mental connection.

So what does all of this mean? It is no surprise for people reading this that work in the movement field if you cue someone to direct his attention to the front of the body, this is fairly easy, and chance of success is high; however, if you move attention to the back of the body, things become a little more challenging, both for the practitioner and the student. The benefit of taking the time to learn how to access the lower thoracic vertebrae is the sometimes profound impact it can have on the ability to feel the abdominals and alter stabilization strategies. To accomplish this, I typically begin by directing the client’s attention to what is happening in the front of the body as we perform movements that bring the ribs into an expiratory position; once the client understands that sensation, I ask the client to pay attention to what is happening in the back of the body. When that has been clarified in a situation where the floor offers feedback, I move to positions where less tactile feedback will be given. Examples of a warm-up sequence I frequently use to bring awareness to this area can be found below.* I typically train thematically, with consistent cueing and attention to one area for the duration of the session, in each exercise. The warm-up I use reflects the area I want to highlight. 

To be clear, in discussing position and reference centers, it doesn’t mean we never move away from these places. This is a reference, a place to return to if the motion dictates extension or flexion. At the end of the day, the more clear the image of the physical body is in our heads, the easier and more fluidly we will move, regardless of what system or methodology is being used. T8-T12 is simply a starting point, and in my opinion, a pretty good one.

Yours in health and wellness,


Chaitow, L., Bradley, D., & Gilbert, C., (2002). Multidisciplinary Approaches to Breathing Pattern Disorders. Elsevier Science: United Kingdom.
Vostatek, P., Novak, D., Rychnovsky, T., & Rychnovska, S., (2013). Diaphragm postural function analysis using magnetic resonance imaging. PLOS One, 8(3).
Kacmarek, R.M., Stoller, J.K., & Heuer, A., (2014). Egan’s Fundamentals of Respiratory Care. Elsevier Science: United Kingdom.