Do You Have a Zone of Apposition?

A primary goal of Postural Restoration® is to achieve and maintain a solid Zone of Apposition while achieving tri-planar movement.

In plain English, this means that your body can move in all three planes of motion: sagittal (front to back), frontal (side to side), and transverse (rotation), while keeping your rib cage positioned correctly.

Examine the pictures below. There are two big differences between me and my two clients. Visually, you’ll see my left hip is completely off the bench. Theirs are not.

Pelvic strength and the ability to establish and maintain a left Zone of Apposition during dynamic movement, is the difference.

You can stop the slide show on any particular picture by positioning your cursor on the picture.

  • Hruska Adduction Lift Test
    Gina can lift her left knee, but she can't get her bottom hip off the bench. She hasn't yet developed strength in her pelvis and internal obliques.

The Zone of Apposition

The zone of apposition is the area from the inside  of the bottom ribs, where the diaphragm attaches, to the top of the diaphragm. If the ZOA is present, the diaphragms will be nicely dome shaped and enable proper diaphragmatic breathing. The following pictures show what a ZOA is, an optimal ZOA, and a suboptimal ZOA. Placing your cursor on any of the pictures will stop if from changing to the next one.

  • this is an image of a zone of apposition
    ZOA = vertical distance between rib attachment of diaphragm and the top of its dome.

The first picture shows the ZOA. Notice it is referring to the vertical area that starts at the bottom of the ribs and extends up to the top of the dome of the diaphragm. In it’s natural state it should be domed, like in this picture.

The next picture shows an optimal ZOA. You will notice the domed shaped diaphragm. If you can attain this ZOA, it means your lower back will be in a truly neutral position, your abdominal muscles truly engaged, and your diaphragms truly working. I say truly because most people believe they are maintaining a neutral spine, believe they are engaging their abdominals, and believe they are diaphramatically breathing, but they are not because their biomechanics dictate that this can’t be the case. Unfortunately, the vast majority of us will look like the next picture.

In the third picture the diaphragm has lost its nice dome shape. It has become much flatter. This is because the ribs are raised in front (and almost always have a left pelvis rotated forward) . When the ribs rise, and never come back down fully, you lose your ZOA because you are now living with your ribs up. This position ensures that your lower back is over-arched (extended), your abs are not positioned to engage correctly, and your diaphragms can’t pump.

“Ribs up” occurs with inhalation and rotational movements of the torso (rotate your torso to the right and the right ribs should rotate up while left go down, rotate left and the left ribs rotate up and right ribs down).

When the ribs stay up, and never rotate down fully, it becomes a problem because the diaphragm now loses its dome shape and isn’t in a good position to help you breathe.

The ribs should move up (and out) during inhalation, and come down (and in) upon exhalation. But this doesn’t always happen.

This “ribs up” position, and loss of ZOA, can occur on both sides or more frequently, just on the left side.

And the Point is?

If the ZOA is lost, it means that some muscles are no longer doing their jobs correctly and other muscles will kick in to help out. This is what we call compensations. We can live with compensations, but we’d rather not have to, because eventually the body won’t be able to compensate any longer and the body will change the way it works, and generally not for the better.

In a somewhat existential sense, when the compensations become too great, it’s like you are living in a different body. Bones have changed position, muscles have changed position and function. Breathing patterns have changed. Humans evolved to meet the demands of life in one way, but we have changed. Yet the demands of human life are the same. Something has got to give.

I lived for years with a body that could no longer compensate and was in constant pain. It was horrible and depressing.

The Left Internal Obliques

The zone of apposition and the pelvis are the core of the human body. Together, they permit true tri-planar movement. If the zone of apposition is lost, so too will true tri-planar movement.

This is not to say that you will no longer be able to move your arms, legs, thorax, and neck. It just means they won’t move as fully or as effortlessly as they would if you had full control over your zone of apposition. A proper ZOA ensures that your thorax and pelvis are stable enough to permit limbs to move easily and powerfully.

The picture to the right shows, chiefly, the left internal obliques. What you will notice is its rather large area and most importantly, where the obliques attach

  • to the pelvis
  • left obliquesto the ribs

These attachment sites relate to the zone of apposition because they move the ribs down and rotate them to the left, thereby ensuring the integrity of the ZOA.

They also prevent the ribs from excessively elevating and rotating right during breathing and any movement that requires rotational movement of the torso, such as walking.

So not only do the internal obliques move the rib cage to the same side, they also prevent excessive movement when the movement is going to the opposite side.

The left internal obliques (and the transverse abdominis which lay underneath) help maintain your ZOA.

Without left internal oblique and pelvic strength I wouldn’t have been able to what I did in the test pictured in the beginning of the post.

When the left internal obliques lose the ability to

  1. Bring the ribs down.
  2. Prevent the left rib cage from rising excessively during movement and breathing,
  3. Hold the left ribs down while rotating to the right

You have lost your ZOA.

this picture is of elevated left ribsIn the picture to the right, you will see what this loss of zone of apposition actually looks like in my 13 year old niece. I have labeled the rather prominent and elevated left ribs. This is what happens when the left internal obliques can no longer hold the left ribs down towards the pelvis, even at rest.

The Compensation System

A loss of ZOA is part of an overall compensation system that produces compensational movement of the feet, legs, pelvis, rib cage, arms, neck, and head.

If you examine the ZOA diagrams again, with a loss of ZOA you’ll find:

  • A lower lumbar spine with increased lordosis (the natural curve in your lower back).
  • A middle back (thoracic spine) that has lost its natural curve and has become flatter.
  • A neck that has extended forward into a more forward head posture. This will alter normal neck rotation and side-bending movement.
  • Shoulder blades (scapulae) that don’t rest correctly on the rib cage, which can lead to altered shoulder joint (glenohumeral) position and function.

I haven’t even addressed what could go wrong with the pelvis, femur, knee, tibia, ankle, and foot. The lower body doesn’t just hang out all happy and content while the upper body potentially suffers.

Some people live quite normally with these compensation patterns. It’s likely that there is a degree of natural compensation tolerance built into human existence.

The problem occurs when the body’s natural asymmetries become too great, and the compensation patterns become too extreme, that detrimental effects start to appear, often in the form of joint and back pain.

How do we Reclaim Our ZOA?

Reclaiming our ZOA always starts with addressing a forwardly rotated left pelvis.

We do this through pelvic repositioning exercise such as this (this is one of many)

Once that has been done, we work on establishing the left ZOA by incorporating the left obliques into our lives. Then we have to tie everything together so that we can keep our ZOA intact while walking, running, jumping and whatever else we choose to do.

Our ZOA is first exhibited through regaining neutrality in our upper body. Neutrality means that our rib cage/spine is positioned in a way that allows freedom of movement in our arms and neck. It our rib cage was positioned in a non-neutral position, certain arm and neck movements would be limited. Our movement ability is displayed through Postural Restoration® testing. If PRI testing displays lack of movement (and it almost always does) we reposition the pelvis first.

  • a picture of a pelvis and femur oriented to the right.
    Pelvis and femur oriented to the right.

Sometimes repositioning the pelvis also establishes a ZOA and the upper body tests clear up at the same time. This can happen because the exercises used to reposition the pelvis puts you into a position that facilitates the left internal obliques and inhibits (turns off) other muscles, at the same time.

If the tests don’t clear up then you work on getting the rib cage and spine neutral through more specific upper body exercises.

The Test

While the tests I mentioned tell you if neutrality has been achieved, they don’t tell you if you can maintain neutrality while moving. That is what the Hruska Abduction Lift Test is for. It tells you if you can maintain a ZOA during dynamic movement on top of a neuro-muscularly strong left hip. The important thing is that the strength exhibited through the Lift Test is done without compensation.

Upon first glance, for any athletic minded person, the test doesn’t seem like it should be too difficult. But I’ve seen many a strong men and women quiver and shake in a futile attempt to score even a 1 on a scale of 1-5.

It’s not because these people weren’t strong. It’s because the position of their pelvis wouldn’t allow non-compensatory movements to occur. The only way they could possibly perform the test was to use compensatory movements. When they weren’t allowed to compensate, they were stuck.

  • Hruska Adduction Lift Test
    Gina can lift her left knee, but she can't get her bottom hip off the bench. She hasn't yet developed strength in her pelvis and internal obliques.

In the pictures I show two of my clients who used to suffer from knee and lower back pain. You’ll notice they are able to lift their bottom knee off the ground while holding their ankle to the knee. This is step #2 of the test. What they can’t do is lift their bottom hip off the bench.

Fortunately for them, just achieving a lift test score of 2, which indicates better pelvic alignment and the ability to adduct a left leg (and abduct a right leg without compensation) was enough to relieve them of their pain.

The big strong people I mentioned before, including collegiate strength and conditioning coaches that I was in a seminar with up in Boston two summers ago, couldn’t even lift their bottom knee off the bench without the usual compensation patterns of rolling their body backwards or over-arching their lower back in futile attempts to adduct that left leg. The reason they couldn’t even lift the left knee was because their left pelvis was stuck forward, and this pelvic position wouldn’t allow the left leg to adduct.

My clients got past the first step because we had already repositioned their pelvis so that it allowed true left leg adduction (bringing the left leg up off the bench).

When you can get to the position that I exhibit, (my goal for all my clients) you know you have a strong pelvis and a left ZOA. A strong pelvis and a ZOA provide:

1. A stable foundation off of which our appendages can move efficiently and powerfully.

2. The proper alignment for our spine, SI joints, hip joints, and shoulder joints. Misaligned joints, and the movement dysfunctions that result, are a major source of pain that doesn’t seem to have any physical causes. In other words, MRI’s and X-Rays don’t show any obvious or abnormal physical damage to the joints, yet pain exists.

3. Proper breathing patterns. Without a ZOA, your diaphragm won’t be positioned correctly to be the primary muscle of respiration. Other muscles of the lower back and neck will start to help out too much which can cause all sorts of problems, including lower back and neck tightness and pain.

Achieving a strong pelvis and ZOA doesn’t take care of every physical pain, but from my experience it does take care of a lot. Most people I’ve helped have suffered from SI joint pain, knee pain, and shoulder pain.

These three joints are directly influenced by the position of the pelvis, spine, and rib cage, so it’s no wonder that getting these structures into their natural positions helps clear up pain in those joints.

Chronic pain effects an estimated 100 million Americans, and I know this information could help them as it has helped me and my clients. Please consider clicking on the Facebook or Linkedin icons on the left to help spread the word.





  1. Robert says

    Hi there,
    What type of PRI exercises would you give to those of us who can’t lift the bottom hip up off the mat?

  2. Naoki says


    I had a difficult time understanding the concepts of ZOA but your article explained all very well!!
    Thank you so much

  3. Brad Baker says

    These blog entries and videos have been a tremendous help. I had lost my ZOA and was having and was staring down the barrel of a cervical fusion surgery. You helped me remember what I had been taught in PRI therapy. I required my ZOA one night and my world changed. Keep up the good work.

    • admin says

      Thanks for the kind words, Brad. Happy to hear about your re-discovery of the ZOA. If you can keep a ZOA, particularly on the left, it means everything is lined up and working correctly. The neck is so often a victim of ZOA loss since the spinal compensations travel up the chain from the lumbar spine all the way to the cervical spine.

  4. Christine says

    I have always had back, sholder and neck pain.

    My right hip is higher then the left and my rib cage sits lower on the left. My left hip flexors are always in tight and in pain too.

    Thoughts on what could be going on?

    Please any info would be helpful!

  5. maureen thomson says

    Thank you so much for this incredibly informative article. Following a recent shoulder injury (& historical knee problems & general hypermobility) I have just read this article and so many of my problems now make sense. Despite my regular & advanced yoga practice – I was still prone to injury & some weakness – I feel really excited at the prospect of reclaiming my ZOA! In addition to this – I have been playing the flute for 10 years+ and have struggled so much with having enough breath to play well- & now I understand why – so can’t wait to see the effect on my flute playing. Thanks again for sharing your amazing knowledge and insight. Maureen

  6. Kate says

    It is possible for someone to be stuck in left stance? Everything I’ve read about PRI is focused on right side dominance… My right hip is almost always higher and rotated forward compared to my left. I have tried massage, PT, chiropractic appointments and the re-alignments never last. (I have also had a series of injuries on the right side. Torn labrum. Broken ankle. Hip and groin pain.)

    • admin says

      Hi Kate,

      A hip can be higher on the right even when stuck in right stance. It won’t always be that the pelvis is higher on the left when stuck in right stance. A tight right QL (which is very common with a forwardly rotated left pelvis) can cause the right hip to be higher.

      In other words, the side of the pelvis that is forward doesn’t necessarily correlate with which side is higher.

      I have had some people ask me the same question, about being stuck in left stance, because they also thought their right side was rotated forward, but it turned out that what they saw visually wasn’t what the tests showed. Sometimes looks can be deceiving. That’s why PRI uses objective tests.

      That’s not to say that it can’t ever happen, but apparently it’s rare. I’ve never seen it first-hand.

      If you can get to a PRI provider, I’m sure they can help. Right sided pain is actually easier to deal with than left sided pain.


  7. Susan says

    Hello! Great article and definetly helped me understand ZOA better. I’m taking my first course tomorrow in Myokinematic Restoration. I’m nervous but excited. I’m going through the recommended reading and your articles have truly helped.
    Thank you!

    • admin says

      Awesome! PRI can be very confusing and overwhelming in the beginning, but it is well worth the investment in time and money. If you have any questions about what you have learned, don’t hesitate to e-mail me.


  8. Fredric says

    How long will it take until I should see some changes in my external rotated left ribs after doing the 90/90 hip lift? I see some changes in my pelvis and lumbar spine but my left ribs just wont rotate back internally to the right again. Do I need some more patient? Will it help to strengthen my left internal obliques and the core in general to bring my rotations back to normal?


  9. Cindy says

    This is life changing information! I just couldn’t explain it to anyone, family, doctors, PT, chiro. I know it was there at one point and couldn’t figure out what mind body connection had been lost. This information alone has already made a difference in my recovery. Thank you so much!

    • admin says

      Great to hear Cindy. Finding a PRI provider will greatly help your recovery since PRI can get quite complicated.


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