top of page

What is the Left AIC of the Postural Restoration Institute?

The Left AIC: What is it? Are you a left AIC? Is it the cause of you problems? Can you fix the Left AIC?

If you are looking for answer to those questions, you are in the right place

So, what is the the left anterior interior chain or Left AIC?

Well as the name suggests, it is a chain of muscle on the left side of your body. It consists of 6 muscles that run from the lower ribcage down the leg - Diaphragm, Psoas Major, Iliacus, Biceps Femoris, Vastus Lateralis & TFL - and these 6 muscles on the left hand side are more concentrically oriented (“tighter”) than their right sided counterparts. This is what we call muscular asymmetry.

Now with this muscular asymmetry comes joint asymmetry, and in the Left AIC you have a turn of the pelvis to the right. The left hip is slightly more forward, and the right hip is slightly more backward, which gives the pelvis a right shift.

This is essentially what the Left AIC is - the muscle and joint asymmetry of the body below the level of the ribcage.

So are you a Left AIC?


If you are human, then yes you are a Left AIC? We can know that because the foundation of the Left AIC is the diaphragm, and anatomically, everyone has a right diaphragm that is much larger than the left, and a right diaphragm that is not able to shorten to the same degree as the left diaphragm. Having a smaller, more concentric left diaphragm has flow on effects above and below, and it’s this that leads to the muscular and joint asymmetry of the Left AIC.

Does this mean everyone will have the same asymmetry?


Some have more tension, more of a turn, a different turn, the opposite turn even. Through breathing, movement, loading, different lifestyles, physical trauma or even mental trauma, we can all twist our bodies up into different shapes, we can tighten muscles on the right side, we can have our pelvis turn a different way, however foundationally because of the nature of the diaphragm, we are all a Left AIC.

So is it the cause of your problems?

Well it’s not a simple yes or no.

Asymmetry is normal and good and in fact necessary for movement and for breathing and essentially necessary for life to even exist, so in that sense no the Left AIC isn’t the “cause” of your back pain or neck pain or whatever your specific ailment or performance issue is.

But can a Left AIC - can our asymmetry - play into our pain experience?


How I generally describe it is like this - imagine you have a pendulum swinging left to right, and this pendulum represents asymmetry. Dead centre of that swing is neutral or complete symmetry. Nobody is neutral (neutrality is impossible) so we are all somewhere away from the centre. We could call a “healthy” Left AIC when you exist slightly to the left of neutral. This is a good place to be. However again through our breathing, our movement, how we load, our lifestyle and trauma, we can end up exaggerated in our asymmetry and begin moving too far away from the centre. This is not a place we want to be. The further you get, the more likely it is that you will begin experiencing pain and injury, and if you already have chronic back pain for example, then we can be almost certain that you have moved too far from neutral.

It’s in this way we can see the Left AIC is interplaying in our pain experience.

So then can we fix a Left AIC?


I can’t, you can’t, no one can, and it should already be clear why - because its not a problem, therefore not something to be fixed. Asymmetry - the Left AIC - is normal and good and again necessary for movement.

But… can we bring you closer to neutral?

Yes absolutely.

…and by decreasing your asymmetry could we resolve your pain or injury and have you move better?


To do that, you must start at the foundation which is again, the diaphragm and breathing. You get that right you’ll get the rest right.

So I hope this has helped you understand a very interesting but easily confusing subject. The people at PRI are very clever and it can take time to understand their concepts, but once you do it really does make a difference to how you understand the body, your own body, and the conditions and symptoms you have.

12 views0 comments


bottom of page