How to Fix Your Left AIC Pattern - A Guide to Asymmetrical Posture & Movement

AIC - This stands for anterior interior chain and usually affects the left side. This is the most basic pattern developed when our body starts to get into poor postures or move in less than ideal ways. Our diaphragm is the muscle that connects our thorax to our lower back and is the primary muscle of inspiration.

The Left AIC is a term established and founded by the Postural Restoration Institute (https://www.posturalrestoration.com/)that has gained a lot of popularity over the last few years. It effectively explains how humans are naturally asymmetrical and how that matters for, well, everyone.

If you'd rather watch than read, see the video below:

Click Here: https://youtu.be/KQI3-SiMHFM

If you would like an even quicker recap, check out this explanation below of the Left AIC Pattern in 3 minutes:

Click Here: https://youtu.be/eJbsKjx8teE

What it ultimately comes down to is that we favour our right sides and our asymmetrical nature puts us in this position (yes, even if you are left-handed).

This is completely normal and not a problem at all, but what matters is that this asymmetry can be exacerbated by poor breathing, postural integrity, and lifestyle habits like sitting too long.

Why Do We Start In A Left AIC?

For one, our organs are not symmetrical:

Our right lung is bigger than our left

Our liver is a large organ which sits predominantly on the right side

Our diaphragm, a main muscle of inhalation, is larger on the right

This is important because the body is primarily concerned with survival. In order to survive, our body naturally orients to bringing air in the easiest and most energy-efficient way possible.

There is some research on this as well:
This study found that there is a normal rightward orientation of the human spine
https://www.academia.edu/27022586/The_Relation_Between_Organ_Anatomy_and_Pre_existent_Vertebral_Rotation_in_the_Normal_Spine
This study found that there is a normal right side-bend in the human spine
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3032747/
It is a bit more complex than this, but to keep things simple:
If we are leaning on our right sides, our right ribs are going to be oriented down and won’t open as easily as our left. Therefore, our body will orient in a position that’s most efficient to bring in air, with the left chest wall open:

Of course, what I do here with my body showcases an exhilarated body state! But please, see for yourself in clients' pictures below and observe the left AIC and right BC patterns for yourself.

The left side is opened up via pelvic orientation to the right and our trunks (relatively) to the left so we can really breathe into our left chest.

Due to the fact that it is sometimes challenging to observe and often difficult to assess independently, the initial step in my program is a posture assessment. This involves performing movement tests and capturing standing pictures from all sides to provide a more accurate understanding of your current rotational state in the body.

If you're looking for a deeper dive on these concepts, check out my Beginner Biomechanics Course - Unlock Your Body's Potential Posture Restoration Stage 1 & 2 - On Our Interactive App. You will start of with the posture assessment in the app.

Unlock Your Body's Potential Posture Restoration Stage 1 & 2 - On Our Interactive App. You will start of with the posture assessment in the app.

Essentially, your body will take the path of least resistance to bring in air, which makes sense given it is quite literally the most important thing a human needs.

The result is a right side that is biased towards:

Internal Rotation
Adduction
Extension

And a left side that is biased towards:

External Rotation
Abduction
Flexion

Brain Asymmetry

In addition, our brains are not symmetrical, but it runs deeper than most people think. Research suggests that the left hemisphere, which controls the right side of the body, is dominant in motor planning. This helps explain why most people are right-hand dominant.

The net effect is a bias towards the right side, which usually presents as a tendency to shift our weight onto our right leg when standing and our right ischial tuberosity (“sit-bone”) when sitting.

If you’re sitting right now, try to feel your left and right sit bones. If you feel your right more than your left, you probably have this pattern in some shape or form.

If you still don’t believe me, stand up, put your right foot behind your left, and then put as much weight on your right heel as you can. Then, keep your pelvis turned to the right and try to rotate your trunk to the left just like the above picture. Now, reverse it and try the same thing with your left foot back.

I have a very detailed, free webinar here if you are interested learning more about these PRI concepts:

https://youtu.be/_EyTPYLu-Js

How To Tell If You're A Left AIC

I use a posture assessment and look for rotation in the hips and shoulders to determine if someone is a Left AIC.

Standing Picture

Take a dive into self-discovery by checking out how your standing picture compares with the balanced posture images. Join us in the webinar in this blog below link for a deep dive into your body's unique dynamics. See the cool differences and get your posture in sync for a life that's pain-free and totally balanced. Start this chill comparison to kick off your wellness journey!

How to take your standing pictures: https://youtu.be/vtkNWDUAt88

The first one is a one-person test, it's probably not that helpful for the average person reading this. But I would like to show it because it is the classic posture test that gives insight into asymmetry. Through going through the webinar below you can start to create awareness about posture.

How to read your Standing pictures: https://youtu.be/fGCfowO5rb8

Hip Flexion

This test measures internal rotation, flexion, and extension of the pelvis. We would expect the right side to be higher at this than the left, as I mentioned above, the right side has more access to these joint actions.

This assesses external rotation of the pelvis and leg. The goal is about squat down without using your shoulders, neck or trunk, but we would expect the left side to be forward and down than the right side back and up (rotation in the pelvis):

Squat test: https://youtu.be/b36VW7WDaXE

Forward Fold Test

This assesses more rotation in the spine (scoliosis). We would expect the right shoulder to be rolling forward and down. The left shoulder back and down, as I mentioned above, the right side is locked at the front in the shoulder joint and left vice versa (back in the socket at the shoulder joint.

The goal is about to become more even and reduce the shoulder impingement of tilted shoulders.

Forward Fold Test: https://youtu.be/LNuXPKAX7Hk

Shoulder Internal & External Rotation

This is an upper-body test that assesses how well your scapula can glide on the back rib cage. Because the left side of the pelvis is more forward than the right, this causes more "compression" (tightness) on the back rib cage. Under normal circumstances, the further forward your pelvis is, the less shoulder flexion you'll likely have.

This is why the left side is more limited than the right:

https://youtu.be/K0TtsRnURSk

Exercises To Fix A Left AIC

If you find that three or all four of these assessments line up with the expected outcomes, then you are very likely in a degree of a Left AIC pattern. This means that you will very likely benefit from the exercises below. However, we can't assume that everyone is a Left AIC, as individual differences exist. This is simply a lens to appreciate how humans are built.

The goal of the right side in restoring a Left AIC pattern: Restore external rotation, abduction, and flexion via muscles that help accomplish that:

Glute max (external rotation + flexion)
Obturator Internus (external rotation)
Posterior glute medius (abduction)
Also, chest wall expansion to help pull the right shoulder back

The goal of the left side in restoring a Left AIC pattern: Restore internal rotation, adduction, and extension via muscles that help accomplish that:
Hamstrings (pulling pelvis back + internal rotation)
Obliques/Transverse Abdominis (pulling pelvis back + internal rotation)
Adductors (internal rotation + adduction)
Anterior gluteus medius (internal rotation)
Also, expanding the back ribs with air to help decompress that area

Try these drills and be sure to retest your assessment results.

Please remember: Execution is everything for these drills. If you do not have proper form, or just go through the motions without the right intent or feeling the right things, you won't get nearly as much benefit from these. The reason these exercises are so effective is because they are respecting so many different aspects of systems of the brain, skeleton, and muscles. My best advice would be to watch the video, then open it on your phone and listen to the audio and walk through it as I take you through the steps.

If you're looking for a deeper dive on these concepts, check out my Beginner Biomechanics Course - Unlock Your Body's Potential Posture Restoration Stage 1 & 2 - On Our Interactive App.

Unlock Your Body's Potential Posture Restoration Stage 1 & 2 - On Our Interactive App.

PRI 90/90 Supported Alternating Crossover: Left Foot on Wall

https://youtu.be/-Lsf9EdUbRU

PRI Right Sidelying Left Adductor Pullback

https://youtu.be/dfnCoJ-PAyE

PRI Sit & Reach With Left Arm To Improve Scapular Range of Motion

https://youtu.be/MV_tMRWBgJ4

PRI Left Side Lying Right Glute Max

https://youtu.be/BAmB3YIgIIQ

References:

Chibulka, MT et al. Changes in innominate tilt after manipulation of the sacroiliac joint

in patients with low back pain. Physical Therapy, 1988; 68: 1359-1363.