Horizontal Abduction Test and Air

The horizontal abduction test is a frontal plane PRI test for the right brachial chain.

An inability to horizontally abduct the arm beyond 30 degrees indicates a right brachial chain that needs inhibition.

But as with all things PRI related, there is a lot more to this test than meets the eye.

In PRI world, there is no more difficult a skill to be found than the ability to stand on your left leg, breathe comfortably, and reach with your left hand across the midline of your body without any type of compensatory muscle activity occurring (knee straightening, lower back extending, neck extending).

Not coincidentally, this is the same skill that virtually all PRI exercises are leading us towards: increase our ability to shift into left stance, stabilize left stance, breathe, and reach.

The reason this left stance position is challenging is because humans aren’t designed to do it as easily on the left as we are on the right. While there are other factors, the big player is the respiratory influence and dominance of the larger right diaphragm compared to the left.

Think of it in these terms: as long as we are alive, breathing, and living here on earth, this right sided dominance will always be the case (in space, without having to contend with gravity, perhaps the challenge would not be as great, but that’s a speculative thought)

In PRI, the “why” always comes back to this respiratory and neurological truth: we operate more easily on our right side than we do on the left, regardless of handedness. This inherent rightward bias can becomes so strong, so patterned, that we lose the ability to center the mass of our body to the left.

Instead of truly shifting from left foot to right foot and back (i.e, walking), we use compensatory strategies to make up for the inability to fully shift into our left side. When our body decides that the compensations have exceeded its limits, we may start to hurt.

The question becomes this: what is preventing us from overcoming our rightward bias so that we can achieve a left ZOA and true left stance?

In other words, what is keeping us over to the right and prevents us from getting back to the left?

As trainers and muscle enthusiasts, we can easily get seduced by the aesthetic beauty of the pec muscles and their considerable bench pressing power.

Justifiably, due to the amount of pressing exercises we do, the pecs are muscles generally thought to be in need of stretching.

But what escapes our awareness is what lays underneath and gives those pectorals their form and shape, is….

air.

Never in my life did I consider the role of air in strength and conditioning and movement before finding PRI. It just isn’t addressed much, if at all.

Given the proper amount of air, our spine is capable of amazing feats of rotational transverse movement, allowing us to look around to see what’s behind us, throw a baseball, practice martial arts.

On the other hand, put too much air into one or both sides of the ribcage and that transverse (and frontal) plane movement will be extremely challenging to accomplish in a smooth effortless fashion. You will still rotate, but perhaps not through the proper spinal segments and not without great strain.

The usual situation found in the Left AIC/ Right BC pattern is one where there is too much air on the left side and too little on the right, resulting in a state on inhalation on the left and exhalation on the right.

In this situation we are unable to truly shift our center of mass–our head, torso, and pelvis–over our left leg and foot.

We can’t get our pelvis and spine to fully orient to the left. We can’t fully achieve trunk rotation to the right (Right AIC/Left BC pattern)

If the above is not occurring, we are not, in a true biomechanical sense, on our left foot.

Our center of mass is never fully lateralized to the left. We may think we see left lateralization, but as philosophers and scientists know, our sense are limited. Appearances are deceiving.

It takes an experienced and very discerning eye to notice the little details, the “tells” that betray the appearance of left stance.

This is a really, really, important point. It is very easy to think we see left lateralization, meaning that we move our center of mass over the left leg, when in reality part of us is still over on the right. It is easy to be fooled visually.

Quite often, it’s the air in our left chest wall that keeps us right.

In the absence of reliable visual observation, we can look to the horizontal abduction test to indicate the ability of an individual to fully lateralize their center of mass to the left because it demonstrates how much air is on the left side. If you can’t get the arm past 30 degrees, you still probably have too much air in your left side.

In order to truly shift into left stance, to make sure that your center of gravity is truly over your left foot, your spine needs to orient to the left, which means you need to have a full left ZOA.

To have the left ZOA, you have to get full rib internal rotation on the left.

But getting this full rib IR on the left can be difficult on many people due to various areas of restriction that all have their origin in…

….the respiratory influence of the right diaphragm that biases us to the right over 20,000 times a day!

As an aside, it’s easy to get a “pseudo left ZOA”. You do some repositioning exercises, get the upper body tests to change a bit, you get close to 90 degrees of HG/IR and about 30 degrees of horizontal abduction and you think you’ve got it made. But things don’t seem to be clearing up for you client. That horizontal abduction test should easily get up to between 40-50 degrees or more, if you get all the air out!

The amount of air in the thorax determines the form the thorax assumes.

This fact can easily be seen as you breathe. Your ribcage expands as you inhale and your ribcage contracts as you exhale.

A ribcage on the left that is in a state of inhalation (rib external rotation) will be fuller than the ribcage on the right side that is in a state of exhalation (rib internal rotation)

Sometimes we do have tight pecs, especially if we do a lot of pressing exercises. In this case, stretching of the pecs is likely a beneficial thing.

However, an arm that doesn’t fully horizontally abduct is probably not being restricted by a “tight” left pec in most cases. The horizontal abduction is being restricted by air.

Look at the picture above. The ball on my left reflects the amount of air in my over-inflated left chest-wall. The ball on my right reflects the lack of air and restricted nature of my right chest wall.

In the horizontal abduction test, the left pec seems tight but it is actually taut!

Due to the increased distance it has to travel over the hyper-inflated left ribcage. There is no more slack left in the left pec to allow more horizontal abduction of the left arm.

It’s already at the end of it’s own rope, so to speak.

The right pec doesn’t have to travel as far to make it over to the right arm, thus there is plenty of slack in the muscle and the arm will horizontally abduct more than the left. This is the reason that a normal finding is to have more horizontal abduction on the right than on the left.

To equalize horizontal abduction, you have to get air out of the left side and into the right side, not by stretching.

Getting a full Left ZOA, via the ingenious Mermaid exercise pictured at the top of this post, forces the air out of the left side of the ribcage so that you can fully IR your left ribs and now fully lateralize over to the left.

And trust me, this lateralizing over to the left is not just some esoteric PRI-speak. It’s a real thing and it produces real physiologic change.

Finally getting fully left lateralized will often make you feel different.

I felt like I was heavier on my left leg and I definitely got more cranial expansion on the right. My left internal obliques were on fire, as well.

Some people feel lighter.

Some people feel like energy or warmth has rushed into the left side. They may feel their left hamstring kick in and feel more grounded.

A few people I used the Mermaid exercise with (people who were stubbornly stuck over to the right) felt an intense feeling of sleepiness afterwards.

In fact, one woman decided to head off to the mall following her workout but was forced to take a nap in her car before she started driving.

From a physical standpoint, her workout wasn’t that difficult, but from a physiological and neurological standpoint, it put her nervous system through the ringer. It’s like her brain was finally alerted to the fact that she actually has a left side

PRI exercises, when performed correctly, can be completely exhausting  in this way.

The amount of air in the thorax determines the form the thorax assumes.

This fact can easily be seen as you breathe. Your ribcage expands as you inhale and your ribcage contracts as you exhale.

A ribcage on the left that is in a state of inhalation will be fuller than the ribcage on the right side that is in a state of exhalation.

If the ribs on the left never get fully into internal rotation, meaning you never get a left ZOA, then you are left with a hyper-inflated left chest and an under-inflated right side.

While you may not recognize this visually, when you have less horizontal abduction on the left side than the right side, this is why.

Your prior education and mindset may lead you to believe that the left pec is tight and needs to be stretched (I’m guilty of this), but in reality the left pec has too much air sitting in the ribcage beneath it and thus there is no more room for the arm to travel.

It has reached the end of its length because of the increased surface area of the hyper-inflated left side of the chest.

Getting a full Left ZOA, via the absolutely ingenious Mermaid exercise pictured at the top of this post, forces the air out of the left side of the ribcage and you can now thus fully lateralize over to the left.

And trust me, this lateralizing over to the left is not just some esoteric PRI speak. It’s a real thing and it produces real physiologic change.

Finally getting fully left lateralized will often make you feel different.

I felt like I was heavier on my left leg and my left internal obliques were on fire. Some people feel lighter. Some people feel like energy or warmth has rushed into the left side. They may feel their left hamstring kick in and feel more grounded.

A few people I used the Mermaid exercise with (people who were stubbornly stuck over to the right) felt an intense feeling of sleepiness afterwards.

In fact, one woman decided to head off to the mall following her workout but was forced to take a nap in her car before she started driving.

From a physical standpoint, her workout wasn’t that difficult, but from a physiological and neurological standpoint, it put her nervous system through the ringer.

Interestingly this same person also had a very difficult time walking down the stairs because her right-sided pattern of movement was so disrupted by getting air out of her left ribcage and fully establishing a Left ZOA and thus left stance for the first time.

PRI exercises, when performed correctly, can be completely exhausting  in this way.

The bigger ball on the left represents the hyperinflation of my left chest wall.

The smaller ball on the right represents the deflated right chest wall.

If you imagine a pair of pec muscles, starting at the zipper on my shirt and extending out in both directions to my arms, having to travel over the airballs, you can visualize that the left pec would have to travel further to reach my left arm. It is the greater surface area of my left chest wall, due to the extra air underneath that is increasing its size, that “shortens” the left pec.

It is expected that my left arm would have less horizontal abduction ability than the right side, not because the left pec is tight and the right pec is not, but because the left pec has to travel further to arrive at my left humerus, and thus is already at it’s end range of elasticity.