The Most Common Cause of Shoulder Pain & How to Fix It

There is a common cause of shoulder pain—and there’s a good chance it’s the reason your shoulder hurts.

A condition called shoulder impingement syndrome.

It can also go by names like:

  • subacromial impingement,
  • painful arc syndrome,
  • supraspinatus syndrome,
  • swimmer’s shoulder, or
  • thrower’s shoulder

And in the medical world shoulder impingement will sometimes get defined by the pathology of what’s actually hurt.  Things like rotator cuff tendonitis, biceps tendonitis, bursitis, or other medical ‘itis’ words.

It’s one reason why people get so mixed up about their shoulder pain.  There are a lot of words, all describing the same thing!

What is Shoulder Impingement?

Take a quick review of your shoulder anatomy (which you can dig into this a bit more HERE), for an important structure to point out.

There is a small gap in the shoulder called the subacromial space.  And Inside this space are muscles, tendons, and sacs of lubricating fluid.

For a long time, we considered the acromion to be the primary culprit of shoulder pain.  It was observed as a nasty hook that would grab onto and rough up tissue in the shoulder, to the extent that shaving or cutting the acromion became a common procedure.  But we’re now cluing in that “shoulder impingement” is actually supposed to happen, and with all shoulder movement, the tissues naturally glide between the bones of the shoulder.

But if it’s normal, then why does it hurt?

First of all, there’s not much room for error beyond the normal shoulder biomechanics. If shoulder function is thrown off, even just slightly, it will add extra compression to the tissues in the space.

Things like stiff and inflexible shoulders are likely to decrease the subacromial space…

Or if the scapula isn’t moving with the arm correctly, it can position the bony prominence too low…

Or if the rotator cuff isn’t doing its job to keep the arm stable in the shoulder socket…

All of these things will lead to a greater degree of shoulder impingement. 

If this extra compression happens while sipping a cup of coffee, it’s not likely to flare anything up (unless it’s already irritated).  But consider playing tennis, or throwing a ball, weightlifting, or painting a ceiling. 

It’s usually through a cocktail of shoulder mechanics, loads, speed, and volume that our shoulder ends up in pain.

Additionally, if something is irritated, it’s likely to hurt if you poke it.

For example, if you twisted your knee playing soccer, it’s likely to hurt for a few weeks if you bend it.  In this example, bending your knee causes pain, but it’s not the cause of your injury.

Likewise, even if impingement is normal, if you’ve irritated something in your shoulder, it’s likely to be bothered when it’s compressed.

So the impingement pain may be in response to other shoulder issues, like rotator cuff or labrum tears, that not only increase the degree of impingement but also make the shoulder cranky when it gets pinched.  

Thus, it’s too simple to say that impingement syndrome is caused by the compression of the tissues inside the shoulder.  Because by itself, that’s what’s supposed to happen.

Although the diagnosis…


is a hard one to say, so we’ll stick with shoulder impingement.

Tests for Shoulder Impingement

There are lots of assessments used to determine if someone has impingement syndrome.

A very simple one for someone to do on their own is to reach across the body and put the hand on the opposite shoulder.  Then lift the elbow towards the face and check for pain.



There is another assessment called a painful arc test.

For this assessment, lift the arm up away from the body, into an overhead position.  If there is pain between 60 and 120 degrees this is a positive test.


Shoulder pain during either of these tests would be an indicator that you’ve got some irritation that’s getting further irritated with impingement. Even if you check out on these tests, if you have shoulder pain, there is a very good chance that shoulder impingement is involved somehow.


And regardless, the corrective plan for shoulder impingement will help your shoulder, no matter the cause.

Which leads us to the next question…what to do about it?

Fixing Shoulder Impingement

If you want to fix your shoulder impingement, there are two big steps in order to get you there, which both involve lessening the degree of impingement.

The first is to lighten the stress on your shoulder,  By reducing the loads and volume on your shoulder, the shoulder impinges less and allows for some healing.  The best guide for this is to simply eliminate any painful movements.  This should make sense, but many continue to push through pain, which only makes matters worse.  As a general guideline, give it 2 good weeks of good shoulder rest.

Although the first step is for nothing without the second one—it’s critical and often missed or ignored.

The second step involves building shoulder strength and mobility.  This not only improves shoulder mechanics for less impingement but progressing through pain-free movement is an important part of getting past your brain’s perception of pain.  You can read more into this in our article End Your Pain by Retraining Your Brain.

These are the underlying principles of our 30 Day Shoulder Fix.

In this program, we walk you through a 30-day rehab program, designed to fix your pain and improve your shoulder strength and mobility, so that it never returns.  But it’s not always the right fit for everyone.  

Take our Red Flag Screen to determine if shoulder impingement is likely the cause of your pain and if our self rehab program is right for you.