Shoulder weakness is probably the most concerning shoulder symptoms to have, and here I’m going to show you how to test your rotator cuff muscles on your own. Other symptoms and signs like shoulder pain, loss of range of motion, and loss of function are things you might notice as well, but testing your rotator cuff for muscle weakness will give you a good idea what’s wrong with your shoulder.

Since we’re all about providing value to patients and educating them on what’s going on in their body, in this content we’re going to:

  • Show you how to test your own shoulder muscles for rotator cuff muscle weakness
  • Explain different reasons shoulder muscles get weak
  • Cover some of the shoulder problems that cause shoulder weakness

How to Test for Shoulder Weakness in the Rotator Cuff

Testing for rotator cuff weakness is an important part of identifying what’s wrong with your shoulder, and I’m going to show you how to do that here. But first, let’s do a quick review of the rotator cuff.

Your rotator cuff is made up of 4 muscles, easily remembered with the acronym SITS: Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis.

The job of the rotator cuff is the stabilize the glenohumeral (shoulder) joint and normal rotator cuff muscles should be strong and your shoulder should feel supported.

To test your own rotator cuff muscle strength, you’re actually going to need one other person. It’s a fairly simple process in which your helper will be pushing your arm in one way while you’re resisting their pressure in the other direction. If you’re unable to resist at all, or maybe can’t provide the same resistance compared to the other shoulder you have weakness in that rotator cuff muscle.

It’s always a good idea to test your good (normal feeling) shoulder so you can compare it to your suspected weak shoulder. Also, keep in mind that you may have pain or weakness in multiple muscles of the rotator cuff, this is not uncommon.


Maybe you’re not sure you have shoulder weakness but ARE sure you have shoulder tightness. Check out my content –> Dry Needling for Shoulder Tightness

If your rotator cuff IS weak, you may have a shoulder labrum tear (hopefully not!) Here’s some content I wrote about how to figure out if you have a torn shoulder labrum –> 7 Signs You May Have a Torn Shoulder Labrum


 

Shoulder Weakness When Lifting Your Arm to the Side – Supraspinatus Muscle Test

This video shows you how to test for shoulder weakness in your rotator cuff supraspinatus muscle. The supraspinatus (S in the SITS acronym) is the most common injured muscle of the rotator cuff. If you have pain lifting your arm to the side, overhead, or reaching out to grab something, the supraspinatus may be the affected muscle.

Shoulder Weakness When Rotating Your Arm Backwards – Infraspinatus Muscle Test

This video will show you how to test your Infraspinatus rotator cuff muscle (the I in the SITS acronym.) If your infraspinatus muscle is painful, you may have discomfort on your shoulder blade and in the back of your shoulder. If the infraspinatus muscle is weak, you may feel weakness when reaching behind your head or winding up to throw a football.

Shoulder Weakness When Rotating Your Arm Inwards – Teres Minor Muscle Test

This video will show you how to look for weakness in the Teres Minor (the T in the SITS acronym.) If this muscle is affected you may have pain in the back of your shoulder and at the outside edge of your scapula. If you have weakness, you may feel it when reaching across to touch the opposite shoulder or reaching behind you to touch your lower back.

Shoulder Weakness When Pressing Back – Subscapularis Muscle Test

This video will show you how to test the subscapularis shoulder muscle (the last S in the SITS acronym.) Typically this will produce pain underneath the shoulder blade or in the armpit. If you’re reaching back like when putting your seatbelt on or reaching into the back of the car you may notice weakness in this rotator cuff muscle.

Why Do I Have Shoulder Weakness?

If you’ve tested your own shoulder and you do have weakness in your shoulder, there a few things that can cause this.

Pain-Related Weakness – Your shoulder might be weak because it’s really painful to hold your arm against resistance. It may not be that you can’t hold against resistance, but that you quit resisting because it’s too painful.

Neurological Weakness – Neurological weakness may be part of your rotator cuff weakness. This is when you have a neurological component to your pain, injury, and weakness. No matter how hard you try to resist you won’t be able to.

Weakness from Injury or Tear – Weakness may be because of a partial rotator cuff muscle tear, a full thickness rotator cuff tear, or a number of other conditions which have damaged a rotator cuff muscle. When this happens the muscle cannot draw on its fibers and length for strength.

Sometimes you might have shoulder weakness for more than one of the above reasons. If you have rotator cuff muscle weakness, the next step is getting a full exam on your shoulder to figure out what’s causing the weakness.

It’s difficult to differentiate between types and cause of shoulder weakness unless you’re a chiropractor who works on shoulders frequently. Don’t try to self diagnose what’s wrong with your shoulder, guessing will make you paranoid and you’ll likely assume the worst.

What Shoulder Problems Can Cause Rotator Cuff Weakness?

Most causes of shoulder weakness and pain aren’t traumatic and develop over time. You’re probably familiar with the big causes of weakness (like rotator cuff tear) but less familiar with other causes. Here’s a list of the most common causes of shoulder weakness, keep in mind that it’s not an exhaustive list.

  • Rotator cuff tendinitis or tendinosis
  • Partial tears of the rotator cuff muscles
  • Complete tears of the rotator cuff muscles
  • Impingement syndrome of the supraspinatus muscle
  • Scapular dyskinesia and poor shoulder movement patterns
  • Moderate to severe shoulder arthritis
  • Adhesive capsulitis (frozen shoulder)
  • Shoulder labrum tears
  • Neuropathy
  • Cervical radiculopathy (pinched nerve in the neck)
  • Thoracic outlet syndrome

You can see there are a lot of potential things that can cause weakness in your shoulder, which again, is why it’s important to have a professional examine it. The good news is that most of these can be treated at our office without surgery. I recommend seeing a non-surgical provider, like a chiropractor, first. If it’s not something that we can treat effectively we’ll refer you to an orthopedic surgeon or someone who can.


One of the treatments I use a lot for shoulder pain is dry needling. If you want more information on this, see my content here –> Dry Needling for Shoulder Injuries

Shoulder impingement can sometimes cause shoulder muscle weakness in the supraspinatus rotator cuff muscle. Here’s some information on treatment for shoulder impingement:

–> Chiropractic for Shoulder Impingement

–> Dry Needling for Shoulder Impingement

Dr. Jason Williams DC is a chiropractic physician practicing at AccessHealth Chiropractic in Cary, NC. He treats neuromusculoskeletal pain and injuries using chiropractic manipulation, dry needling, acupuncture, rehab exercise strategies, and other supportive therapies. Primary areas of focus include back pain, neck pain, muscular pain, extremity pain, and orthopedic injuries. Dr. Williams is experienced in treating athletes, especially those in the CrossFit, Brazilian Jiu-Jitsu, Muay Thai, and MMA community.

If you’re interested in whether he or another AccessHealth provider can help you, navigate to our contact page or follow this link to request an appointment.