What Is The Rotator Cuff And How Do I Strengthen It?

Todd Sabol, MS, AT



The rotator cuff is a group of four scapulohumeral muscles that aid in movement of the glenohumeral joint (shoulder joint) throughout much of its range of motion. They are considered scapulohumeral muscles because of their origin on the “shoulder blade” and insertion on the humerus. The shoulder girdle is a ball-and-socket joint just like the hip, so it has three degrees of freedom, which makes it highly moveable. The issue with this, however, is the humeral articulation with the glenoid of the scapula. The bony anatomy of the shoulder causes it to be anatomically unstable. This instability is somewhat alleviated by the labrum, which helps deepen the socket, but the instability remains. So, what does this mean? The shoulder relies heavily on dynamic stabilization from muscles and tendons, which is offered primarily by the scapulohumeral muscles. The rotator cuff group offers vital stabilization and movement of the upper extremity. As said before, this group includes four muscles, all of which offer specific actions at the shoulder.

                  The four rotator cuff muscles or “SITS” muscles include: the supraspinatus, infraspinatus, teres minor and subscapularis, all of which form a “cuff” which helps to form the joint capsule at the shoulder.

The supraspinatus is the most superior of the rotator cuff, sitting atop the scapula. This is the only rotator cuff muscle which does not directly help with rotation. Its main action is to initiate arm abduction (taking arm away from the body) by assisting the deltoid.

The infraspinatus sits below the supraspinatus and spine of the scapula. Its individual action along with the teres minor is external rotation of the arm. This is commonly the muscle aggravated or injured during low bar back squats, pitching or overhead activities, just to name a few.

Working inferiorly, the teres minor sits below the infraspinatus on the shoulder blade. This individual muscle, again works with the infraspinatus to externally rotate the arm. It also is responsible for arm adduction, or bringing the arm towards the body. The majority of the muscle belly and tendon is covered by the deltoid muscle group.

The final rotator cuff muscle, the subscapularis, arises from a different area of the scapula. It sits in the subscapular fossa on the anterior (front) side. Its main responsibility is internal rotation of the arm, while also assisting the teres minor in arm adduction.

As we stated at the beginning of this article, although these muscles arise from different areas on the scapula, they all attach to the anterior side of the humerus. In addition to their individual actions, as a group, they provide the vital stabilization of the shoulder by holding the humeral head in that shallow glenoid cavity. This is a very commonly injured muscle group because of the responsibility they have in stabilizing this highly moveable joint. In this series of articles, we will talk about the causes of rotator cuff injuries, how to prevent them and how to rehabilitate them. If you have any questions, comments or concerns feel free to let us know and remember to always #HealByMoving.



Welcome back to part two of the rotator cuff article series. Last week we talked about the basic rotator cuff information; how it is a group of four scapulohumeral muscles that aid in movement of the glenohumeral joint (shoulder joint) throughout much of its range of motion. We overviewed the terminology, anatomical location and responsibilities of each individual muscle in relation to the shoulder. This week we will discuss common injuries that occur with the rotator cuff.

As I talked about last week, due to the high reliance on dynamic stabilizers and poor bony articulations, the shoulder joint is extremely prone to injuries. To name a few; muscle strains, tendinitis, multidirectional instability and impingement are all common pathologies at the shoulder joint, often involving the rotator cuff. The tricky thing with these pathologies is, they often are caused by one another and cause the next injury, almost like a merry-go-round, which can turn into a very vicious cycle if not taken care of correctly. So, before we talk about diagnosis, rehabilitation and treatment, let’s break each of these common injuries down and how the rotator cuff group is involved.

Any time an injury occurs there is always a specific mechanism, or reason for onset. It may not always be clear to us based on if it is acute or chronic, but the better idea we have of that, it can make identifying the problem much easier. At the shoulder it is often difficult to determine injuries due to the intricacy of the shoulder joint. So many structures run through the joint; tendons, bursae, bony structures etc, that if one thing occurs it can lead to the onset of other injuries. Let’s start with a simple rotator cuff strains.

Rotator cuff strains are increasingly common in sport, due to many overhead activities and reliance on arm movement and also the responsibility we put on the shoulder to perform many actions throughout daily activity. Strains of any sort occur because of tissue attempting to withstand a load it cannot and from there it begins to stretch or tear. Strains can be graded on a 1,2, or 3 scale depending on the severity of the fibers stretched or torn. For reference, we commonly hear a grade three strain referred to as a “tear” so again it all depends on the severity of the damage.

Tendinitis can occur with any tendon, so let’s talk about general rotator cuff tendinitis first. Tendinitis can occur from repetitive micro traumas or overuse of the muscle fibers in question. Any term that ends in the suffix –itis, is referring to inflammation. So, tendinitis in nature, is referring to inflammation of tendons from the chronic overuse or micro traumas. If not treated correctly this can lead to long term, more chronic issues such as tendinopathies. These are generalized as diseases or deterioration of tissue and can lead to constant pain. This deterioration is caused from the acute injuries not being tended to and then exacerbated by the poor blood flow to each tendon and in turn, lack of healing.

Another common pathology the rotator cuff musculature is involved in is impingement. This occurs when the space that the rotator cuff tendons run through becomes decreased. This space, called the coracoacromial space is occupied by the supraspinatus and infraspinatus tendons, in addition to other structures including, but not limited to the subacromial bursa and long head of the biceps. When this space becomes enclosed, structures begin to rub on each other during movement and this can cause the rotator cuff tendons to become inflamed. This inflammation causes further closing of the subacromial space and cause increased pressure on the tendons. Possible long-term complications from this can lead to increased instability, decreased range-of-motion (ROM) and labral injuries down the road. This decreased ROM, specifically with internal rotation can lead to increased stiffness of the posterior capsule. This can cause further issues including weakness of the dynamic stabilizers of the GH joint, poor biomechanics of the shoulder and improper rhythm of the scapula. This can cause overhead movements, throwing activities and general daily tasks to become increasingly painful and bothersome.

The final injury I would like to briefly touch on is subacromial bursitis. When rotator cuff impingement, tendinitis go untreated, chronically this can lead to increased inflammation of the subacromial bursa and a further decrease of the subacromial space.

All of these injuries are distinct in nature, but as you can tell they are interrelated. Common signs and symptoms of many of these injuries are also very similar. Popping, clicking and pain are among the most common and they can cause pain in the shoulder, scapular or upper arm regions. Keeping that in mind, remember that tendinitis can cause impingement, and impingement can cause tendinitis and bursitis. It can be difficult to differentiate between one or the other in the acute setting, but if you are suffering from shoulder pain I urge you to do this: think about which motions bother you, what kind of pain you are having and how long it has been going on. All of these things can make diagnosing your issue much easier and allowing the proper steps to be taken in order to relive your symptoms.



n articles one and two, the goal was to give you ground work for the basic anatomy and some common injuries that can occur at the shoulder joint, specifically with the rotator cuff. My hope is that you were able to use that information to gather a better idea of what may be happening in your individual situation. The final part of this rotator cuff series will give basic guidelines for acute injury care and layout a group of mobility and strengthening exercises that you can employ for various injuries and/or use for a warm-up or prehab routine. 

What To Do When You Have Pain?


First off, take a minute and think about what the pain is like, how severe it is, during what movements does it hurt and how long has the pain been occurring? These are very helpful in determining what the specific injury may be. However, knowledge of previous injury to the shoulder and mechanism of injury (how the injury happened) are extremely important as well. Next, note all of the other symptoms you have occurring: clicking, popping, redness, inflammation, numbness, tingling, weakness, diminished pulse etc. The more information you have, the better idea you will have of what your next step should be. My goal is to give you tools that can keep you out of the doctor’s office or clinic and be proactive with your injuries. So, take a look at the last two articles and try to match up your symptoms.


Now What?


I know you're tired of me talking, you just want the programming. Like I stated before, the routines will be slightly different depending on when they are used, but regardless, these can act as a great injury prevention warmup or rehabilitation technique. The overall goal of the programming is to restore and improve your shoulder mobility. Many times, we do not have the proper shoulder mobility and range of motion (ROM) before we add weight and resistance. Then we start to develop poor movement patterns because our muscles are trying to shorten and lengthen in positions where they are not as efficient. This can cause pathologic movement patterns, muscle imbalances and injury. So, I encourage you to look at and employ the mobility and stretching techniques in commonly. From there, once you feel comfortable, add in the strengthening movements. If you have any feedback, comments or questions about specific injury rehabilitation plans please contact me and always remember to #HealByMoving.



Passive Flexibility/Mobility (See video @toddsportsmed)

All completed for 30 seconds, preferably both arms.


1. External Rotation

2. Internal Rotation

3. Horizontal adduction

4. Shoulder abduction

5. Posterior capsule release



-Use as a prehab/warmup circuit: 1 round each exercise (both arms) for 10 repetitions.

-Use as a rehabilitation program: 2 rounds each exercise (both arms) for 15 repetitions.


A. External rotation (Shoulder in neutral, elbow at 90 degrees)

B. External rotation (Shoulder at 90 degrees, elbow at 90 degrees)

C. Internal rotation (Shoulder at 90 degrees, elbow at 90 degrees)

D. Internal rotation (Shoulder in neutral, elbow at 90 degrees)

E. Horizontal adduction

F. Band Face Pulls

G. Band Pullovers

H. Band Pull-A-Parts

I. Prone Scaption


If you liked these articles, check out:

Shoulder Stability Circuit

For More Great Articles On Injury Prevention Check Out Our Prehab/Rehab Page!


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