What is the rotator cuff?

The rotator cuff, for most throwing athletes, is the most publicly discussed muscle group when it comes to injury, injury prevention, and training. The rotator cuff, in simplest terms, is a group of four small muscles that control how the head of the arm rotates, lifts, and controls certain movements. What is important to recognize is that the rotator cuff serves a limited function in generating or stopping force - while it is integral in those processes, that is not due to its ability to handle a high volume of force, but more in its ability to direct or control existing force.

The reason that it is important to discuss that function is because in many injuries or mechanical issues, the focus that ends up on the rotator cuff and its health is misdirected. We’ll examine one example. The shoulder blade is part of the shoulder complex, and is attached to the ribcage with muscular tissue. That tissue, the muscles that stabilize the shoulder blade, are very strong, and in some respects serve as the foundation of the shoulder and how it moves or doesn’t move. If that tissue that stabilizes the shoulder blade moves too soon and does not do its job, then some other tissue will need to compensate and pick up the slack: enter the rotator cuff. One way an athlete will compensate is to pass that force into the rotator cuff, meaning the rotator cuff is working overtime. In some cases, this leads to rotator cuff strains or biceps tendinitis. In other cases, the rotator cuff also turns down the force, and kicks the issue further down the chain to the elbow.

Staying with the rotator cuff, for the example: if the muscles that stabilize the shoulder blade (the big back muscles) don’t do their job, and therefore strain the rotator cuff muscles to the point of injury, what do most coaches, doctors, and physical therapists then recommend? Rotator cuff strengthening exercises. They’ll give you some bands, do some internal and external rotations, perhaps some instability training, and tell you to stop throwing for a while. And while this certainly isn’t a bad thing (strengthening the rotator cuff is highly recommended), it’s missing the root cause of the issue - the shoulder blade stabilizing muscles aren’t doing the job. And, when we recognize the limitations in volume of what the rotator cuff can actually handle, we can see that there is no amount of rotator cuff strengthening that will make up for losing the big back muscles that stabilize the shoulder.

So, the point I’m making here is that it’s important to recognize the importance of the rotator cuff, but equally important to recognize its limitations. Injuries at the site of the rotator cuff do not originate in the rotator cuff, generally speaking, and if you have pain from heavy throwing volume, rotator cuff work alone will not solve the problem. They are four small muscles with a limited ability to handle creating high volumes of force. Think of them as air traffic controllers, not jet engines. If you want the plane to move faster, address the engines, not the air traffic controllers.

Coach Drayson

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