In clinical physical therapy practice, I have noticed that rotator cuff exercises tend to have more of a bias towards external rotation rather than internal rotation. Why is this?
Here is an example of external rotation (see video below). This can be done either on one’s side as in the first video or standing with a cable or resistance band.
It is often true that the external rotators of the shoulder weaken with a forward posture. It is extremely common to see the desk jockey walk into our clinic and present with shoulder blades that are drawn out to the side and shoulders that are in an internally rotated resting position. We PT’s affectionately call this the “keyboard position,” as this posture does hold the patient over a laptop or at a keyboard for hours at a time. Strengthening the external rotators with this type of posture is generally a good idea.
So where does strengthening the internal rotators fit in to all of this?
The rationale for strengthening the internal rotators of the desk jockey comes into play as it relates to how the humeral head sits in the shoulder socket. A dysfunctional shoulder will sometimes “sit forward in the socket”: it will not easily rest back into the capsule. Over time, the posterior portion of the shoulder joint will become stiff and compound the problem. Reaching forward all day can create this problem in addition to the shoulder blade positioning problem mentioned.
The action of the internal rotators facilitates the posterior rolling of the head of the humerus. For this reason, it is a good idea for many patients to strengthen the internal rotators. The trick in prescribing this type of exercise is to get the patient to block the front of the shoulder so that the muscles are strengthened with a posterior roll of the humeral head. Take a look at how we typically prescribe internal rotation exercise below.