Proper setup for the Exernal Rotation Press Exercise

Question

here the following exercise (External Rotation Press) is suggested to strenghten the rotator cuff muscles:

The autor states that this exercises works all the rotator cuff muscles to a certain degree. My question is: why shouldn't it work only the external rotators (Teres Minor and Infraspinatus)? Which is the role of the other muscles in this exercise (and should we feel them)?

Another question I have is this one: how should I keep my shoulder blades? Is it fixed (for instance: retracted, neutral, depressed etc) or should it move during the exercise?

Answer 1

Jeremy Either (the guy in the pictures) isn't the most knowleable and trustworthy when it comes to human anatomy, but to his excuse when people talk about the rotator cuff they only mention it in two distinct occasions:

Strenghtening the rotator cuff = only external rotators exist

Injured rotator cuff = only internal rotators are the cause

It's a common trope of the fitness industry to view internal rotators as the devil's muscles that should never be trained or else your shoulders explode and fly out of the orbit.

So no, this movement doesn't train the internal rotation part of the rotator cuff in any way. If you want to train your internal rotators google armwrestling training.

Answer 2

Your rotator cuffs stabilises your head of humerus in the glenoid cavity. When doing that exercise, all the RCs got to work to make sure the head of humerus is centred in the socket. There needs to be a balance in the force coming from all the RCs.

I’ll list the muscles used in concentric phase of movement:

Step 1-2: Scapula retractors Step 3: External rotators Step 4: Scapula upward rotators

The other muscles will need to work eccentrically or isometrically to maintain integrity of the joint. If they don’t work, your arms will fall off (exaggeration).

Retract your shoulder blades slightly, I’m assuming you are starting from a scapula protracted position. Retract to bring it back to neutral. Don’t have to retract the shit out of it as so commonly advocated by gym bros. Reason being, you need to raise your arm. Your scapula needs to rotate upwards to facilitate that, together with your glenohumeral joint. So “locking” it in place is not desirable.