In gravity minimized MMT for Shoulder Horizontal Adduction, which shoulder rotation is used?

In gravity minimized MMT for Shoulder Horizontal Adduction, which shoulder rotation is used?

• A. Neutral Rotation
• B. External Rotation
• C. Internal Rotation
• D. Full Rotation

Answer: (A)

The movement tested relies on how the arm’s rotation changes which muscles drive horizontal adduction when gravity isn’t helping or opposing the motion. In a gravity-minimized setup, you want the arm supported and the rotation to be neutral so the primary adductor can produce the movement without extra contributions from rotator cuff muscles. Neutral rotation is used because it aligns the humerus in a way that the adduction vector across the chest is driven mainly by the pectoralis major, without the line of pull being biased by internal or external rotation. If you externally rotate, the movement begins to involve the external rotators and the pull changes direction, making it harder to isolate adduction. If you internally rotate, internal rotators (like subscapularis) contribute more, again shifting the focus away from pure horizontal adduction. A full rotation isn’t standardized for this test and would mix in varying amounts of internal/external rotation, obscuring the measure of the adductor’s capacity. So, neutral rotation best isolates the horizontal adduction effect in gravity-minimized testing.

The movement tested relies on how the arm’s rotation changes which muscles drive horizontal adduction when gravity isn’t helping or opposing the motion. In a gravity-minimized setup, you want the arm supported and the rotation to be neutral so the primary adductor can produce the movement without extra contributions from rotator cuff muscles.

Neutral rotation is used because it aligns the humerus in a way that the adduction vector across the chest is driven mainly by the pectoralis major, without the line of pull being biased by internal or external rotation. If you externally rotate, the movement begins to involve the external rotators and the pull changes direction, making it harder to isolate adduction. If you internally rotate, internal rotators (like subscapularis) contribute more, again shifting the focus away from pure horizontal adduction. A full rotation isn’t standardized for this test and would mix in varying amounts of internal/external rotation, obscuring the measure of the adductor’s capacity.

So, neutral rotation best isolates the horizontal adduction effect in gravity-minimized testing.