The subscapularis is an integral part of a functioning rotator cuff and often overlooked in favor of strengthening the external rotators of the shoulder.
The subscap is one of the 4 muscles that make up the rotator cuff, which are the SITS muscles – supraspinatus (SSM), infraspinatus (ISM), teres minor (TMin) and subscapularis (SScap). The major role of the rotator cuff is to keep the head of the humerus (the ball) centrally located in the middle of the glenoid (the socket). Individually the rotator cuff muscles assist with abduction (SSM), external rotation (ISM, TMin) and internal rotation (SScap). Subscapularis also has a major role in depressing the head of the humerus as the arm is lifted out to the front (flexion) and to the side (abduction) of the body. When the subscapularis fails to execute properly, it can result in impingment and/or rotator cuff dysfunction.
How to test Subscapularis:
- Lie face down on the ground and place a ball under your bicep.
- Bend your elbow and bring your arm behind your lower back.
- Keeping your bicep in contact with the ball on the floor, attempt to lift your forearm away from your back (internal rotation of the shoulder).
- An inability to lift the arm away from the back or inability to keep the bicep on the ball indicates a weakness of the subscapularis muscle.
- Repeat on the opposite side to see if there is a difference between the right and left shoulders.
If you have difficulty and/or pain with this movement, it is likely that your subscapularis is not functioning correctly. This test can also be used as an exercise to improve the strength of the subscap, so try adding it into your shoulder stability routine. As with everything, it’s always best to get a professional to check you out!