What does this exercise really strengthen?…
Rotator cuff strengthening exercise in adduction is one of the most used in shoulder rehabilitation. However, some studies have shown that deltoid activation in this exercise is high (1), so it can help maintain the unbalance between rotator cuff and deltoid muscle and contribute to the superior humeral head displacement.
The superior humeral head displacement is a movement impairment observed in many shoulder problems, such as early stages of adhesive capsulitis or rotator cuff injuries.
In these cases, this exercise, like those that imply ABD or flexion with straight arms should not be prescribed: the high activity of the deltoid muscle does not allow the activation of the rotator cuff, needed to promote the lowering of the humeral head.
In order to strengthen the rotator cuff in these patients, it is better to choose exercises that minimize the deltoid activity, such as the Inferior Glide (2) or the external rotation exercise at 90º of flexion (3).
1. “Which is the optimal exercise to strengthen supraspinatus?” BOETTCHER CE, GINN KA, CATHERS I. Med Sci Sports Exerc. 2009 Nov;41(11):1979-83
2. “Electromyographic analysis of specific exercises for scapular control in early phases of shoulder rehabilitation” KIBLER WB, SCIASCIA AD, UHL L, TAMBAY N, CUNNINGHAM T. Am J Sports Med 2008 Sep; 36(9):1789-98
3. “Selective activation of the infraspinatus muscle” SUNG-MIN HA, OH-YUN KWON, HEON-SEOCK CYNN, WON-HWEE LEE, SU-JUNG KIM, KYUE-NAM PARK. Journal of Athletic Training 2013;48(3):346–352