External rotation is an exercise that helps to strengthen the rotator cuff, a group of four muscles and their tendons. It is one of several effective movements for this area that, over time, can increase overall stability of the shoulder joint, improve range of motion and help prevent injury. The four muscles of the rotator cuff include the supraspinatus, subscapularis, infraspinatus and teres minor, which control the arm in different directions.
Using a secured resistance band or cable machine with light weight, bring the upper arm to the side of the body, elbow bent to 90 degrees. The forearm may be positioned across the body or directly in front of the body if flexibility is an issue. Keeping the upper arm in place, slowly begin moving the forearm outward. A good rule of thumb is to pause at the point where you have reached your fullest range of motion rather than try to force the forearm beyond its capability.
In the beginning, start with one to two sets of 10 repetitions per arm daily or every other day to familiarize yourself with proper form. Add sets and/or repetitions gradually as you become stronger.
All rotator cuff exercises should be performed with light resistance and the movement should be slow and controlled. While it is normal to experience muscle fatigue, you should never experience pain.
— Marjie Gilliam is a personal trainer and fitness consultant.