The rotator cuff is an essential group of muscles that stabilize the shoulder during overhead movements such as the tennis serve. These muscles are commonly injured by tennis players and weakness of the rotator cuff can lead to multiple shoulder pathologies such as impingement (subacromial pain syndrome), biceps tendinopathy, and glenohumeral joint sensitivity. The muscles that we treat most commonly in the physical therapy clinic are the supraspinatus and infraspinatus muscles, followed by the teres minor muscle. Strengthening these muscles can help prevent injury and improve climbing performance.
One common exercise to strengthen the rotator cuff is to perform shoulder external rotation with a resistance band. You can see this exercise being performed often at the gym or on the tennis court prior to people playing, but many people use incorrect or sub-optimal form. Performing this exercise with poor form can (at best) limit the benefits of the exercise and (at worst) lead to repetitive stress injuries because of muscle compensation.
The most common mistakes people make with this exercise are:
1. Not using a towel under your arm: Reinold and colleagues found that using a towel under your arm while performing this exercise improved infrapsinatus muscle activation while decreasing deltoid muscle activation, making the exercise more targeted to the rotator cuff.
2. Straightening the elbow during the movement: pushing downward with your forearm leads to compensation with the triceps and avoids targeting the rotator cuff near end ranges of shoulder external rotation. Instead, angle your wrist/forearm slightly upward to maintain exactly 90 degrees of bend at your elbow throughout the movement.
3. Moving your elbow across your body: keeping your elbow in place during this exercise will ensure proper rotator cuff activation and will also challenge the eccentric control of the shoulder external rotator. Focus on keeping the tip of your elbow pivoting around a single point when performing this exercise.
Watch the video below to see how to perform shoulder external rotation strengthening with proper form and how to fix these common mistakes. If you have persistent shoulder pain or rotator cuff weakness, schedule an appointment with the tennis and racquet sports specialists at Mend in Lafayette, Colorado. Our physical therapy specialists have extensive continuing education in treating shoulder and other orthopedic conditions, especially in tennis and other racquet sport athletes.