Shoulder Impingement

The shoulder stabilizes the arm in all activities. Therefore shoulder pain can cause significant impairments in function and quality of life. Subacromial impingement is one of the conditions that causes pain in the shoulder and upper arm. The arm bone that connects to the shoulder is called the humerus. Imagine the top of the humerus as a golf ball and the part of the shoulder that it sits in as a golf tee. The rotator cuff muscles act to stabilize this golf ball on the tee to keep it in place as the arm moves in different directions.

If you follow the top of your shoulder blade out to the tip of your shoulder you will feel your acromion. The rotator cuff muscles wrap around your shoulder blade and pass under your acromion to attach on the humerus. The area under the acromion is called the subacromial space, and this is where the rotator cuff tendons can get irritated.

However there are other structures that also pass though this space, such as the tendon of the biceps muscle and the subacromial bursa, which is a fluid filled sac meant to decrease the friction of the shoulder joint with movement. These structures can also become irritated with overuse of the shoulder. Subacromial Impingement Syndrome (SAIS) is the term used to describe this irritation of the structures that pass through the subacromial space.

Treatment for SAIS

Physical therapy treatment of SAIS can include multiple interventions such as exercise, electrical stimulation, manual therapy, and patient education on proper posture. The goal of a treatment program is to relieve pain, promote healing, restore pain free range of motion, reverse abnormal muscle imbalances and increase strength. Stretching is important to improve healing of the tissues by decreasing stiffness and increasing elasticity of the tendons.

Posture can be an important component of shoulder pain. Forward head posture with the neck coming forward contributes to both neck and shoulder pain as the head places a greater force on the neck in that position, which can often refer down to the shoulders. This head posture is often accompanied by rounded shoulders which limits that subacromial space leaving the shoulder at risk for impingement. Over time, the rounded shoulders position can also weaken the back and rotator cuff muscles as they are constantly being stretched.

To change bad posture it is important to be aware of bad posture and know how to correct it. The ears should be directly over the shoulders with the shoulders down and back. When sitting at a desk, the elbows should be at your side at 90 degrees with the wrists in neutral and if possible your computer screen should be at eye level to prevent bending at the neck. In standing the head should be in line with the spine with the feet hip width apart.

Strengthening Exercises

Strengthening of the rotator cuff also is important in order to allow the muscles to control the movement of the golf ball (humerus) on the tee (shoulder joint). Isometric exercise is based around holding a muscle contraction in a certain position without moving the muscle. Imagine you have your elbows at your side bent at 90 degrees with a resistance band wrapped around your hands. If you were to move your hands away from each other, you would increase the resistance of the band. Holding that position for 30 seconds, with multiple repetitions, is an example of an isometric exercise.

Isotonic exercise, on the other hand, involves you moving your arms through your range of motion in order to strengthen the rotator cuff and build endurance of those muscles. Imagine laying on your stomach at the edge of your bed with your arm hanging off the side. Lifting your arm straight up toward your head 10 times is an example of an isotonic exercise. This exercise can be performed in different directions (moving your arm straight out to the side or back toward your feet) and can be progressed by adding hand weights.

Both isometric and isotonic exercises should incorporate stabilizing the scapula as well as strengthening the rotator cuff. The scapula should be thought of as the foundation for all shoulder movement. For every 2 degrees of movement you see at the shoulder, the scapula moves 1 degree. If this rhythm is off it can affect how the shoulder functions. Exercises such as squeezing the shoulder blades together can help strengthen the muscles involved in scapular movement to allow for a more efficient movement pattern at the shoulder.

Exercise, in combination with other interventions such as manual therapy, has been proven to be effective in reducing pain and improving function in individuals with SAIS. There are multiple ways to work these muscles, utilizing both isometric and isotonic work, and above are just a few examples of that. Exercise plans should always be specific to the individual’s needs and limitations and should focus on the goals of that individual.  For more information on physical therapy and all Total Performance services visit

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