The shoulder is an incredibly mobile joint but is also quite prone to injuries. One of the many ailments of the shoulder includes shoulder impingement syndrome (SIS). Some nicknames for SIS include the painful arc or swimmer’s shoulder (Anderson and Parr, 2009, p. 415). People who suffer from SIS usually have participate in lots of overhead and pressing movements, have over developed upper trapezius muscles compared to the middle and lower trapezius muscles, weakness and tightness of infraspinatus and teres minor, and have weaknesses throughout the scapular stabilizers and postural muscles.
SIS involves several different structures within the shoulder including the rotator cuff, acromion, subacromial bursae, and coracoacromial ligament. The aforementioned structures are defined as:
Rotator cuff – a group of four muscles that include the supraspinatus, infraspinatus, teres minor, and subscapularis. All of these muscles attach from the scapula (shoulder blade) to the humerus (upper arm). The rotator cuff is the main stabilizer of the shoulder to keep the shoulder in place in the socket.
Acromion – a specific point on the scapula. The acromion wraps around the shoulder and attaches onto the clavicle (collar bone). The acromion is near the superior (top) portion of the deltoid.
Subacromial bursa – a bursa is a fluid filled sac that helps reduce friction between tendons and bones, tendons and skin, and ligaments and bones (Anderson and Parr, 2009, p. 136). The subacromial bursa is underneath the deltoid and the acromion.
Coracoacromial ligament – a ligament attaches one bony point to another bony point. The coracoacromial ligament attaches from the coracoid process on the scapula to the acromion.
During SIS, the supraspinatus muscle and the subacromial bursa of the rotator cuff gets compressed between the acromion and the coracoacromial ligament which causes pain and inflammation in the shoulder. Tears throughout the supraspinatus may occur. If the condition has been ongoing for many months or years the supraspinatus muscles may become thinner, can cause degeneration, or even a total rupture of the muscle (Anderson and Parr, 2009, p. 415). Other structures can be involved as well such as the glenoid labrum and long head of the bicep brachii tendon, but for simplicity this article will discuss the involvement of mainly the supraspinatus muscle.
Signs and Symptoms
SIS is caused by force overload to the rotator cuff muscles and bursa during abduction (raising the arm out to the side), forward flexion (raising the arm in front of the body), and internal rotation of the shoulder (rotating the shoulder and arm toward the body) (Anderson and Parr, 2009, p. 415). Pain usually occurs with overhead pressing, lateral and forward deltoid raises, upright rows, sleeping on the affected side, reaching across the body to touch the opposite shoulder, and reaching overhead.
Early stages of SIS may include localized pain and swelling over the supraspinatus tendon. Minimal pain is felt with activities and lifting but no restrictions or decreases in weight are seen. Atrophy (wasting away or deterioration) of the rotator cuff muscles could be beginning (Anderson and Parr, 2009, p. 416).
As the condition worsens more pain is felt during regular activities and lifting, especially during abduction and external rotation (rotating the shoulder and arm away from the body). More inflammation is seen in the surrounding areas like the biceps brachii tendon and subacromial bursa. The inflammation can lead to thickening of the bicep brachii tendon and changes to the fibers in the bursa. Some clicking may also be heard during certain movements (Anderson and Parr, 2009, p. 416).
In the later stages the pain has been chronic for many months or years. Significant weakness and drops in lifting weights may be present. Small rotator cuff tears are forming, instability in the shoulder, and noticeable atrophy in the supraspinatus and infraspinatus muscles are seen (Anderson and Parr, 2009, p. 416).
If you feel like you are having any of the aforementioned signs and symptoms, you need to consult with a physician to discuss the appropriate intervention. Placing ice on the painful areas for 20 minutes at the end of the day or after a workout can help reduce inflammation. Wait at least an hour between each icing session to avoid any frost bite. If pain is present, then heat packs or hot tubs should be avoided. Avoid any painful positions or exercises until you can consult with a physician.
Anderson, M., & Parr, G. (2009). Shoulder Conditions. In Foundations of athletic training: Prevention, assessment, and management (4th ed.). Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins.
Note: This article is intended purely for educational purposes. It is not intended to diagnose, treat, or replace advice from a qualified healthcare professional. Every person with an injury is different and needs an evaluation by a physician, physical therapist, athletic trainer, or qualified healthcare professional to identify any problems. Please consult a qualified healthcare professional if you are experiencing any of the signs and/or symptoms described.