Last updated: Oct 18, 2021

Anatomy & Background

Inflammation of the muscle tendon is called tendonitis and may result in pain paired with restriction of movement. Tendonitis of the shoulder typically occurs in the subacromial space and is common due to the anatomy of the shoulder coupled with stressful activity assigned to the joint. The subacromial space is an area on the top the shoulder formed by the coracoacromial arch. This arch is formed by the acromio-clavicular joint, coraco-acromial ligament and acromion (outer edge of the scapula, or shoulder blade).

The chief tendons of the shoulder, the rotator cuff and long head of the biceps, pass under this arch. Reduction of this space exposes the tendons to a high risk for friction, rubbing and irritation, setting the stage for a case of tendonitis. Tendon problems usually emerge in individuals 40 to 60 years old, but are increasingly seen in young athletes as a byproduct of repetitive overuse.


Tendonitis is most often diagnosed as an overuse repetitive strain injury (RSI), but most RSI cases exhibit genetically predisposed factors as well. Individuals that have poor bloody supply to the area are most susceptible to inflammation and development of tendonitis (for example, the supraspinatous). Other high-risk activities or conditions that may lead to the development of shoulder tendonitis include:

  • Participating in activities requiring overhead motions like swimming, tennis, softball and baseball.
  • Repetitive strain injuries (RSI) at work are common in people performing activities habitually in nature such as assembly line work.
  • Sudden injury to the region like a fall on the shoulder.
  • Patients suffering from rheumatoid arthritis may have an increased risk to tendonitis.
  • Aging resulting in changes to tendon elasticity and circulation that increase susceptibility to injury and reduce ability to heal.
  • Postural factors like leaning your head and shoulder forward, reducing the subacromial space, and thus leading to irritation of the shoulder tendons
  • Overload injuries derived from lifting heavy objects or weight training.
  • Weakening of the rotator cuff causing a muscular imbalance resulting in shoulder impingement (pinching).

Signs and Symptoms of Shoulder Tendonitis

  • Pain, either acute or dull, when preforming motion and that lingers even when the shoulder is at rest.
  • In more severe cases, pain that radiates to the upper arm and may be accompanied by a burning sensation restricting movement.
  • Tenderness and/or tightness of the area, especially to one’s touch.
  • Difficulty sleeping on affected side and pain that worsens overnight.
  • Reduction of ability to preform tasks essential to daily life such as difficulty dressing.
  • Increased weakness and swelling of the tendon as inflammation escalates.

Commonly Afflicted Shoulder Tendons

The shoulder muscles that are most frequently impaired are:

  • Supraspinatous: This rotator cuff muscle is commonly afflicted with poor bloody supply at the tendon level and typically involves impingement problems. Commonly an issue for athletes exercising repetitive throwing motions.
  • Infraspinatous and Teres Minor: Rotator cuff muscles that function to turn the arm away from the body (external rotation).
  • Subscapularis:  A rotator cuff muscle with the primary function to turn the arm toward the body.
  • Long head of the Biceps: This muscle is responsible for bending the elbow (flexion), turning the forearm (supination) and assists in raising the arm over the head. Typically, it becomes irritated with repetitive overhead activities and routine lifting during daily activities. Some individuals are predisposed to the weakening of this tendon as they age and may rupture if left untreated.

Treating and Managing Your Pain

At the first sign of tendinitis, one should avoid preforming positions and activities that exacerbate the pain inflicted stemming from the inflammation.

Conservative treatment plans exercised under a doctors care include rest, with alternating application of heat and ice to the area, physical therapy and non-steroidal medications to reduce inflammation. A pain management program may be implemented to help limit discomfort allowing the patient to preform rehabilitation exercises.

If your symptoms persist, steroidal medication or injections may be prescribed by your health care professional to be used in tandem with therapy. Surgical intervention may be discussed to treat highly severe cases to address and correct mechanical causes of the tendon irritation.


If detected and treated early, many patients can recover full function and range of the shoulder provided the patient is dedicated to the treatment program prescribed. Those dealing with a more involved situation such as impingement due to bone spurs, do well with surgical decompression of the area. It is difficult to predict the outcome of tendon tears, as the success of rehabilitation is dependent on the size of the tear, integrity and elasticity of the tissue, patient age, preoperative condition of the patient and if the patient is experiencing any comorbid syndromes. Please refer to the Rotator Cuff Tear section for more information on tendon tears.

Preventing Shoulder Tendinitis

Small measures can be taken by at-risk individuals to help prevent tendinitis – it is far easier to prevent the condition than it is to treat it as some damage may be irreversible or costly to fix. Below list some tips to reduce the risk of tendinitis:

  • Warm-up for any athletic activity gradually. This improves circulation and lubrication to the muscle and tendon. Remember to stretch after preforming strenuous activity as well.
  • Do not bounce when stretching. Instead, hold the stretch for 15 to 20 seconds.
  • Utilize a strength-training program to improve and stabilize the muscles and tendons used for activity. A regular strength-training program three times a week will increase muscle health and help reduce weakening brought on by aging.
  • Always listen to your body – do not work through pain. Avoid the “no pain, no gain” philosophy as you may inflict serious damage to yourself. Pain is the body’s way of notifying you to stop what you are doing.
This page was published on Jul 20, 2017, modified on Oct 18, 2021 by Dr. Freeman (Pain Management Specialist) of Redefine Healthcare
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