Shoulder tendonitis is a condition caused by inflammation of the rotator cuff and/or biceps tendons (the structures connecting muscles to their adjacent bones). This is usually the result of the tendon being pinched by adjacent structures and can occur in sports that require the arm to be moved repeatedly above head height e.g. weightlifting, racket sports, baseball or even certain swimming strokes. Pain and tenderness in the shoulder, as well as an inability to hold the arm in certain positions, are the typical symptoms. A shoulder support or arm sling can help to restrict the movement of the shoulder structures and give the injured tendons a chance to rest and heal properly.