The tendons in the shoulder slide through a very narrow passageway and attach to the shoulder bone. Impingement occurs when the space between the bones in this passageway is reduced. This can occur from repetitively moving the shoulder into a stressful or suboptimal position. When this occurs, the bones
in the shoulder pinch down on the tendons and cause shoulder impingement. You should be aware of the dangerous movements that can lead to shoulder impingement. These movements include hanging on your arms during rest stances, climbing with a hunched posture and strenuous overhead reaching.