This is a good video explaining the disorder of rotator cuff impingement. Strictly speaking, I would exchange the term ‘tendinopathy’ for ‘tendinitis’. There is a clear explanation of one of the common circumstances that lead to this problem, where the muscle tendon is vulnerable to a pinching stress under the roof of the acromion process and collar bone.  The benefits of both conservative (non surgical) and surgical treatment options are discussed and demonstrated.