People who have a shoulder problem feel strong pain when they move their arm especially from 60 degrees to 120 degrees abduction (lifting the arm up to the side above your head). There are various causes of this condition. For example, rotator cuff tear, peri-arthritis (general shoulder pain for ages 40-50), and shoulder bursitis. Interestingly, pain is relieved over 120 degrees. Simply explained, it is due to the structure of the shoulder.
Dr. Noguchi, orthopedic surgeon, Japan