A rotator cuff is simply a group of four tendons and muscles that are located right on the shoulder and on top of the humerus bone. (Source 1) The rotator cuff is what controls the shoulder and allows it to move and be mobile. The four main muscles that consist of the tendons are the supraspinatus, infraspinatus, teres minor, and subscapularis muscles. (Source 2). Too much wear and tear on these muscles (such as too many thrown fastballs) is precisely what causes the rotator cuff to begin to tear, as well as swelling in the tendons.
Rotator cuff tears are generally categorized as a chronic injury because it takes repetitive wear and tear on the muscles for it to finally inflict pain on the body. Chronic injuries are simply when the pain gradually continues over a long period of time. On the contrary, acute pain is when something happens suddenly and the pain is much more sharp than compared to the dull and long lasting pain of a chronic injury. (Source 3) In sports the biggest reason why an athlete would tear or injure his/her rotator cuff is not because something major happened instantly like a broken bone or a pulled muscle, but because they continued to put stress on these muscles over a certain period in time. The pain signals will stay active in the nervous system for several months. (Source3) Usually this will occur when the certain activity they are doing is perfomed incorrecty or in a harmful way. An example of this would be lifting too heavy of weights or not using proper technique.
When comparing rotator cuff tears from the common people and athletes, they are much more common when a person is physically active in sports. An injury in the rotator cuff for the common person generally will occur with age. People 40 years and older are at higher risk of tear than younger people. (Source 4) This simply occurs because of the gradual increase of ditiriation over time. With athletes, they use their shoulder muscles over and over again and this can put too much stress on the muscles and tendons that make up the rotator cuff. Sports with an high incidence of rotator cuff injuries include baseball, swimming, tennis, football, volleyball, and water polo. (Source 5) Basically any sport that involves repetitive arm motion. Also, another unfortunate reality to rotator cuff injury is harmful and incorrect mechanics during a specific sport. I have played baseball my entire life, and I have dealt with a numerous amount of teamates who have had shoulder and arm problems simply because they did not have correct mechanics while they were throwing the ball. I know from all of my years of playing ball, that the two main points of stress while throwing a baseball is the later half of the cocking motion, as well as the follow through of the arm. A very easy and effective why from preventing this in all sports is simply using correct form and mechanics, as well as resting and not over using the...