Throwing Sports and the Shoulder
Throwing relies on repetitive movements that require a high level of precision. To prevent injury and create the highest level of performance there must be appropriate biomechanics of the shoulder girdle and the muscles that move it. Precise biomechanics must also take place in the muscles of the back, hips, knees, ankles, and feet as these all create the stability on which the shoulder moves.
Pitching and throwing mechanics lead 80% of baseball players to an Internal Glenoid Impingement. This is experienced as pain in the shoulder, usually with overhead movements. The impingement starts out from inflammation in one or more tissues in the area and usually leads to a chronic inflammatory response in multiple tissues in the area. This leads to fibrosis and tendinosis that further degrade the function of the shoulder. If the athlete begins anti-inflammatories and pushes through these pains game after game, they are setting themselves up for a short career.
If you start to experience one or more of the following: muscle weakness in the rotator cuff muscles, over rotation of the shoulder while throwing, hyperangulation in the shoulder or elbow while throwing, and scapular dyskinesis (improper movement of the scapula), then you are on your way to a shoulder injury. These all lead to microtrauma in the shoulder tissues which set off internal impingement. If the appropriate treatments are not implemented, rotator cuff tears, SLAP lesions, posterior capsule contracture and a host of other injuries usually follow. This creates instability, which can lead to dislocations on top of the existing shoulder pains.
The best approach is to learn proper throwing mechanics as soon as possible and practice these mechanics until every throw puts the least amount of strain on the shoulder. Only a small number of coaches teach these proper mechanics. If you can, try finding a doctor who has studied these things and can show you proper mechanics through the five stages of throwing; wind-up, early cocking, late cocking, acceleration, follow-through. Next is a training program that reinforces proper throwing mechanics. See a doctor who can perform manual muscle testing on the muscles of the shoulder to determine an appropriate and individualized training program for you, focused on functional mechanics (as opposed to isolated muscle contractions).