The shoulder blades are the foundation of the shoulder. If the muscles around the shoulder blades get weak, it will not take much to cause an injury when doing repetitive movements especially overhead movements. Not taking the necessary breaks while making repetitive movements can lead to added stress on the shoulder and cause painful injuries.
Make sure you strengthen your shoulder muscles to avoid injury. When most people exercise, they don’t think to do shoulder specific exercises. They feel that they are strong because they do bench press or squats. However, if they are not doing Rotator Cuff specific exercises, then they are not properly strengthening the shoulder. It is important to properly ice and control inflammation after strenuous activity, if not the uncontrolled inflammation can weaken tendons and muscles eventually making your shoulder vulnerable to injury.
These are the main causes of shoulder pain.