when throwing a baseball overhand the muscles you use are
deltoids.
triceps.
latissimus dorsi.
abdominal muscles.
hips.
glutes.
so you should stretch and make sure you dont pull or hurt these muscles but you dont have to throw overhand Pitching underhand wasn't a gimmick for Gheen, it was his preferred style. He was mentioned in newspapers across the country for his unorthodox technique. An MLB umpire confirmed pitching underhand is allowed. also a good exercise to work out your arm would be A baseball push-up is meant to increase the power of your arms and core, and to increase the coordination between the two. This exercise also promotes good posture because it forces you to flex the muscles of the core in order to keep the lower back from bending.
and i'll leve you with a quick fact: Softball pitchers use an underhand motion that is not as stressful to the shoulder joint as the overhand pitch used in baseball. Softball pitchers can often pitch several games in one day, and often have an extended career of many years due to the lower stress levels on the shoulder joint.
