This is a tube workout. Standing on one end of the tube, you hold the other end and abduct your arm to at least shoulder height. This is a good workout to strengthen your shoulder and rotator cuffs. The rotator cuffs are often the cause of serious injuries to many pitchers. Strengthening them is important to allow the muscles and tendons to undergo such stress during pitching.
Another rotator cuff exercises, working your posterior deltoids. Bending at waist, arms hanging down freely. Squeeze shoulder blades together and bring weight straight out to shoulder height. Return to start position in a slow, controlled manner. This also works your trapezius muscle, which undergoes stress during pitching and can be easily torn if not stretched and strengthened properly.
Wrist curls. Sit on an physioball ball, or bench so that your knees are bent at a 90-degree angle and your feet are flat on the floor. Secure a circular piece of elastic tubing underneath the ball of your foot and hold the other end in the palm of your hand. With your palm facing the ceiling and your forearm flat against your thigh, curl your wrist up and down. This strengthens the forearm, wrist, and elbow. Each of the parts is important to be strong in the prevention of injuries when throwing and pitching a baseball.
It is also important to have a strong core to help keep balance. These muscles link the lower body to the upper body and throwing arm. A pitcher also gets a great deal of his power from the coiling motion of the core.