Whether you're throwing out base runners from the confines of Fenway Park or turning a 6-4-3 double play on a local Little League field, throwing is one of the most important, and physically demanding, aspects of baseball
Just as major leaguers can get a dead arm during spring training, younger players also risk injury as they begin throwing regimens in the spring. The Seven Ball Drill below is a great way to increase arm strength and prepare players for the various throws they will make during the season.
Note: Perform the drill's seven separate steps in sequence to ensure proper arm development.

Baseball Arm Strength Drill
    Stand shoulder- width apart, with throwing arm placed upwards at a 90- degree angle. While holding elbow with glove, throw ball to partner using just the wrist.
    Sit with legs spread and arm in same position as exercise above. This time use the area from the elbow up to throw ball to partner.

    Remain sitting and throw ball by rotating hips and turning upper torso. (Focusing on follow- through is not necessary.) Use the glove arm or elbow to direct throw.
    Go to one knee. Throw ball by rotating hips and turning upper torso, as in above exercise. This time emphasize follow- through across the raised knee.
    Stand with glove arm closest to partner, and feet shoulder- width apart. Repeat the above steps, concentrating on follow- through. This time throw without moving your feet.
    Use all the steps above, this time add a crow hop and throw ball to partner. (Crow Hop: A technique in which you hop forward on your front foot during the wind up of your throw.)
    Long toss is the last step. Stand approximately 10 feet apart and toss the ball to partner as quickly as you can for one minute. You can even keep track of the number of catches to turn this into a competition. Emphasize a quick release and concentrate on the ball entering and leaving the glove. Note: For infielders, you can turn this last step into a quick toss by reducing the distance.
By following the steps above, players will find it easier to make all the necessary throws in a game, as well as keep their arm healthy throughout an entire season. A good goal to have, no matter the league, when opening day rolls around.