There are many different types of exercises that kids can do to improve their baseball playing skills. The important thing to remember as a parent or coach is to keep the exercises appropriate for the kids' ages, which includes picking activities that kids will enjoy.
One of the best ways for a youth baseball player to improve his arm strength is to throw for distance or to throw items heavier than a baseball.
It's a good idea to have kids throw "long toss" with a baseball every time they are out throwing once they've warmed up. For long toss, they should continue to move farther apart until they can no longer make the throw all the way in the air. Encourage the players to make a nice easy throw, arcing the ball as necessary to be able to get it to go as far as possible.
Another good arm strength exercise is to throw a football that is sized appropriately for the player's age. Throwing a football can also be a fun break in the middle of baseball practice.
Leg strength is an important factor for being able to throw and hit a baseball well. One of the best exercises that young players can do to improve their leg strength is walking lunges. The player steps out with a big stride, allowing the trailing knee to drop down to the ground. He then pushes forward and up to a standing position and strides out with the other leg. Ideally, he should keep his body upright throughout the movement and should not use his hands to push off his legs.
At the beginning of the season, players can start out doing lunges from home plate to first base, working up to going all the way around the bases by the end of the season.
Speed and agility are also important factors in baseball. One of the best ways for kids to build their running speed is by practicing sprinting. At the end of practice, the kids can sprint several different distances: home to first, then first to third; home to second, then second back to home; and home to third.
Another good exercise that is popular with younger kids is to have them form two teams and run a relay race. They can run across the infield from the foul line dirt to the infield dirt and back, tagging the hand of the next player in line, continuing until all players from both teams have run.