dr. david altcheck knows all about baseball injuries. he's the medical director for the new york mets. with the help of a young pro named rob semerano, the doctor is helping kids learn how to protect themselves and their future. >> don't throw a baseball as hard as you can while you're still growing. don't throw it when you're really tired, and listen to rob and learn how to throw it correctly. >> ...so all my energy is going in one direction. bring that knee up, step, and throw. all one motion. there we go. much better. i think one of the most common mistakes that young players make is throwing all arm, so to speak. they don't use the big muscles in their legs to help generate the energy and transfer it up to their upper body to their arm, idand it puts too much wear and tear on the elbow and shoulder joints. >> the safe kids u.s.a. program teaches that a healthy pitching career takes more than power ann precision. >> one, two, three... >> it takes an overall commitment to the health of your body, from learning the right way to warm up and stretch to knowing what's in your favorite fo