Encourage your budding athlete to warm up with these exercises (and share them with the coach!). Researchers at the University of North Carolina at Chapel Hill found that doing so can reduce the risk of knee injuries -- especially all-too-common ACL (anterior cruciate ligament) tears.
1. Single-leg balances
Stand with hands on hips and jump forward with right leg, landing with right knee slightly bent and left leg lifted back. Balance on right leg, then repeat with opposite leg. Do two sets of ten reps.
2. Squat jumps
Bend knees and sit butt back into a squat (making sure knees don't jut out over toes); then jump up in the air and rotate the body 180 degrees, landing with knees bent (not locked) and toes pointing forward. Do two sets of ten reps.
3. Sideways shuffle
Start in an athletic stance (knees bent, torso slightly forward, butt back), then shuffle to the right at a brisk pace for about ten yards, with knees bent the entire time and toes pointing forward; reverse direction and shuffle back, leading with left foot. Do three times.