Childrens Track

Question
I have a 12 year old son.  He's a little on the small side; only weights about 79 lbs.  He wants to join Track next year at school and wants ankle weights to put on his legs now so he can start practice jogging with the weights on.  Will that harm him in any way, with his legs not being fully grown yet or very strong?  He's starting with 2.5 lbs. on each leg.

Answer
Yes, it will definitely do harm to him. Firstly, as you point out, he's 12. His body is still growing. Running and making sure he gets adequate rest is one thing, but wearing ankle weights is another. It tears up his legs unnessicarily.
I wouldn't reccomend (nor would any other half brained running mentor) ANYONE using ankle weights. Running is a bodyweight feat. The purpose of running is to train muscular endurance into your muscles. If you run with weights, despite the common ammeture notion, you won't be faster or have more endurance when you take them off. Running with weights does not train the quickness in stride and the muscular endurance type needed to run a race into your muscles. It only builds your leg muscles. Does this mean he's going to do better with big leg muscles? No, becuase his muscles are going to be trained for weightlifting, not running. Tell me about ONE professional track athelete who trains with ankle weights, and I'll say I'm wrong (not really, I'd actually call him an idiot)
I'm only saying all this to sum up the answer, I just think it's a horible misconception, ankle weights.
Jared