Hey, I’m a big believer in olympic lifts and things like that for athletic performance, but my cousin asked me to help him get ready for football, and I started writing up my training program, (I’ve been using a variant of westside with a day set aside for olympic and plyometric stuff) but then wondered if those type of exercises might be too much for a 14 year old to handle, so if you were working with someone 12-14, how far can you go?
I started my little brother on the O-lifts when he was 14. Really just take it slow and be patient, these lifts are a lot for any nervous system to learn correctly.
I did not start lifting weights till I was 22 so I am not talking from experience. BUT:
I would not use plyometrics. I have read that you should be able to squat twice bodywieght before you start plyometrics. More a technique for very advanced athletes.
If I was 14 again this is what I would do:
Start to learn the technique of the olypmic lifts (power versions) and olympic style deadlifts. Keep these pretty light (e.g. 60 - 80% clusters of signals would be good)
Work relatively hard (e.g. 70 - 90% or 3 - 5 reps) on pull ups, hanging leg pikes, military presses, front squats.
Also I would have like to have done a lot of sprinting and maybe swimming.
Also I would have done a lot of bicep curls just for fun because curls get the girls!
I would think the biggest thing in training when you are young is not to overload yourself. If you are using your own body weight or picking a weight up from the ground (if it is too much it does not move) it is hard to overload yourself. In the same vein eccentric only squats and bench presses would not be that good IMHO.