This is a very debated subject and I have been doing some research on this and have found conflicting information. Seems old school thought was that resistance programs could close growth plates prematurely in young kids. New school thinking debated that and states it may be safe when done properly.
Lots of info on the internet about this. try this site and go to the bottom of the page and do a search for growth plates.
www.niams.nih.gov
Anyway I have found information stating that it is safe when done with a good trainer who knows what he is doing (most of us qualify). I read somewhere that compound movements such as deads and squats are not as safe as some other exercises like bench, leg extension etc..
Anyway let me know what you think.
My son is 7 years old. He is in competitive gymnastics and they have him practicing 5 hours a week. half that time is spent doing pushups, situps, L Hangs, rope climbs, pullups, hand stands etc. The other half is spent doing the rings, floor routine, P Bars, High Bar etc....
I also work him out at home a couple times a week doing pushups, situps etc. no squats or deads. When you think about it, light weight high rep work is easier on the body than pullups and pushups. I have not started my son on weights yet until I learn more but i have thought about starting him on a high rep routine on my old Bowflex that is collecting layers of dust. That would be perfect for a kid I believe because there is no momentum involved and it is safer than freeweights.
More thought? Any docs around?