on the topic, height makes no difference for sprints, i know a 16 year old who is 2.02m (ova 6'7) and runs da 1 in 10.61 FAT. Not bad i say. And his main sport is basketball. In our country your not allowed (with the consent of the gym staff/personal trainers) in a weights room til you turn 15 because it is a recognised fact that heavy lifting (as UT posted the girl had done) fuses bones early (school also dosen't allow it for these reasons). The same is appliable to at least some parts of australia as well. Our national education system for gaining credit to enter uni has the physical studies, and one of the main assessments is on the fact on weights fusing bones early and stunting growth, my physios are also the physios of the cheifs, and have done all black physio as well, (this is the sport rugby) and they tell me that lifting too early,ie pre 16+ will stunt your growth, and one of my m8's did a project on weights stunting groowth and passed with honours and their findings were sent to an international sports studies board and performed well there to. Just some reasons why i beleive what i believe, because it's true.
people who say it dosen't stunt growth are almost always being defensive of what they personally did in the past, or more often, what they are making kids do now, and its more for self-reassurance then anything. All people from a neutral angle that i've ever met and discussed the topic with are absolutely convinced it stunts growth (and these are health-professionals to)