I'd like to supplement my lower body weighted work with some mobility pieces. I like Kelly Starret's Squat Series, as well as Kit Laughlin's soleus stretch, but they feature elements of pnf, which I read can damage growth plates in adolescents. Does this danger spread to: 1) the Contract-Relax kind of stretch, where one strives to increase the stretch as much as possible? 2) stretches where one moves in and out of the position, or oscilates through it? Are these safe? I'm fourteen years old, and am around 5 ft 6 in. I can't buy Kit's book as of now, as I am saving money for H1, and eventually, M1. As always, any and all help is appreciated Thanks, Aadil