Higher rep squats (or DL's, cleans, etc) induce heavy breathing. That is the whole purpose of these style workouts. You are not stretching the chest slightly beyond it's normal ability. But actually, quite a bit with the help of the pullovers (either straight or bent arm). That cartilage, if immature enough/plastic state, between the rib's/breast bone will expand outwards. Mean age is around 24 to 25. before the cartilage forms into hard boney matter. Than it's too late.
No concern of mind if believed or not. We are the masters of our fate when looking for muscle mass and strength. But if anyone would feel a little edgy, invest the time for a high rep, deep breathing set followed by a set of 20 rep deep breathing pullovers right after. See how the chest/breast bone feels in the morning. Just might have been cheating yourself out of a larger and more impressive chest for years. Good Luck.
Side Bar: have used the bent arm pullover with the GVT system for excellent chest improvement. Also including the triceps, lats and Abs.
