SpikeyLizard, I dont see how the mechanics of the lift will vary between a big O-lineman and myself. He may weigh more than me but that doesnt change the mechanics of the squat. Unless what you are saying is that if I go heavy stay at parallel but for the lighter reps I should go below parallel. The other fact that puzzles me is if there is so much shear force excerted on the knee at parallel then arent you excerting that force to the knee twice every time you squat below parallel, once on the way down and once on the way up? Seems like twice the amount of wear and tear on the knee for the one lift. What really concerns me about going deep with heavy weights is the strain on the knee at the bottom. I have watched some guys hit the bottom of a deep squat with alot of weight on and actually try to bounce out of the hole. Now I know that isn't good for the knee, and I guess I can totally avoid that sutuation by not going deep with the heavy sets.
