I have an injured lower back (not diagnosed) that doesn't really bother me unless I try to squat/DL heavy. I have no pain whatsoever in my normal routines. The question is, is it possible to keep gaining quad size with lowish weights? Previously (like 3 months ago) I was repping front squats with 315 but now cannot go over 225 (and even that begins to hurt) as it really aggravates something in my LB and I don't want to risk it. I've found that I can do hack squats pain free. thanks to the back support, even if I go heavy and also use pre-exhaustion methods before doing squats. Like heavy leg extensions first and then squats. This way I don't have to squat big numbers (for me anyways), remain pain free and still get a good workout. Can I still grow well using pre-exhaustion methods (and heavy hacks from time to time) or are heavy weight squats mandatory? That's what I was doing until getting injured but...not much I can do now. BTW, I have tried taking 2 week breaks from leg training etc. and then squatting heavy again. It still hurts.