Deciever: Imagine you are pushing your whole upper body into the bench. You sort of have whole body tension.....like a realy firm base from which to press off
SAGAT: a squat rack is a gift from the gods. I take it you train at home? I have trained the last year with out one(at home with no spotter).......and never noticed its importance till i started powerlifting. i now own one......and it has changed the way i train. Yes you have a disadvantage with no spoter as well.
i feel i cant go "all out" with out one or the other. The speed day is fine its just the max effort stuff.......sometimes you dont quite make it. so you are going to have to change something.......go to a gym/different gym, train with someone, invest in a powerrack or even make one.
now for the lower back: shit. I dont know how to deal with lowerback problems. I have found my back getting stronger training this way.......but i had an okay back to begin with.
have you had your back checked out?