My lower back always use to be my achilles heel. Before I started into powerlifting I use to have my back go out every 3 months or so and it would take 1 - 3 weeks to get it feeling good again. Even the chiropractor could not work the impingement out all that well. Once I started powerlifting I tried a number of exercises to strengthen the lower back and the posterior chain and the one I found helped the most and increased my squat significantly was bent leg good mornings with a straight bar, cambered bar and smith machine. Keeping my back straight and my chest and head up, pushing my ass back as far as I could would result in bending at the knees and my chest moving downward putting a lot of stress on the lower back glutes and hamstrings. Once I got down as far as possible and safe(back not rounding) I would push up on the bar with my traps and thrust my hips forward. I use to do these a lot. Never had a back impingement for years once I started doing these. Once I stopped doing them that was another matter. The best set I have done with these going fairly far back with the ass was 3 reps with 455. I use to work up for a work set 2 -3 with a bit over 400 most times when I used them in my routine... enjoyed doing this exercise,,, always have.
