Ok so I have years of lifting experience. I am 6'3", 200lbs. My dilemna is that my back (especially the erectors) seem to be disproportionally weaker than the rest of my body. It seems that no matter what I do to target them, the just don't grow. For example: I workout on squats with 3 plates for sets of 10, but deadlifts are hard as hell to do sets of 8 with one plate + 10 on each side.
Part of this may be due to leverage, as I have to really bend over and bring my back into it in order to clear my knees on the way up. So for low back specifically, I have tried deadlifts, roman chair back raises (where your legs are locked in place and you face the floor), good mornings, etc. The other day I tried roman chair raises with no weight since I hadnt messed with them in a while. I did 3 x 15 and my erectors were full of lactic acid/burning after each set. I've done lower rep with some weight added as well, but it doesn't seem to give me results either.
When I took muay thai, we used to do these sort of frog leap things where you would be in a low squat position and hop from the floor to a bench, up and down for about 20 reps or so. I couldn't do more than about 6 or 7 tops. Maybe I need more functional style training like this instead of weight training?