What we all need to do as Arnold professes is the mind and muscle connection. While lifting heavy as we need to, we sometimes loose mental focus / connection to the muscle intended to be used. When heavy even if we do not cheat we / me use many different muscles not intended
THIS ^^^^^^
99% of gym users concentrate on moving the chosen weight from A to B.... they fail to remember that the moving of that weight from A to B needs to be done by the muscle that you are intending to train. I've been training with a detached tricep for the last month waiting for my operation date to come - and I have actually gained pec size by taking the tricep out of the workout! I have had to press, fly, cable the resistance purely with my pecs - I have no other option!
With regard to the back, you'll see the majority of guys in the gym rowing and pulling seriously heavy weights for reps.... but if you asked them to hold a peak contraction, they wouldn't be able to without hip or shoulder involvement, and they certainly wouldn't be holding the tension on the muscle being trained.
I have found that stripping pretty much every exercise back to basics with light weights, linking the muscle being trained with the mind, and then overloading progressively week by week, I have made fantastic gains compared to where I was a while back.
Best bit of advice I ever got in the gym was to start every set like a golfer does when preparing to play a shot. He will have the same pre-shot routine every time, making the chances of him messing up less likely.... I set myself, check the selected weight is right, check posture, alignment and then remind myself of the key factors for that particular set - ie: straight back, legs flexed, elbows tucked in etc etc - and I find that doing this, that pretty much every set I do counts.
I've introduced a lot more posing, stretching and flexing between sets to encourage the mind/muscle link to get stronger and I feel I can now control every muscle in my body through thought alone.
Try this for your back.... Step into a doorway and place your forearms on the frame so that your upper arms are parallel to the floor and your forearms point to the ceiling like an old-fashioned pec-dec. Now step forward and you'll obviously feel a nice pec stretch, but hold this position and try to get your mind in tune with your back... can you move your teres major? Can you squeeze your lower traps? Can you tighten your lower lats? All whilst holding this position in the doorframe.
It's only when you get your mind in tune with these muscles and you are able to contract them - that you'll start to be able to target them individually during your workout.
I'll no doubt get some old-school lifters jumping on this and ripping it apart now, but I can only go by the obvious improvements that introducing the mind/muscle link has made to my body - and share it with the group.
Remember: weightlifting and bodybuilding are two totally separate disciplines!
Weightlifting is about moving as much weight as possible for minimal reps.
Bodybuilding is about moving moderate/heavy weight for a preset amount of reps to stimulate hypertrophy in a target muscle group.
You want back size - which makes you a bodybuilder. So you need to train, eat, and use AAS with solely building muscle in mind.
Don't let those goals get lost mid workout!