Heavy brother....lower reps, heavy weight, get a full stretch and then pull all the way to your chest and really squeeze and pause for a couple seconds really feeling that burn and repeat. Nice and controlled. Every couple weeks switch it up and do a week of faster pulls in and out with slightly lower weight till exhaustion each set to ignite those faster twitch muscles. Just keep tricking your muscle changing it up. Dumbbell reverse flies on a 45° bench to really maximize that upper center of the back. Personally I prefer a gainer with a banana, two scoops of peanut butter and a shot of honey 45 min beforehand on days I'm working large muscles like the back, legs, etc.... and then soon as I get home a whole can of tuna between two slices wheat bread lol. That's my feed and grow routine for heavy lift days. Everyone's got their thing, but this works amazing for growth for me.