It's those oh so difficult hinge rows!!
I've been doing them for months now! It's starting to feel and look way smoother and I think ROM has improved too. Only thing is....damn burning of the forearms and biceps. This was my first set of 8 so no fatigue. But wow, near the last few sets they burn so bad (not in an injury way, just super pumped)
I can actually manage 15 in one set, but it ruins the next 3-4 sets, so had to step back and keep it consistent.