i do cable rows...like i was taught...."like your rowing a boat". so ill pull forward and ill pull all the way back...see guys keep there back strait and use all biceps to pull the weight...the point of that exercise to work your back not your bis..thats why they are called rows
Having your back straight turns a cable row into a bicep exercise? That's not correct at all.
Only way you would turn that into a bicep exercise or even increase biceps to involvement, would be if your back was rounded, thus preventing the back muscles, (the rhomboids in particular, which are the prime movers in a rowing movement. Not the last, as most people believe).
Actually, by leaning back into the movement like your rowing a boat, you're actually shortening the range of motion and recruiting less fibers in your back