is it better to do stiff leg or bend at the knee when doing deadlifts.? which version builds the hamstrings better.? also i read somewhere that the biggest mistake people make when doing lying hamstring curls is using too much weight. what is your opinion/advice on that issue.? also, when an older guy like myself reaches the point where you have obtained the the heaviest one rep max that you want and don't want to go any heavier how do you adjust to the 80% rule .? you don't want to continue to use the same weight all the time right.?

i think stiff legged deads build the hammies better, because its lengthening it