well for Zerchers are a differnt placement of the bar, the bar rests under the elbows........alot of wrestlers and some pit fighters do these.....IMO ~~~~NO~~~~ need to do these for olympic lifters, bodybuilders, and powerlifters.......really no need unless u are trying to improve balance bro just go lite on sqauts and IMPROVE YOUR FORM .,.......if sqaut done right it shoundnt hurt the back and knees....