The Hack Squat, (or Hack Lift, as it is sometimes called) is a behind-the-back deadlift, as demonstrated by famous oldtime physique star Walter Donald in the pages of Super Strength by Alan Calvert.
This movement is not actually named after George Hackenschmidt but gets its name from “Hacke” the German word for ankle, which is roughly where the bar touches before the commencement of the lift. One coaching point on this lift which is not obvious is that the hands are supposed to be touching. Several lifters have been able to perform this movement with nearly 800 pounds.