The machine-assisted pull-up takes a classic back-building exercise and adds assistance to make the movement easier than the bodyweight version. The amount of assistance can easily be changed by moving the pin in the stack. While some people use this variation as a substitute for pull-ups or as an assistance exercise for pull-ups, it is also effective as a way to perform the pull-up motion in traditional muscle-building ranges. This variation is often performed for moderate to high reps, such as 8-12 reps per set or more, as part of upper-body or back-focused training.