Purpose
of exercise: TO TRAIN
THE SHOULDERS.
Doing
presses on a machine helps you to do the movements very strictly, and allows
you to avoid clearing a weight if you to avoid cleaning a weight if you have
some sort of physical problem. Also, you can let the weight come down much
lower, which gives you extra stretch in
your front delts. There are any numbers of machines on which you can do
a shoulder press movement (Universal, nautilus, smith) but the principle
remains the same.