How to do the Hack Squat (Machine)

Position your shoulders under the pads and place your back firmly against the support.
Stand with your feet shoulder-width apart on the machine's platform.
Release the safeties and bend your knees and hips downward in a controlled motion.
Press through your whole foot to stand back up, keeping your back against the pads.

Full technique — 8 steps

Set your shoulders under the pads, place your back against the support, and plant feet on the platform.
Position your feet around shoulder width with toes slightly turned out if that matches your hip mechanics.
Release the safeties and stand tall with a slight knee bend, not fully extended.
Tighten your stomach and keep your hips and shoulders in contact with the pad.
Lower by bending your knees and hips until your thighs reach your deepest controlled position.
Keep your whole foot pressed into the platform and your knees pointing the same way as your feet.
Drive the platform away by extending your knees and hips to return to the top.
Stop just short of full knee extension before starting the next rep.