Set up the hack machine by loading the weight you want to use.
Position yourself with your chest flat on the pad and shoulders up against the shoulder pads.
Position your feet at around shoulder width apart on the bottom of the platform.
Push up to take the weight off the stack, place your arms on the side handles of the machine and disengage the safety bars. This is the starting position for the movement.
Slowly lower the weight down until your thighs are at approximately right angles with your calves.
Pause, and then push the weight back up to the starting position without locking your knees at the top of the movement.
Repeat for desired reps.