Place both feet on the hack squat plate, hip width apart with your toes just slightly turned out. Lie your back on the machine with your shoulders just under the shoulder pads and a soft bend in your knee. This is your start position. Bracing your core and keeping a neutral spine, bend your knees and lower down into a squat position under your knees are at a 90 degree bend. Inhale as you do so. Pause at the bottom of the movement, then as you exhale, push your feet away from you, extending your knees and engaging your quads and glutes as you do so. Repeat for the required number of reps (or time).