Place one foot on the hack squat plate, with the other leg resting. 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 knee 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 foot away from you, extending your knee and engaging your quad and glute as you do so. Repeat for the required number of reps (or time) and then alternate legs.