This exercise is used to build the muscles of the upper leg which include the quadriceps, hamstrings, and glutes. This exercise is similar to a squat, but performed on a machine.
Begin by placing your shoulders under the designated pads and force your back against the pad. Place your feet onto the bottom platform, high up on the platform so your knees to go in front of your toes. Your feet should be approximately shoulder width apart with your toes pointed slightly outward; find where you feel most comfortable, your stance can vary in width. Now grab the arm handles, which are usually in front of the shoulder pads. Push off the platform with your legs, and then turn the handles in towards your body; this will release the weight and you are ready to begin. Squat down, while keeping your head and your back pushed against the back pad firmly. Continue to squat down until your hips break the plane of your knees, your upper thigh will be parallel to the floor or machine platform. Once you reach the bottom position, push through your heels and straighten your legs until you return to the starting position. Repeat for a set number of repetitions.
Make sure to hit your depth on this machine, the hack squats provides a great range of motion than other squat machines.
There are many different machines that perform a hack squat, make sure to read the directions on the machine and perform it correctly.