This exercise requires a hack-squat machine. Approach the machine, flex your knees, place your back against the padded surface, wedge your shoulders beneath the shoulder pads attached to the machine, and place your feet close together (about 4 inches apart).
1. Inhale, rotate the stop handles on the sides of the shoulder pads to release the machine or sled, and bend your legs.
2. Lower the sled until your legs make a perfect “L” shape and so that your knee does not protrude past your toes.
3. Return to the starting position, exhaling as you complete the movement and perform the next repetition.
Notes: If you do not have a hack-squat machine at your gym, you can replace this exercise with combinations of dumbbell and front squat exercises.
This exercise places primary emphasis on the quadriceps. Adjusting the width of your feet changes the emphasis of muscles worked. For example, if you place your feet close together, you will place more emphasis on the gluteals; if you spread your feet, you will shift the work to the adductors.
To protect your back from injury, be sure to contract your abdominals so that your back remains flat against the pad and so that you avoid swinging your pelvis and spine.