To begin, place a flat bench 2-3 feet behind the smith machine. Then, set the bar on the height that best matches your height. Once the correct height is chosen and the bar is loaded, step under the bar and place the back of your shoulders (slightly below the neck) across it.
Hold on to the bar using both arms at each side (palms facing forward), unlock it and lift it off the rack by first pushing with your legs and at the same time straightening your torso.
Position your legs by placing one foot slightly forward under the bar and extending your other leg back and place the top of your foot on the bench. This will be your starting position
Begin to slowly lower the bar by bending the knee as you maintain a straight posture with the head up. Continue down until the angle between the upper leg and the calf becomes slightly less than 90-degrees (which is the point in which the upper legs are below parallel to the floor). Inhale as you perform this portion of the movement. Tip: If you performed the exercise correctly, the front of the knee should make an imaginary straight line with the toes that is perpendicular to the front. If your knee is past that imaginary line (if it is past your toes) then you are placing undue stress on the knee and the exercise has been performed incorrectly.
Begin to raise the bar as you exhale by pushing the floor with the heel of your foot mainly as you straighten your leg again and go back to the starting position.