http://www.youtube.com/watch?v=SZDOgHhpp1A
The proper form: Leg press. Choose your weight. Place legs on platform shoulder width stance. Lower safety bars holding the platform. Press and fully extend the platform. Inhale, then slowly lower the platform until your upper and lower legs make a 90-degree angle. Pushing mainly with the heels of your feet and using the quadriceps go back to the starting position as you exhale. Repeat to your recommended sets and repetitions.