http://www.youtube.com/watch?v=gw0KQLkf7e4
The proper form: Leg curls. Adjust the machine lever to fit your height and lie face down on the leg curl machine with the pad of the lever on the back of your legs. Keeping the torso flat on the bench, ensure your legs are fully stretched and grab the side handles of the machine. As you exhale, curl your legs up as far as possible without lifting the upper legs from the pad. As you inhale, bring the legs back to the initial position. Repeat for the recommended amount of repetitions.
