Follow machine instructions for set up and select desired weight. Sit so that foot pad is behind the ankles, thighs are flush with the seat (but backs of knees are off of the seat), and thigh pad (if present) is just below the knees. Keep knees above ankles, back straight (and flush against pad behind you), abs engaged, and hands lightly gripping handles at your sides.
EXHALE: Slowly bend at the knees to "curl" your heels down towards your buttocks.
INHALE: Slowly straighten knees to return to the start position to complete one rep.
This can be a very dangerous exercise for the knee joint. SparkPeople recommends that you practice extreme caution when doing this move, using a light weight, or avoid it entirely.
Muscles Worked: Hamstrings