Seated Leg Extension Machine 

Starting Position 
Follow machine instructions for set up and select desired weight. Sit so that food pad is just above the ankles, thighs are flush with the seat (but backs of knees are off of the seat), and back is straight and supported by pad. Keep knees above ankles, back straight, abs engaged, and hands lightly gripping handles at your sides. 

Action 
EXHALE: Slowly straighten your knees to push the leg pad upward. 

INHALE: Slowly bend at the knees to return to the start position to complete one rep. 

Special Instructions 
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 (that you can lift for 18 repetitions), or avoid it entirely. Another safe alternative is to lift the weight only halfway vs. straightening the legs.  

Muscles Worked: Quads