Sit down on the machine and place both legs behind the bottom brace pads. Keep your back straight and head up as if looking into the horizon. This is your starting position.
Lift the weight up with ONE leg all the way until your it's almost straight but remember not to lock-out your knee. You should always keep tension in your leg(s) for maximum movement efficiency. Then, lower the weight back down to the starting position but don't allow the weight plates to bang into each other; always stop short of this happening.
Finally, repeat the entire movement for the desired or prescribed number of repetitions and then switch and do the same with the other leg.
Perform this exercise in a smooth and fluid motion
Don't extended your leg(s) completely at the top portion of the movement
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or increase the weight.