First choose your weight and sit on the machine with your legs under the pad (feet pointed forward) and the hands holding the side bars. This will be your starting position.
Using your quadriceps, extend your legs to the maximum as you exhale. Ensure that the rest of the body remains stationary on the seat. Pause a second on the contracted position.
Slowly lower the weight back to the original position as you inhale, ensuring that you do not go past the 90-degree angle limit.