How to do the Leg Extension

Sit on the machine and adjust the seat so your knees align with the pivot point.
Place your shins behind the lower roller and grip the handles securely.
Extend your knees until they are nearly straight, feeling the muscles in front of your thighs.
Slowly lower the weight back to the starting position.

Full technique — 6 steps

Adjust the seat so your knees line up with the machine's pivot point.
Sit back against the pad and place your shins behind the lower roller.
Grip the handles and start with knees bent comfortably under the pad.
Extend your knees until your legs are nearly straight and quads fully shortened.
Squeeze the quadriceps briefly at the top without kicking or snapping the weight up.
Lower the pad back down until your knees are bent and the weight stack stays under control.