Sit on a leg extension machine and place your legs under the pad with your feet pointed outward. The pad should rest on your shins just above your feet and you will need to adjust it to suit. Grip the hand bars (if fitted) firmly. This is the start position. Using only your quadriceps, fully extend your legs exhaling as you do so. Hold for a count of one. Return to the start position in a smooth movement as you inhale. Repeat.