Laying on the ground on your back place one leg on the ball. Make sure that the bottom of your calf is the part of the legs that is supporting most of your weight. Place your arms out to the side of you to help keep your balance. Elevate your hips and lift your back up off of the ground. Slowly bring your feet to your buttocks and raise your torso up as you do this. Squeeze the back of your legs (Hamstrings) and slowly return to the extended position you see in the image. This exercise is typically SUPER SETTED with another leg exercise!