S.B. Hamstring Curl

Start lying flat on floor with heels on top of a stability ball (ball shown in video is 55cm). Next, push heels into ball, and raise hips high. Try to curl the ball toward your hips by pulling heels down the side of it. At the top of the motion, you should have your hips as high as you can bridge. After pausing motion at the top, slowly extend knees and return to starting position.