Exercise Ball Hamstring Curl

Setup
Lie supine with heels on the exercise ball, knees and hips straight. Place arms at sides to support.
Movement Instructions
Roll the ball in, bending knees and rolling so soles of the feet are on the ball into a hip bridge. Extend knees and roll the ball back out so heels are on ball and hips and knees are straight. Repeat.
Comments
Keep a straight line between shoulders, hips and knees at top of movement and keep hips straight throughout.