A great exercise for the back of the thighs and the buttocks.
- Lie on your back on an exercise mat. Place your feet on the top of the exercise ball and have your arms on the floor beside you. Lift your buttocks off the floor a few inches.
- Press your heels down into the ball, then exhale and bend your knees, pulling the ball in towards your body without letting your hips drop down. Inhale and slowly extend your knees to return to the start position.