This exercise uses a ball to isolate and work the lower abdominal muscles.
- Lay down as if you were performing a pushup.
- Place your feet and shins over an exercise or stability ball.
- Keeping your back straight and supporting your weight on your hands, pull your knees towards your chest, so the ball rolls forward under your ankles.
- Crunch your abs and then roll the ball back to starting position straighten your legs.
- Keep your back straight as you perform this exercise.