Reverse Crunches

Lie on the floor on your back with the palms of your hands flat on the floor at your sides. Bend your legs to 90 degrees and bring your legs up so that your thighs are perpendicular to the floor.

Using your abdominal muscles, curl your knees toward you chest until your buttocks lifts off the floor and then slowly return to the starting position.

The entire motion should be done in a smooth, controlled manner that lasts about 3 seconds, with the downward movement no faster than the upward.