Lay flat on a bench or platform. Press your back firmly against the surface. Hold on lightly to stabilize yourself, but try not to use your hands to support your leg raise. Flex your hips, keeping your legs straight. Lower them just enough to provide tension on your abdominals.
Slowly lower your legs, keeping your back flat, to the point where your trunk is challenged to hold your back in its original position. Hold, continue to contract your abdominals and hip flexors. Slowly lower your legs to their starting position while pressing your lower back against the surface. To increase resistance and stretch your calves, pull your toes back as far as you can.