Lie on the floor with your feet on a bench and your legs bent at an approximately 90 degree angle. Place your hands at your temples or cross your arms over your chest. Raise your head and shoulders toward your knees with a situp motion and simultaneously lift the pelvis. Feel the lower and upper abs contract together. Flex the abs hard at the top of the movement to get maximum contraction. Avoid pulling on your head with your hands. It may help to exhale just before crunching upwards.
Here are a few suggested alternative exercises:Ab CrunchAb Crunch ObliquesBall Crunch TraditionalDouble CrunchDumbbell Side BendsLateral Bend with Barbell