Begin this exercise by lying on the floor or a flat bench. Knees and hips bent.
Flex your waist to raise your torso from floor on bench. Keeping your lower back flat, raise your torso up as high as possible contracting your abdominal muscles. Hold for a second and release. Lower your torso back down until your shoulders make contact with floor or bench.
Note: To make the exercise much more challenging add weight or another form of resistance.