Lie on your back on a decline bench and hold on to the top of the bench with both hands. Don't let your body slip down from this position.
Hold your legs parallel to the floor using your abs to hold them there while keeping your knees and feet together. Tip: Your legs should be fully extended with a slight bend on the knee. This will be your starting position.
While exhaling, move your legs towards the torso as you roll your pelvis backwards and you raise your hips off the bench. At the end of this movement your knees will be touching your chest.
Hold the contraction for a second and move your legs back to the starting position while inhaling.
Repeat for the recommended amount of repetitions.
Variations: You can do the movement on a flat surface and as you get more advanced you can use ankle weights.