REVERSE CRUNCH PULSE
Begin lying on your back with your legs up in the air, perpendicular to the floor. Keep your arms down along your side with your palms facing down. Squeeze your lower abs and raise your butt and lower back off the floor with quick pulses. Try not to rely on momentum, but focus on only using your lower abs. You can do it either with legs straight up or legs bent at the knees with shins parallel to the floor.