There are NO SECRETS to fitness Leg Scissors are an exercise which can work your Abs and core if you do them properly.  The most important thing is to keep your stomach drawn in. Neutral alignment of you spine should more accurately be described as posterior pelvic rotation. To make this exercise more difficult you can place your hands behind your head. If your back begins to arch, you can bring your feet up higher until you are able to keep your lumbar spine flat on the floor. If you have massive or long legs, this exercise may not be the best choice as it will be difficult not to overload your hip flexors. NOTE: There is no lower abdominal muscle. If you have a protruding lower abdomen you either have excess body fat, or your pelvis is tilted to the anterior which causes your lower stomach to protrude. Personal Trainer Michael Behnken, MS, NASM-CPT-PES, CSCS/best-lower-ab-workout.html