To start doing killer crunches you are going to lie back, put your elbows on the floor close to your body. You are going to crunch up and then back down. You are going to do ten of these then you are going to hold the eleventh up. Now while holding that you are going to bring out your legs and feet horizontal to the floor then bring them back down. You are going to do ten of these. And that's how to do our killer crunches to work our lower abs.