I've read in quite a few magazines and also have attended a few lectures in regard to being a personal trainer and so on. I am trying to learn more as I go. But anyway, there is not an upper ab or lower ab, it is one muscle-the rectus abdominus. There are exercises that you can do to work the abs without doing crunches and so on, work circuit training, power your legs like in a jump up in the air contracting the abs at the same time-several reps, remember to always contract your abs in any exercise you do. Interval training is also great. I go to a Cardio Kickboxing twice a week and as long as you keep your abs contracted in all your moves you're working the core. It's all in the core. Now Im learning so people have different opinions, it's just working for me. I don't have 6 pack abs but my definition of my whole stomach area don't look half bad.