THE perfect ab exercise is the Plank Pose. When you do this exercise you are training your abs to pull in and stay in. We all know that you look alot better when you pull your stomach in. This just trains the muscles to stay in.
If you haven't done a plank before, start on your knees (like a girl push-up position) and hold for about 30 seconds. Progress to 60 seconds before you move to the stardard pose. Standard Plank Pose is like you are starting a push-up on your toes and hands but just keep your arms straight. Make sure your body makes a straight plane (don't let your back sway down or arch up). Hold for 30-60 seconds. Think of pulling your stomach in the whole time. This will help support your back.
You can also do this kind of plank like Arabella. You place a stability ball under your legs and hold your plank that way. This is my favorite kind of plank because it works more of your stability muscles in your core. More bang for your buck. : )
The Plank is also so wonderful because it helps hold your organs in the right place. When you have that nice strong core, you keep from everything pushing down on your bladder. And we all know what happens when our bladder is weak. NOT good!