I've just hurt my back and I wanted to start working out again. I don't want to put much stress on it again and I was wondering what type of ab exercises are bad for the spine so i can avoid them. Also what types of ab exercises are good for people with a bad back?

What are the most effective ab exercises for your lower abs? What are the best/ most effective lower ab exercises?

What are the best ab exercises to do help get a flat stomach?

I injured my lower back at work, but I still want to do ab exercises. Anybody know of any that don't put very much pressure on the lower back? (Basically anything I won't have to get down on the ground and curve my back to do) Any suggestions welcomed and appreciated.