I have very poor abdominal strength - the muscles seem nonexistent. I've never seriously dedicated myself to making them stronger. I'm starting to work on my abs now - what is the best way to build them up? Normal bodyweight ab exercises, or weighted exercises?
Learn to incorporate compound lifts into your routine, these will build abdominal strength (albiet indirectly) relatively quickly. You can worry about isolated movements at a later time. If you want your abs to show "the 6 pack" you're going to have to drop your bodyfat.
When I say compound I mean deadlift, squat, overhead press, pull/chin ups, dips, barbell row, bench press
USF, you hit the nail on the head - nothing builds abs like squats, deads and overhead presses! They get the bulk of the work done and then you can isolate them with some of the other movements suggested in this thread after you have gotten stronger. But compound movements will elicit the biggest effect overall.
I know compound lifts are the best way, but I have scoliosis and virtually no abs to support me, so when I do squats and stuff my back kills me. Even at a low weight, I just can't support myself correctly.
Trying doing the 'plank' with just your bodyweight and hold it as long as you can. Once you can hold it for around 2 minutes, add some weight on your back. Hold that as long as you can. Once you can do that weight for around 2 minutes, add some more weight. Gradually of course, and I'm talking about doing this like once a week...I have very poor abdominal strength - the muscles seem nonexistent. I've never seriously dedicated myself to making them stronger. I'm starting to work on my abs now - what is the best way to build them up? Normal bodyweight ab exercises, or weighted exercises?
Oh, that does throw a wrench into the works. Have you looked into braces/belts?
I agree cable crunches may be your best option
Make sure to give them proper rest as well since they are a muscle group and need time to recover from the work you put on them.
How much rest? I've heard people say work them once a week and people who say do it every day.
How much rest? I've heard people say work them once a week and people who say do it every day.