I know what you mean with back trouble. But if you can do leg lifts and start getting your abs worked a little that will help to get your back strong again.

I had lower back surgery in 1998 for a hurniated and ruptured disks. 8 weeks after surgery I was cleared to go back to Curves for women and didnt have any problems with the machines hurting my back at all.

Now that I am nearly 4 1/2 years post op I need to get my abs back in shape because I have been neglecting them and my back hurts because of it.

Good luck