I am disabled now though as Billy Joel said, "when I wore a younger man's clothes ", I would just slowly walk my hands down a wall until I was able to do a back bend all by myself. I would suggest wearing rubber gloves for the grip. You don't have to train yourself to reach the floor but it did give a nice stretch.
I started doing backbends as a kid so I didn’t really work up to it, but I recommend doing back stretches like cobra pose, if you’re working towards a back bend I would work on strength as well as flexibility. Yoga helps.
No Lia Q.
I do a lot kinds of exercises that need and use the back flexibility and it take me a long time to do a perfect back bend.