I decided to start teaching yoga following a series of car accidents and attendance on a back re-habilitation course at the Nuffield Hospital in Oxford to help people with back problems. This involved a lecture 10 weeks in the gym and 10 weeks in hydrotherapy and some 6 months later having persevered with the exercise regime I was back to normal.
You need to strengthen the core muscles and those supporting the back to keep mobile and the pain at bay. I do not have any current back issues. Pranayama (yogic breathing) is good for the back as it uses many of the muscles that also support the back. There are of course specific asanas such as the “cat” which are good for the back and I have some notes from specialist courses available.