The article mentions that viniyoga was the style used. It is a therapeutic yoga specifically targeted to issues like low back and quite often adapted to individuals instead of in a group format, so it’s not like a regular yoga class. I have several viniyoga videos by Gary Kraftsow and they are excellent. He teaches a specific sequence of yoga postures, and when done regularly, I found they do help relieve low back pain. As a certified yoga teacher, I’ve also incorporated them into my classes, which were largely middle-aged people who tend to have these types of issues (like me!)
You can probably find the videos at your local library. Ours had them but I purchased the DVDs so I could use them whenever I wanted.