Good question!

I'm not entirely sure, but here is my educated guess.

The biggest change was that I spent a lot of time vetting each exercise for my specific injury points and asking whether this was really the best way to work that muscle group. I ended up replacing 60% of the workout with new exercises that allow me to lift more weight or target different muscle groups, while taking pressure off those injury points.

I think I had grown to use more weight with a few exercises that, on paper, shouldn't cause a problem, but were causing more stress on my injury and the supporting muscles. I found ways to isolate those muscles without putting as much tension on that area. I also added more core-strength exercises, including some for the hip flexors, which might be helping support as well. I was likely doing planks for too long, and switched to hardstyle, etc.

Last year, I was pain-free 90% of the year, and most years I run around 95% to 98%. Last year just felt different, and the rehab wasn't working the way it was. Since switching to this workout about 8 weeks ago I've been 100% pain free in a way that is hard to describe. My back has just felt light and happy, I can jump up on boxes and back down with no worries.

This is on the back of 10 years of rehab, 10 years of education, 10 years of learning about my injury and body, etc. AI is not some magic button to all the people who might jump on this thread :), it's a tool, and I want to stress that. But I've tried to do this in years past, and I couldn't do it. This was a game-changer. I tred with ChatGPT3 and it was useless at the time as well.