For what it's worth, I showed the back exercises in the Pain Free book to my PT today. Interestingly, she thought they were all good for me except the static extension. Said I had too much lumbar curve already, and that that would excarebate it due to the hips moving forward or something and creating too much sway in the back I think. Said I should focus on other thing to combat my arthritis up and down the spine, not to mention my "mild kyphoscoliosis" in the thoracic region (that's from the MRI).
No idea if she's right or wrong about the potential problems of the static extension for me, but I thought I'd mention it. I didn't get the sense that she was the world's greatest expert on the back yet, so who knows?
Also said I was highly flexible/hypermobile and was surprised at how high and easily I could do the basic McKenzie extention. And I was like "Me? Flexible?? That's a first..."
Ah, the mysteries of the back...