Consider the TLF (thoracolumbar fascia) of the back to be a Grand Central Station of the back, where key muscles attach and actually originate. As we age, our bodies stiffen because fascial tissues harden and contract. Loosening up this Grand Central Station allows wave motion to flow through the back as we walk, move, exercise, play sports. As that rippling wave movement is restored, pain diminishes.
One great way to get the ripple back is the undulating underwater dolphin kick that competitive swimmers use. If you're a swimmer, here's how to practice and improve this impressive water motion: