Since self-improvement is a major TRP goal....

I was a gymnast for ten years. My knees and back are shit. I eventually blew a disc in my back, ultimately had a spinal fusion to fix it.

My workout routine is basically what my dr/physical therapist had me do, mostly a lot of core work, plus I'll throw in benches and curls.

Squats are good. Good for maintaining a shapely man-ass, and, lo and behold, good for your lower back support too. Unfortunately, for the last few months, my knees hurt worse and worse when I'm recovering from squats.

Anybody got any exercises that will accomplish the same goal (ass, lower back) without putting stress on my knees?