Thank you for replying Physiobob. I actually have had xrays this year and no spondylolithesis.

But thank you, it never occured to me that it could be a nerve issue. Thinking about the stretches they all do include the rotation you mention.

I didn't mention that these same muscles feel chronically tight when I stretch them statically- I don't know if that makes a difference. Hamstring stretch is a forward bend, interal obliques is a back hyperextension over a stability ball, adductor stretch is a supine v-stretch with legs up a wall. All of those also involve the lower back.

It makes me wonder how to tell the difference between true muscle stiffness and nerve-related (apparent) muscle stiffness...