Gentle stretching works for me. Muscle relaxants for the spasms (but haven't needed them since the original injury back in 1974 or so).

I find that if I keep the muscles on the sides of my back strengthened (I work out with free weights when I remember to -- usually not often enough) I don't have a problem -- unless, of course, I do something stupid like reaching to pick up a heavy recalcitrant cat from inside a "cat cave." Sigh.

Linn