A TENS unit force the muscles to "fire" and thus exercises them at the fiber level. It feels like a cross between a tickle and a massage. Startling at first, and can hurt if you set it too high. Start low.
The poor man's inversion is simply hanging from your hands and doing slow, gentle hip twists by criss-crossing your legs. This stretches your spine and takes pressure off your discs and any compressed nerves. Try it a few seconds at a time and work up. Quit if anything hurts or you suddenly feel dizzy. I use my garage door rails and a stepstool.
When I hang from the inversion rack I let my arms straight down and twist at the waist side to side, maybe 10-20 seconds then go up right, then repeat maybe 3-4 times. Help A LOT
