Everyone stimulates a locked muscle. We unlock it first.
The ache, the heavy legs, five minutes of walking becoming your ceiling — that's a spine whose deep stabilisers have gone quiet. The multifidus sits too far down for anything you can buy at a pharmacy to reach it, and once it stops firing, every other muscle in your back starts compensating. That compensation is most of what you're feeling.
Here's the part nobody explains: a muscle that has been guarding for years doesn't respond to electricity. It braces against it. Which is exactly why the TENS unit in your drawer stopped working after week two.
Heat runs first and softens years of protective tension, the same way a clinic warms you up before hands ever touch you.
Now the stimulation lands. Around 600 deep contractions in twenty minutes, pulling the multifidus and the surrounding stabilisers back into the work they stopped doing.
