I've been feeling quite a bit of soreness recently when I tighten my corset muscles to lengthen my back. I figure this could either be a) good soreness as my spine gets used to being stretched out, or b) bad soreness from inadvertently compressing the disks with the extra muscle tension. When I am tensed into the 'greyhound' position, I do see curvature in my back but I have a hard time telling what is excessive sway and what is correct lumbar curvature. I try as much as possible to stretch up and forwards to avoid swaying.
How can I test that what I am doing is correct and not going to cause problems?