I have nothing going in like that, although I have strained my lower back a couple of times in the past couple of months working out. Standing up straight was a real pain... literally. Fortunately, that would only last a day, and then it would just be stiff another day or so, and it would be all good. The second time (which was last week), I distinctly felt it gave way and immediately knew I was screwed. Finished my workout, though. The pain would set in later.