When I was in law school, I suffered from that exceptionally common ailment, lower back pain. There was a lovely gym with all sorts of brand new equipment with exciting names waiting for me to try it out, so I systematically gave pretty much every device a shot, from the rowing machines to the ellipical something or others. Nothing worked. My back still ached. And ached.
Finally, one day, I said, "Enough!" and stopped with the exercise at the gym, though I did walk a fair amount, as it was unavoidable. Bingo! Back pain gone!
My single sample has now been proven scientifically. Exercise does not help lower back pain. Read about it here.