ruptured l5-s1 last fall. severe sciatica in my right leg. did the pt thing all winter. they told me not to bike as it would make my injury worse. I listened to them for about two months and once spring came started putting in the miles again. cycling has definitely help my back, but I think any kind of activity short of running does. I also stepped up my overall health, eating better, loosing more weight and found that pilates has helped a lot. mostly bridges with a fitness ball and planks. recently started swimming too. now my sciatica and pain is gone. all i have left is some nerve damage making my small toes a little numb. My days of moving heavy objects is over. good luck with you injury.