The photo of Wang Jiaxiong taken right before his death during a bicycle stunt has created a lot of interest. Lately, it seems that all the "daredevils" are media creations that commit pre-packaged stunts that look hard but are ultimately safe. They are designed to sell soda pop on FOX, or NBC, or ABC. Not that there is anything wrong with escapist entertainment. It is just that no one is gonna get hurt. There is no risk. That is what makes a daredevil.
China showed us someone doing the stunt for the sake of it (and for the glory, of course.) It is too bad he did not make it. It would have made an even better picture to see him land triumpantly after his bike soared right over the wall. More detail is available in this article, Deadly stunt.
The history of these folks is fascinating. I have put up a couple of links to get you started.
I have found it helpful to do the stretching exercises my physical therapist recommends. Do some core strengthening exercises, such as the ones highlighted at The Mayo Clinic. By keeping your core strong, your back won't put itself in a position to cause that sciatica pain you are having.