Man, I would quit for a while if that happened...
anyway, I find something strange - My bars are real low, actually as low as they can go, and I never get back pain. Loadsa times, at my local skatepark, I'm asked 'Doesn't you back ever hurt?' I'm like 'Strangely enough.. no.. unless i fall on it, but then it still doesn't hurt...' But.. yeah, I don't get it.. Even when I'm asleep, I can sleep with my back bent, all night, and it doesn't hurt. I think my back is invulnerable.. lol... I just don't get it.
But, yeah, We will face major problems when we're older. Mind you, saying that, BMXers, MXers Skaters, In the past who have BMX'd MX'd or skated, don't have problems with their backs, even having fallen on them so much. So, I think some of us will be okay, 6/10 of us wont.