i went the other direction and quit racing. i have 2 fusions that occured naturally after losing the discs. (no surgery) trust me, you can't imagine the pain.
at the time (late 90's)i was running in the high 7's with aspirations of going faster. the racing was painful but doable. my biggest concern (and the doctors too) was in the event of a crash some bad things could happen. i'd like to keep walking so i gave it up. sometimes i miss it but most of the time i don't. i'm too busy now with the machine shop and engine building to worry about it.