As I understand it, some folks with have high VO2 max readings naturally. Lance Armstrong apparently had a spectacularly high reading from the beginning. It sounds like someone might test beginning racers to see if they have the makings of the next Lance, which I guess gives them a basis to suggest more training.
I also understand that VO2 max increases with training. The average shmoe, like you and me and 99% of the rest of the world, will improve, but Lance on half a lung probably will still beat us. Such is life.