up with the older bmf racer in the united states. dr. sanjay gupta has the story. i love a challenge. kitty has been riding bmx bikes for nearly 30 years. at 69, i m the oldest bmx racer in the world. you talk about fun, hitting a turn at 20 miles an hour, can you imagine that? that s where the exhilarate comes. reporter: in the world of bmx biking, she s done more than break down age barriers. when i started racing, there were no women. not that they didn t want to race. they were not encouraged. i said, hey, ladies, we can make an impact. reporter: she work with sanctioning bodies to give adult women their own racing class. we went from two women, now there are over 1,000 adult women who are out there racing.