CHICAGO (CBS) — This year’s Chicago Marathon will see the largest contingency of wheelchair racers in the event’s history.

69 wheelchair athletes have registered so far, the largest in the event’s history and double from last year. 23-year-old University of Illinois student Tatiana McFadden is going for her third Chicago title.

She says the course in Chicago is a challenging one.

“I think that is what keeps driving me back and it’s tough. It is a really tough race. It can be stubborn. I flatted several times in this,” said McFadden. “It is a really great race.”

McFadden rode her first ever marathon here in Chicago and won it in 2009. 45,000 runners are taking part int his year’s Chicago Marathon.

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