I think you're close but I'll agree with David. A marathon is not something that many people will just go do. Training for a marathon may be the better route?

I think you're close but I'll agree with David. A marathon is not something that many people will just go do. Training for a marathon may be the better route? These are often shorter runs (<10miles) during the week and 1 long run (<20miles) once a week. These are a bit shorter and occur more often which means more accessibility. How about an interface for creating/managing a marathon/race?