Is it possible that these guys lied about their mileage of vastly overestimated it?
I tend to think so - without GPS watches - how would you even know how far you're running? Also - without GPS, I think it would be very easy to embellish your totals..
I think lots of people lie about their mileage, which is why Strava is nice. You still get people who upload phantom "treadmill" miles - some probably lying, but it keeps us in check..