"Robic holds the UMCA's non-drafting 24-hour road record: 521.975 miles"

That is friggin' insane....average speed of 21.7 mph for a day straight.

Sorta reminds me of a runner by the name of Dean Karnazes out in California. Dude ran 100 miles to the start of a marathon and then clicked off like a 3 hour marathon. His goal is to someday run 300 miles in one shot.....I believe he's done 237 miles or something nuts.

http://www.ultramarathonman.com/