When Pheidippides ran the 40-odd kilometres to report the Greek victory over the Persians to the people of Athens after the battle of Marathon, legend has it he collapsed on the spot and died. But it is little known that he was reputed to have run 240 kilometres in the previous two days. So the perils of ultra-distance running have been apparent from the earliest days.
http://mg.co.za/article/2011-09-05-going-the-distance-can-be-too-far/
http://mg.co.za/article/2011-09-05-going-the-distance-can-be-too-far/