Fatigue
The question is always pandered about on the internet - which is harder. A fast marathon, an Ironman or a 100 mile run. Pending the perspective of the person answering, the response will be very different. A fast runner, trained for three hours at the limit will view the Ironman and the 100 mile race as challenges. Finishing a race with the distance of run that is normally the race? Crazy. The ultra runner, used to covering long distances as steady, consistent paces might see the fast marathon as a challenge. The marathon is the warm up, not the actual race. And forget about swimming! And then the triathlete - more accustomed to covering the 100 miles on wheels, not on foot and then surviving the marathon after. I've done all three - at some stage in my life, so I have some semblance of an answer. There was the 2:47:17 marathon at the Top of Utah in 2003 that just missed out on the Olympic Trial Qualifying Time of 2:47. There were the Iron distance triathlons, including a 10:30 an...