In his Runnersworld article (yes, Runnersworld), he claims he only ran 36 mpw at the peak of his training. And then he goes out and does an ironman every day - that's 26.2 miles a day, 183.4 mpw - for 50 days! Now I get that he took it slow, but still being on his feet for more than 4 or 5 hours of running every single day for over 7 weeks, probably mostly on pavement... without even running 40mpw in training... how do you not get injured from that? And that's just the running part, then you throw in 112 miles of biking and 2.4 miles swimming every day... did they serve as a sort of "recovery" as they were nonimpact? You'd think it'd only up the risk of injury though. Plus he claims he got about 4-5 hrs sleep a night which doesn't exactly aid recovery.
And then here I am I try to maintain 80mpw after a slow buildup and I'm injured after a couple weeks. Figures.