If you are interested in seeing how tough your Ironman race is compared to others you should get to know this site:
He also breaks down several marathons.
It’s interesting that Ironman Louisville, which I’ll participate in this Summer, Lord willing, is ranked as the fourth toughest. And Ironman 70.3 Branson, which I completed twice, is ranked as THE TOUGHEST HALF IRONMAN. But looking at the numbers it’s hard to immediately see why. And the fact that its the toughest, but not by a lot, further complicates the analysis. Not being a statistician my guess is the tough, mountainous bike course takes so much out of even the strongest riders that there’s not as much left for the run as the athletes are used to having. So a slower bike combined with a slower run pushes the overall average up just enough to make it the slowest 70.3 race. Additionally, if his numbers include the 2011 race the results may be skewed a bit because we raced through torrential rains. There was a huge thunderstorm that day in Branson. I remember vividly running through ankle deep runoff. Soaking wet shoes and clothes did not help any of us go faster.
As far as Louisville goes, I hear the heat is the biggest contributing factor to the difficulty there. I do not look forward to racing in August Louisville heat and humidity, but I shouldn’t have any trouble finding heat and humidity to train in here in west central Missouri.
At any rate, check out the website. I’m not getting paid or anything to refer you there, I just appreciate all of the numbers and the advice.