Just to throw a comment into the works, what is the appeal of doing these gruelling long distance events? Fun? Just something to achieve?
I ask this, because I'm a believer that marathons, epic triathlons, these kind of events aren't particularly good for you health wise. It's pretty unnatural to be running 20, 40, 100kms at a time. Not to mention the massive time investment that goes into training for such an event. And also by the sounds of it people come out of it feeling pretty damn sore and injured, albeit with a sense of accomplishment.
Hiking is another thing, it is consistent low-level activity that doesn't deplete the bodies energy stores or over oxidise the internal body. And is fun! And doesn't kill you!
I dunno, I just think exercise is more fun in short explosive bursts, and in a "playing" type context - playing rugby, soccer, sprinting, hiking, surfing. You only have to look at track sprinters (like Bolt) who is smiling and healthy looking and having fun and compare them to the guys running 10km (or marathon) track events at the olympics who look sick and in a world of pain.
Just my philosophy on exercise, take it or leave it
I just don't understand the current marathon craze over the past 10 years - who knows there might be a link there somewhere with running marathons and a chronic injury epidemic.