[pjreddie]

Well walking is way more dangerous per mile than driving, this was touched on by Steve Levitt in Super Freakonomics, it looks like in Britain the mortality rate is about 10 times higher per vehicle mile http://road.cc/content/news/68212-dft-casualty-statistics-ra....

Of course, that is general foot transportation. Marathons have different risk factors, you aren't going to get hit by a car (if it's a well organized marathon with a set path and stuff) but I bet there are a lot of medical issues that arise from marathons and overexertion. If I were a betting man, I'd think the marathon was probably more dangerous.

[mongol]

Risk per hour is what I am personally more interested in.

[pjreddie]

That's interesting, I don't generally think to myself, "Hm, I could go drive around for an hour or I could go for an hour long walk", I usually think "Hm, I could drive to this place or bike over there (I don't usually walk)". Although I also don't really think about the risks of everyday activities anyway, so who knows.

It's really difficult to compare the risks of walking vs driving since usually they aren't really interchangeable and they have such different use cases. But the original comment was about running a marathon vs driving the same distance.