In case you have not seen it, 'the Times' has an article up about vegan ultra-runner Scott Jurek called, Diet and Exercise to the Extremes.
I met Scott Jurek in 2006 when I was helping at the 135-mile Badwater Ultramarathon, which he won. A super nice guy, I chatted with him and his crew about his vegan diet and his training. I wanted to get an interview, but it just didn't work out.
The article mentions the 24 hour championships in France and I've found the live feed showing results. Looks to finish up at 1am, California time. Running in circles sounds absolutely miserable to me, but I imagine it is meditative in its repetitiveness. And it's not like he only does these races; quite the opposite. The Western States 100 and other 100 milers are trail runs, getting out in nature way more than most runners ever do.
In this terrific ESPN article he says, in regards to coming across a bear during a race,
Awesome. I agree.