I dunno, I'd bet some can, though I just can't imagine running some parts. I'd think injury would likely come into play from a fall at some point, but who knows. Not saying many can, but every year I see people running on terrain here in the Whites that I have trouble hiking over. Granted, I'm slow and I suck. But I got pretty much blown off the trail (had to jump out of the way just south of Little Haystack) by the Dartmouth College girls ski team this past fall - they were running the Bridal Path - Franconia Ridge - Liberty Spring trail loop. And I mean flat out running the entire way. Came flying past me jumping off some 4 foot drops and such. They jumped off them - I slid down on my butt.