18Km approx.
It was called Roma No Limits. Results aren't up yet (i guess that will be anonimity gone once they are! In anycase it is not like there are thousands of people running barefoot in rome!)
It is run by military types so there was a whole bunch of drills that had to be performed along the way. The first 600m included a whole bunch of obstacles to climb and jump over as well as running in a lake (thigh high at my height) and climbing on ropes to get on a bridge. Plus it rained last night so it was amazingly muddy.
It did not feel fanatically extreme even though they present it that way to make it more alluring i suppose. I was mostly interested in the environmental aspect, contact-with-nature feel, whioch we got plenty of.
Anyway I ran in my Vibrams 5Fs, the ones that gave me the tendon problems in May. And empirical news is that it truly was a "lacing" problem (as in too tight) as opposed to an overall design problem. This run was one heck of a biomechanical test. I value being self-critical and i didn't feel it was objective enough to "blame it on the shoes." Takes two to tango, as they say. Not always, but frequently...
So the point is, the lacing is really critical and has to be done very carefully. But once done, it felt very functional. And i felt very light.
So the winner came in 1:55 he said. I ran without a watch and i figured out i ran anywhere between 2:18 to 2:20 from my closest co-runners. Only one water stop, bery late in the race. I ran the wrong way 3, repeat 3, times and that was brutal. Maybe worth a few positions and some minutes. If i had eaten my toast and honey before hamstrings started to twinge, it could have been another minute or so. But the amaziong thing was the honey felt like it went like an IV and within 4-5 minutes i felt ok again. Wild.
Overall a great day.
I sincerely wish you get better.