American ultrarunner completes barefoot trek of California’s John Muir Trail

It took Kenneth Posner 22 days to conquer the 210-mile route

WATCH: John Muir Trail FKT

Jason Fitzpatrick presents Unsupported, which documents four athletes as they attempt the Fastest Known Time on the 352K John Muir Trail

Three-time UTMB champion sets FKT on California’s John Muir Trail

France’s François D’haene sets a new benchmark for California’s John Muir Trail completing the route in less than three days