Running my regular 15k trail loop run barefoot as always but carrying my new Skinners this time (just in case ). Stone bruised my left arch some 9 kilometers in. Normally it is not a big deal and I just keep running to massage the spot so the bruise goes away faster. Not this time. Had some more bad luck and hit the injured spot on some rocks and tree roots two more times (it was really muddy). The pain got really intense at that point and there was still 6 more km to go to finish the loop with some rougher sections ahead. Put the Skinners on and finished easily with just enough protection for the bruised spot.. I really love them as emergency shoes for days like these. I only get these types of injuries maybe 3-4 times a year and it is always my arches that get bruised on sharp rocks. When I stop running immediately, the bruise gets swollen and stiff and more painful. If I keep running on it, it gets a nice massaging that encourages blood flow and after another 2-3 miles it starts to fade a good bit. Then it heals up completely in the next two days (icing it at home helps too). My balls of the foot and heels got pretty good fat padding and thick skin so those do get get injured so easily. Arches on the other hand are just a soft tissue with almost no padding - the nemesis for trail barefoot runners.