Why is it that we labour under the delusion that having black, dead, or missing toenails is a badge of honour in running? If this was our teeth would we feel the same? I doubt it. I would suggest that kicking a tree root or rock with significant force should be the only reason to lose toenails. In more than a decade, the only toenail I have ever come close to loosing was after attempting to uproot Tane Mahuta (the god of the forest) with my toe. Want to avoid turning your feet into nail graveyards?