Best way to file toenails for marathon runners

Have you ever had black toenails after a long run? Have you ever lost a toenail after a marathon? Have you tried using goopy skin lubricants, or worn  bigger shoes that make you feel like you're wearing clown shoes? If you have, but you're still having problems beating up your toenails in your running shoes when run, I've got a simple solution that may actually help.  Today on the Doc On The Run Podcast we're talking about the best way to file your toenails if you're a marathon runner.