I've struggled a lot with piorrifmis syndrome. Stretching, the foam roller, and taking enough rest days are what help keep me running. I also have had plenty of black toe nails. I'll get one as my mileage increases (it's not my shoes, I'm sure of that) and by the time it heals, I've run my race, taken time off, and am ramping back up again. Bam- new black toe nail.