Take Dr. Lisa Bliss, who won Badwater, the 135-mile race in Death Valley, in 2007, two years after having her two big toenails permanently removed. Previously, she had four times had a podiatrist cut away two misshapen nails that had grown back  painfully  into the nail bed instead of lying flat. So, she figured, why not just get rid of the nails?

Her online photo diary of the procedure  which is not for the squeamish  has become a forum for people who are trying to decide if the pain and weeks of recovery are worth it.

Dr. Bliss, from Spokane, Wash., still wears open-toed sandals and says that her nails “look better now than when they were black and blistered, and half falling off.”

The podiatrists interviewed for this article said that permanent toenail removal should be a last resort. Many blackened toenails can be solved by wearing shoes that aren’t too snug, or ones that accommodate the foot swelling that’s the norm with long distances, or by filing the nails flat on top.

However, advice for the average marathon runner who runs on pavement may be of little use to ultramarathoners, who run on trails and downhill slopes that jam their toes against the fronts of their shoes. “When you run that far and for that long, something is bound to happen,” said Dr. Jamie Yakel, a sports podiatrist in Denver.

Run enough 100-milers, go up and down enough mountains on manpower alone, and a full set of toenails starts to seem like a luxury. “Once you lose the nail once, it never adheres to the nail bed like it once did,” Dr. Langer said. “That’s why someone might be prone to the same nail getting beat up over and over.”