Marathon Glory Comes With a Price

"My toenails turning black happened before," said Jessica Horne, 26, an amateur athlete who will be running for the second time in the ING New York City Marathon this Sunday.

Bloody toes are just one of the many painful and extreme physical casualties of running a marathon.

"But it wasn't until this intense, long-distance marathon running that I discovered everything else," Horne said.

Horne is just one of thousands of non-elite athletes joining the marathon boom in the United States. And as more amateur athletes take up the sport, more people like Horne are discovering the "everything else" side effects that come from pushing their bodies literally to the limits -- black toenails, missing toenails, stomach problems and bloody appendages.

In 1970, the New York Marathon only had 127 runners. By 1976 it was 2,090. Last year, 39,265 people started and 38,607 finished.

"This sport is exponentially increasing," said Dr. Lewis Maharam, medical director for the ING New York City Marathon and a columnist at runnersworld.com.

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As an athlete during high school, Horne had already experienced the infamous "black toe" before she started training for a marathon.

Black Toes and Other Problems

Black toe, technically called subungual hematoma, is just a simple bruise from repeated impact that turns into a pool of blood under the nail.

Bruce Williams, president of the American Academy of Podiatric Sports Medicine, ran in six marathons and treated hundreds of marathoners in his career.

"We've seen lots of things from lots of blisters, black toenails, in-grown toenails, stress fractures," said Williams. "Just about everybody is going to get a blister."

Unlike many other sports where athletes tear ACLs or break bones, the majority of injuries in marathons tend to be overuse injuries, said Riann Palmieri-Smith, a certified athletic trainer at the Bone and Joint Injury Prevention and Rehabilitation Center at the University of Michigan in Ann Arbor.

"One of the biggest things that happen when people injure themselves is they're really running too far at a low intensity, or they are rapidly increasing their intensity," said Palmieri-Smith.