(WBIR - Morgan County) This Sunday, thousands of runners will pound the inner-city pavement during the Covenant Health Knoxville Marathon. By the time the Knoxville race starts, a select group of extreme runners will have already been running for a full day and night in the rural hills near Wartburg at one of the most difficult races in the world.

The Barkley Marathons is an insane 100 mile race up and down the steep cliffs of Frozen Head State Park in Morgan County. Runners have 60 hours to complete five 20-mile loops through some of the most grueling terrain in the state.

Barkley Marathons founder and director Gary Cantrell may seem like the most unlikely race director when you walk up to the campsite the day before the race. The bearded man in his late-50s smokes cigarettes as he checks in an exclusive group of 40 chosen runners from across the globe.

"We get hundreds of applicants, believe it or not," said Cantrell. "People have to figure out how to apply on their own. They write an essay that explains why they want to run the Barkley. This year we have runners from 10 different foreign countries. I think every continent is represented this year except for Africa."

Cantrell concocted the race when he was an elite ultra-marathoner in the mid-1980s. The inspiration for the race was the 1977 jailbreak by James Earl Ray, the man who assassinated Dr. Martin Luther King, Jr.

Ray escaped from Brushy Mountain State Penitentiary at the foot of Frozen Head State Park and fled into the unforgiving hills. After running from authorities for almost three days, Ray had only traveled eight miles through the Park's torturous terrain when he was caught.

"I had been backpacking in Frozen Head State Park and remembered watching the news about James Earl Ray's escape. We were laughing at him only making 8.5 miles in 54 hours. I said in that length of time I could have gone 100 miles, because I was young and cocky. That stuck in my brain and we eventually set that out as a challenge to see if it could be done."

Cantrell personally travels the loop as he develops each year's course.

"I never send anyone some place I haven't gone. I'm an old guy with a crippled leg, so if I can do it they can do it."

The sinister race is known for delivering a big dose of humility to some of the largest egos in the alpine running universe. Since the race began in the mid 1980s, only 14 people have ever completed the race within the 60 hour time limit. The sadistic course takes runners through a cumulative climb of more than 50,000 feet.

"These are just modest sized hills in East Tennessee," chuckled Cantrell. "And they're steep. And there's a lot of them. You're going straight up and straight down."

The course itself is rarely on the beaten path, frequently forcing runners to navigate up and down cliffs through thick brush. Further complicating matters is the course route is unknown to the runners until just prior to the race.

"You don't know the exact course. You're out there by yourself all day and all night," said Cantrell. "After dark, what do you think route-finding is like up there at the top of the mountain in the fog? We have some special forces guys who have participated and they are really talented. They do a great job navigating."

Runners also do not know when the race starts. They set up at the campsite in Frozen Head State Park on Friday and wait for the sound of a horn that signals one hour until the race begins. That horn can blow anytime between midnight and noon on Saturday.

"We have blown it as early as 2:00 a.m. and as late as noon. You have to be ready."

Once runners set off on their journey, they hunt for books set at checkpoints in the woods. The runners must tear a page out of the book and return with it to prove they actually ran the designated course.

"You see me giving them their numbers. They get that page number out of the book and they bring them back. If they don't have one of their pages, their loop doesn't count. It has happened before and it was tragic for the guy who lost a page," said Cantrell.

The runners can always count on one portion of the course going through Brushy Mountain State Penitentiary. The prison operators have quietly allowed the runners to go through the tunnel that runs beneath the prison so they may reach the spot where James Earl Ray jumped the prison wall during his 1977 escape.

That small slice of predictability is counteracted by a lack of assistance on the route. There are only a couple of water stations along the entire 20 mile loop.

All of these factors create a situation that almost always ensures failure. Cantrell insists the ridiculous obstacles are not created in order to make success an impossibility. Rather, he wants the best in the world to have to perform at their maximum for the even the slightest possibility of success.

"Everyone should have a chance to put themselves to the test. Especially among ultra-marathoners, a big part of the culture is testing your limits. But you haven't tested your limit until you've tried something you can't do. Then you know where your limit is. It's right there where I quit. That was it. That was the limit," laughed Cantrell. "The time limit is not what causes most people to fail. They mentally break. You go 60 hours with no sleep, constant climbing and descending. You have to find yourself on a map. There are no pacers to find the way. You're out there by yourself all day and all night."

The impossible nature of the race brings unbridled joy when someone successfully conquers the course.

"I want them to succeed. Especially when they get on into it, you want them to succeed so bad because they've gone through so much. When someone does finish, you feel like you're elevated just by being there. It is one of the extremes of joy that can come with sports. Joy that you only get when failure was probable."

Runners who cannot complete all 100 miles can switch to a smaller goal. If they finish three of the 20 mile loops, they can officially say they ran the 60 mile "fun run" at the Barkley Marathons.

"It's just one more mental obstacle. It gives the runners an 'out.' One more thing that might make them decide to quit," said Cantrell. "We have some of the most incredible runners in the world here. There are guys here who have done every ultramarathon in the country. They've done 250 mile races through the Alps. They come here to test their limits."

Many people in East Tennessee may know nothing about the world-famous race in their own backyards. Yet, the race attracts international media who want to observe the unique race. This year, a film crew from Paris covers the campground with cameras for an upcoming segment that will air on "Interieur Sport" in France. The race has also been covered in the New York Times, Washington Post, and by other major media outlets.

A documentary about the Barkley Marathons has already been filmed and is in production.

*Reporter's note: This story was edited to clarify and correct a previous version that stated James Earl Ray escaped in 1977 using the tunnel beneath the prison. In fact, the tunnel allows runners to the reach the area where Ray climbed over the stone wall during his 1977 escape. Ray also attempted an escape in 1971 through a steam tunnel and was burned before turning away from the intense heat. He was then caught while searching for a place to make it over the compound's stone walls.

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