BENSON — As we walked toward the starting line in Benson earlier in July, Rita Beardwood pointed at my ankles and laughed heartily.
“Say goodbye to your socks,” she said.
Beardwood’s joke held a degree of seriousness. After several days of rain, anyone setting foot on the Shale Hill Adventure Farm obstacle course was going to emerge needing a shower and clean clothes.
Although my pristine white cotton socks labeled me a rookie, for the two men and three women clad in spandex and cross-country running cleats, the morning run through the course was just another workout. Still, Beardwood cut me some slack.
“Who knows,” she said, “you just might be cut out for this.”
After ringing a bell affixed to a pole at the starting line, we took off down the hill. A competition pioneered by rival mega-races like the Spartan Race (now with corporate sponsorship as the Reebok Spartan Race) and the Tough Mudder, the modern obstacle course is an event involving full-body effort — and suffering.
Every year, thousands of people sign up to run a course that offers a series of challenges: Contestants must, for example, leap over fire pits, throw spears at targets, crawl through flooded culverts, run through exposed electrical cables and much more.
Seeing the growing demand, course builder Rob Butler of Benson, Vt., designed one of only a handful of locations in the nation where athletes can train for these kinds of races.
AN EARLY START
At 5:30 on a misty Tuesday morning, I joined a group of athletes completing a month-long residency at Butler’s Shale Hill Adventure Farm. In addition to running the course every morning, that group completed trail runs up Killington Mountain and intense workouts with athletic coaches at Middlebury College. Some were just looking to get in shape, while others had their sights on elite-level competition. When I met them on the 10th day of their stay, all were starting to see some progress.  
Featuring 5- and 10-kilometer loops, the courses at Shale Hill don’t just wear you down — they chew you up and spit you out.
It was nothing like the muddy cross-country races I ran all over Vermont in high school, or the flat, fast races in track and field. Instead, the 10 kilometers pounded me into the mud and then slowly roasted me as the early July sun rose above the Champlain Valley.
But I wasn’t alone while I fought my way through the no-man’s-land of hay bales, barbed wire and ropes. Running alongside me through the fields, swamps and woods was Butler, the mastermind behind the course. Having designed and built the entire course and spent countless hours practicing on it, Butler practically floated over the rugged terrain, dropping pointers for me as we scaled walls, crawled through tunnels and hauled 5-gallon buckets loaded with rocks. 
The secret, he told me, is repetition.
“When you repeat something so many times, your body begins to accept it,” he said as I waded hip-deep through a bog. “If you listen to your body and treat it right, after three weeks, the motions become second nature.”
While it was hard to see how anyone’s body could accept some of the challenges as natural, Butler is a relentlessly encouraging presence; no matter your goals for the course, he’s got a way of getting you across the finish line.
At Shale Hill, he will house you, train you and even let you demo a pair of technical cross-country running shoes. Just expect no mercy from the more than 50 obstacles with names like “Heinous Hoist,” “Pick Your Poison,” “Haybales from Hell” and the ominous-sounding “Anaconda.”
It’s these obstacles that have given Shale Hill recognition in the obstacle-racing community. The course has been named as among the toughest in America by Obstacle Racer magazine, an accolade Butler says is due to the frequency and intensity of the obstacles, not just the length of the course.
For example, immediately after traversing a wall of hand and footholds, I crawled through a narrow box called “The Coffin,” which requires a person to climb up the inside by way of finger holes and knee-jams to keep from sliding back out the bottom. After two miles into the six-mile course, the best description I could summon was unrelenting.
“On this course, you don’t have to be the fastest runner,” Butler said. “You’ve got to be a universal athlete. You’ve got to be able to use every part of your body in order to succeed.”
Sometimes the barbed wire wins. Sometimes the rope spanning the duckweed-covered pond sends you for a dip. Vaulting an 11-foot wall like Clint Eastwood in “Escape from Alcatraz” can seem like a Herculean task.
But just over two hours later, Butler and I hustled our way back up the hill, crossed the finish line and met the group’s lone Quebecois, Vincent Larochelle, freshly showered and enjoying the morning sun in an Adirondack chair.
On the day of my visit, Larochelle cranked out a couple four-minute miles and finished the morning workout in about an hour. A carpenter by trade, Larochelle has had three podium finishes at international Spartan races in Canada.
With the help of Butler, he hopes to compete at the 2015 World Championships at Squaw Valley, Calif., in October, where 600 of the fastest obstacle racers in the world will race at elevation for $100,000 in prize money.
“What did you think?” he asked, offering a high-five.
Mud-covered, bleeding and sore all over, I managed a response.
“C’est bon,” I said. “It’s good.”