When the Tough Mudder descends on Westbrook’s Sunset Ridge Golf Links this coming weekend, it will bring with it roughly 15,000 participants, all of them determined – energized, focused and confident. At least, that’s how they’re likely to feel when they begin the course. How they’ll feel when they finish, well, that’s anybody’s guess.

Not everyone does finish, after all, and it may not be rational to expect them to. The Tough Mudder – which takes pride in its toughness, billing itself as “The Toughest Event on the Planet. Probably.” – is a 10- to 12-mile obstacle course that somewhere around one in five challengers won’t finish.

Let’s think positive, though: 78 percent do reach the end, according to the organization’s website. That’s a lot of success, given that more than 100 Tough Mudders have been held since the inaugural running in 2010. Eighty percent of those who join do so as part of a team.

So what, exactly, do they face, once they set their first foot in all that gooshy mud? Tough Mudder courses come in a smorgasbord of types: Arena, Backwoods, Open-Range, Off-Road, Mountain and Muscle. Westbrook is likely to see a variation on the Backwoods theme, which is described online as “taking nature running to the extreme.”

“One of the reasons we like Sunset Ridge,” says Ben Johnson, part of Tough Mudder’s design team, “is because there’s a lot of natural terrain we can utilize, to make sure we’re not just putting people down a straight, flat run. There’s a lot of naturally super-muddy areas, tighter terrain, that’s going to be a good backdrop for some of the obstacles.”

Approximately 20 different obstacles will dot the course, each named. Some names are (ironically) reminiscent of Ben and Jerry’s flavors – e.g., “Funky Munky.” Others are wittily non-PC: “Arctic Enema.” Still others are intimidatingly straightforward, like “Everest,” or a little bit unbelievable, like “Electroshock Therapy.” Yes, electricity is involved. All are designed to push contenders beyond whatever limits they thought they might have.

The above are all classic Mudder. But three roadblocks are new in 2014, and obviously to Westbrook: “Pyramid Scheme,” “Pole Dancer,” and “Fire in Your Hole.”

The first of those is an update on an old standby. “One of our most popular obstacles to date has been Everest,” Johnson says. “It’s sort of a concave, quarter-pipe that people have to run up to; it’s normally greased. We changed the traditional design for that this year, created Pyramid Scheme, which is a flat incline at a pretty steep angle that requires teamwork. Other people help push you up this muddy, muddy wall. It’s nearly impossible to get up it yourself; it requires you to stand on your teammate’s shoulders.”

Pole Dancer uses two parallel bars, akin to those male gymnasts perform on. However, the Mudder adds an incline to the mix. “Using your hands, you sort of have to walk across the muddy pit,” Johnson says. “It really requires some upper body strength; it’s going to be hard on your shoulders.”

Fire in Your Hole is actually available only to repeat participants, as it’s included on the course’s “Legionnaire’s Loop,” accessible for anyone who’s done two or more Mudders. The obstacle itself is “a slide,” says Johnson, “that takes you from about 25 feet in the air down through a 4- or 5-foot wall of flames into a pit of mud, which is super-exciting. It looks super-steep when you get to the top of it. It’s really fun. One of our most well-received new obstacles.”

In addition to the aforementioned obstacles, the Mudder’s architects always include some secret challenges – facets of the course that nobody knows about until race day.

“Our course designers have been doing this for four years now,” Johnson says, “so they know how to take some of the natural elements and turn them into unique hazards. So along the course you find pits, some excavated areas where we sort of build whatever we think makes sense for that space.”

Johnson recommends people begin their Mudder training by simply adopting the proper perspective.

“It’s going to test all-around strength, but mostly mental grit. So the first idea is coming into it with the right attitude, working with your teammates and making sure you’re really going to spend time helping people over the walls,” he said.

As far as the physical demands, Johnson suggests prospective Mudders be sure they can run five or six miles, and at least be able to do a handful of pushups, pull-ups and other basic bodyweight exercises comfortably.

“Our advice is always start with what you’re dreading,” Johnson says. “If you haven’t been running enough, get used to running again.”

33-year-old Stacey Coleman, executive director of My-FIT-24 on Railroad Avenue in Gorham, is leading a team of 20 into the Mudder, alongside her husband, Jesse. The pair are not only fitness pros, they’re also Mudder vets. “Back in 2011, when it was a brand-new thing, we did it at Mount Snow, in Vermont,” Coleman says. “It was a lot of fun.”

None of My-FIT-24’s other team members have Mudder experience, exactly, but some have tackled obstacle courses in the past (the gym holds them twice yearly), others enjoy triathlons and the like, and still others have achieved profound personal fitness goals, such as huge weight loss.

“We’ve got really cool stories about people who, three years ago, never thought they would run,” Coleman says.

Coleman qualified, in fact, for that year’s World Championship, which tasked competitors with completing a course as many times as possible in 24 hours, so she’s undeniably qualified to train newbies for the event. She’s focusing her team especially on the Mudder’s out-of-the-ordinary physical requirements.

“They’ve been working really hard on pulls and hanging events, that your body’s not used to doing on a regular basis,” she says. “Obviously a lot of running, hill climbing; we’ve been using playground equipment. It’s been a lot of fun, and I feel like they’ll all be able to complete it.”

The Mudder isn’t timed, which frequently catches interested parties off guard.

“It’s a totally different mentality than you would see for a triathlon or a marathon,” Johnson says.

In such events, athletes typically look to set personal bests by the clock. In the Mudder, they look to set interpersonal bests, by strengthening the bonds of friendship and camaraderie. In fact, it’s hardly uncommon for an athlete from one team to lend a hand to an athlete from another team.

“It’s more about camaraderie and personal accomplishment, rather than racing,” Coleman says, “which is what I really like about it. So I tell [my team], ‘Even if you have to walk part of it, just keep going. It’s all about facing your fears and doing something you haven’t done before.”

So, how will those 15,000 adventurous souls slated to take part in Westbook’s Tough Mudder feel after navigating the Herculean series of labors described above?

Mud only knows.

The Tough Mudder registration fee, which ranges from $145 to $220, gets one access to the course, the challenges and the satisfaction, but it also gets one gear: a headband, a T-shirt, and, oh, a “hard-earned beer” at the end.