You can't complete a Tough Mudder alone — the grueling 10- to 12-mile course with more than 20 obstacles designed by British Special Forces is set up to make sure of that.

And of the expected 14,000 people participating in the Mid-Atlantic challenges this weekend in Gerrardstown, W.Va., perhaps no one understands this fact more than Baltimore resident Kate Robertson, 29, and her team.

Helping one another navigate obstacles that border on cruel and unusual punishment — such as army-crawling on a layer of ice to avoid electric wires overhead — proves even more challenging when one of your teammates is a paraplegic. But Robertson said her team, which is participating in its second Tough Mudder, is dedicated to helping teammate Mike Murphy complete every part of the course, even if that means lifting and carrying him at times.

“It's the greatest expression of camaraderie I've ever been a part of,” Robertson said of her first Tough Mudder.

At last year's Mid-Atlantic challenge in Frederick, there were moments in which team East Coast Beast Coast wasn't sure it could get Murphy, who has been a paraplegic since 2007, through certain obstacles.

Climbing the greased and muddy quarter-pipe known as Everest was the most difficult. As the rain poured, Robertson and her teammates tried unsuccessfully to create a human ladder for Murphy to climb.

When this tactic didn't work, they were at a loss. Murphy's mother was on the sideline, telling her son to skip this one — it was too dangerous. But with teamwork and help from a group of firefighters who had already completed the obstacle, Murphy made it to the top.

“It's hard as heck just to get yourself up there,” Robertson said. “Seeing him get to the top was pretty amazing.”

Their experience exemplifies the Tough Mudder philosophy that CEO and founder Will Dean was looking to foster — focusing on camaraderie and the overall experience rather than competition and personal-best times.

“Tough Mudder is a challenge, not a race,” spokeswoman Ashley Pinakiewicz said.

The course is indeed a challenge — only about 78 percent actually finish, on average. But participants, more than 700,000 to date, are more than willing to put themselves through grueling physical conditions. Since its beginning in 2010, Tough Mudder has expanded to events as far as Germany and Australia. The company has also raised more than $5 million for the Wounded Warrior Project.

The cooperative aspect was a huge factor for Robertson, who signed up for this year's event two weeks after completing her first Tough Mudder.

“I've always been a team athlete. I've never really found pleasure out of individual sports,” she said. “The glory of celebrating with others is so much more meaningful.”

Another Baltimore participant this weekend, Erin Carrington Smith, said that training for a Tough Mudder has motivated her more than an individual event could have.

“It's not just physically challenging, it's mentally challenging,” she said. “I've always been sort of the person who doesn't push myself physically and doesn't want to be in pain and doesn't want to get hurt, and so this is a really big challenge for me.”

Carrington Smith remembers sitting in the car in the rain watching her husband, Kieran Smith, participate in last year's event, thinking she would never put herself through something like this. But after signing up “on a whim,” she focused on training, lost 30 pounds and was set to tackle the Tough Mudder on Saturday — her 30th birthday.

But there are many aspects of a Tough Mudder one just can't train for, such as the first obstacle in every event — the Arctic Enema. Participants must jump into a dumpster full of ice water and swim beneath wooden boards to reach the other end.

With the advantage of having one Tough Mudder under her belt, Robertson said she was “preparing herself mentally to be freezing immediately.”

Robertson feels more confident this year, knowing slightly better what to expect, although she said there are always aspects you can't prepare for.