Running a 5K, a marathon or even an Ironman is hard enough. But try adding electric shocks, crawling under barbed wire, running through ice-cold pools -- all while caked in mud?

Surprisingly enough, events with obstacles like these (and many more) are gaining popularity all over the world.

Obstacle course competitions like Tough Mudder and Spartan Races are designed to challenge even the most athletic types to get down and dirty. Regular Joes and Janes are getting in on the action, too, by embracing the slop despite the dangers that lie ahead.

Spartan Race’s Joe DeSena got the idea for the event while snowshoeing with co-founder Andy Weinberg in 2004. They were inspired by distance runners and triathletes, but not in the manner you’d think.

“What annoyed us both: You’d find an Ironman or person who seemed so driven, so tough,” DeSena said. “Invariably, what tends to happen is if there’s really bad weather or something’s not right, you find these guys quit the race. We couldn’t reconcile that, so we said, ‘Let’s create a race actually intended to break people.’”

They began with the Death Race, which eventually evolved into the Spartan Race filled with obstacles like running over fire and throwing a spear. Participants who skip or fail to complete one of these challenges are penalized with 30 burpees (a movement combining push-ups and jumping jacks). The idea, DeSena said, is to stretch competitors outside their comfort zones and create an Olympic-like event to time and rank participants.

While events like Tough Mudder have some similarities – challenging obstacles and a whole lot of mud, as the event’s moniker suggests – they're less about competition and more about cooperation.

Racers running up a muddy hill

Tough Mudder competitors jog (and crawl) up hills at Whistler in Vancouver. 

“Tough Mudder is about pushing yourself to the limits and helping others to do the same,” the event’s operations team wrote via email. “When you do a Tough Mudder, you’ll meet new people and overcome challenges when you get through the course -- together.”

The obstacle run began in 2010 and has since grown exponentially. Tough Mudder events drew 20,000 participants in its first year. In 2013, 50-plus Tough Mudder events generated 1.3 million entries. Like Spartan Race, the appeal is stretching limits.

“We know that everyone has challenges they’d like to overcome, and whether it’s in life or on the course, Tough Mudder is able to help participants tackle challenges head on, and do it with the help of their fellow Mudders,” the team explained.

A.J. Pawliw, who competed in a 2012 Tough Mudder event in Englishtown, N.J., was drawn to the race for multiple reasons. “The original appeal for participating was to give myself a legitimate physical challenge and a justification for paying my gym dues each month,” he said. “Given that I ran with a group of close friends, the camaraderie aspect of the event had its appeal as's sort of a throwback to the high school locker room.”

Events like these are satisfying for those who finish – only 78 percent of participants make it to Tough Mudder’s finish line – but injuries are a risk, as they are in other sports or races. According to DeSena, 200 out of 10,000 runners at a recent Spartan Race in Georgia sustained an injury.

Even with those inherent risks, the popularity continues to grow. Perhaps it’s because both events and other races of their kind tap into something our bodies are missing in today’s society.

“Our ancestors used to hunt wildebeests and swim across raging rivers,” the Tough Mudder team said. “Now we pull roller bags with our index finger while staring at our smartphones and sipping coffee drinks with names so long we can’t remember them.”

Or, as DeSena concluded, “I think it makes you feel human again.”

Up to the Task?

Are you inspired to run one of these races? Here are five ways you can prepare to tackle an obstacle-filled challenge:

1. Adjust your strength training to fit the race. Tough Mudder’s operations team said “pull-ups will get your upper body ripped for Funky Monkey, and lunges will strengthen your legs for the slog through Mud Mile.” DeSena added burpees to the list as well.

2. But don’t forget the cardio! You still have to run miles through the challenging elements, so building up endurance is key. “It's important to be comfortable running five or six miles straight without feeling the need to collapse,” Pawliw said. “All the upper body strength prep is sort of secondary to that.”

3. Eat before you run. And don't forget to pack something to snack on and drink along the course. Pawliw remembered eating bananas while passing by competitors cramping up miles away from the finish.

4. Dress for success. Tough Mudder’s website suggests “lightweight stuff that dries quickly” along with regular running shoes. More specifically, as Margaret Schlachter penned for Spartan Race’s site, don’t wear cotton or white.

5. Start taking cold showers. That’s one from DeSena. Why? “It helps you get more gritty.”