Endorphin junkies have a skewed sense of fun.

From the Tough Mudder Challenge. What?!

I spent the better part of an hour yesterday looking through photos spectators posted of the Tough Mudder Challenge that took place over the weekend in Pennsylvania. Ten thousand people (or complete idiots, depending on whom you ask) took part in the 10-mile challenge that required all participants to sign a “Death Waiver.” Over the course of the 10-miles, costumed (and some nearly nude) crazies completed eighteen obstacles in the freezing cold. They crawled through tire tunnels (The Boa Constrictor), slid down snowy ski-slopes on their butts (The Sweaty Yeti), crossed monkey bars – some rungs greased with butter – over a near-frozen lake (The Funky Monkey), and literally ran through fire to cross the finish line.

What did they get in return? A t-shirt, an orange headband, and a beer.

There’s something seriously wrong with these people. And there’s something seriously wrong with me because I think it looked like fun.

Even though the course involved live wires (Electroshock Therapy) and I read that one guy broke his leg in three places when he hit a greased monkey bar rung and fell into the lake below, I went to the website to see if the Virginia Tough Mudder was still open.

No, this was not a one-time event. Yes, these ridiculous challenges do sell out. All of them. Routinely. And Tough Mudder isn’t the only event of its type. There’s the Warrior Dash, the Spartan Race, and the Muddy Buddy, adventure races for those who think it’s not enough to run in a straight line for 5 or 10 or even 26.2 miles. No, it’d be more fun if there was a wall to scale or a cargo net to climb or a mud pit to wade through. It’s an exciting fitness trend that combines endurance racing and good, not-so-clean fun.

From Metro Dash in Atlanta.

Remember when you were a kid and you loved to feel the mud between your toes? Who said 30-year-olds shouldn’t get to enjoy that feeling too? Or the freedom of swinging from rung to rung on the monkey bars? Sliding down a slip-and-slide? Or feeling that your lungs would burst after an all-out sprint against the other kids in your gym class? We grown-ups are taking back the playgrounds in droves at events like these.

Since I’m not just an endorphin junkie and am also a mom to two young children, I don’t think I’ll be signing any “Death Waivers” to participate in Tough Mudder this year, but I will be taking part in another adventure this weekend here in Hampton Roads: Metro Dash, a 30-obstacle course designed by former Navy Seals.

Metro Dash was originally developed as “a mud run without the mud,” said Sean Ofeldt, Race Director for the event series, which is headquartered here in Virginia Beach. “We were looking at trying to create something different in the urban environment. We wanted to create something that wasn’t really in existence.”

In 2010, its inaugural year, Metro Dash events took place in 13 cities around the country. Participants would run 3-5 miles around cities like Houston and Seattle and complete a number of physical challenges. The Virginia event was held at Mount Trashmore in July, and the highlight was The Gauntlet, a multi-obstacle station that included tire flips, rope swings, weighted sled pulls, and a 12-foot wall.

For the love of it.

Unlike a traditional road race, however, Metro Dash had no timing chips, no clocks, and no awards. Those who were up for the challenge did it for the t-shirt and the satisfaction of knowing that they could complete it. And they did it because they thought it would be fun.

There were only a few hundred people there last year, but I was one of them. And even though I couldn’t feel my legs by the end and I struggled to lift my 5-month-old baby from the bed after his nap the next day, I had a blast and have been telling my fellow crazies about it since.

“Last year was kind of a test year as far as the idea,” Ofeldt explained. “People loved The Gauntlet and liked that it was a challenge, but there were a lot of people that would have liked to see it timed and placed.”

So this year Metro Dash is going to be a little different. Instead of a 3-mile run with a few obstacles thrown in, they decided to take The Gauntlet and multiply it. This year Metro Dash will be a timed, sprint-based, 30-obstacle course spread out over a football field. There will be tires to flip, walls to scale, ropes to swing, tunnels to crawl through, monkey bars to cross, and many other obstacles for grown men and women to endure and enjoy. Proving there’s a growing market for these kinds of events, Metro Dash will take place in 20 cities in 2011. The number of participants has multiplied too. Sunday’s race is sold out at just over 1,100.

“They’re definitely aggressive athletes. We get a lot of crossfitters, a lot of bootcampers. In designing the course, we wanted to create a level playing ground for all kinds of athletes,” Ofeldt said.

The popularity of these kinds of events has a lot to do with current trends in the fitness industry. While they were aerobicizing with Jane Fonda in the 80s, we’re pushing our physical limits with Tony Horton, the P90X, and functional fitness guru in this decade.

“People are moving away from the cardio and three sets of ten reps toward more functional fitness. It’s more fun, it’s more social, and people definitely get to see the benefits a lot quicker,” Ofeldt added.

The race will take place at The Virginia Beach Sportsplex on Sunday, and the all-day event is open to the public. Spectators will get a bird’s-eye view, and the facility will be open, with food and drink available, just as it would be for a game. Only instead of watching a soccer or lacrosse match, you’ll get a live-action version of ABC’s Wipeout, the Navy Seal edition.

And Sunday’s event is the first Metro Dash this year, which means we will be the first ones to try out the new set-up. We’ve got no YouTube videos to watch, no pictures on Facebook to study, no event reviews to read. All we have to go by is a sparsely illustrated list of 29 obstacles (one is a secret until Sunday morning).

The two-dozen moms of Team Stroller Strides and I have been hitting the playground with our kids, practicing our monkey bar skills, and box-jumping onto our couches and ottomans after bedtime to build up our confidence for this weekend. We’re ready to prove that we’re the Tough Mothers our team t-shirts will proclaim us to be.

Call us crazy, but we can’t wait.

For more information on Metro Dash Hampton Roads, click here.