Over the course of 12 miles, Tim Bergsma dunked himself into frigid water, crawled through mud underneath barbed wire and hurled himself and his teammates over 12-foot vertical walls. He saw a man with a knee injury hop through a gazebo adorned with dangling electric wires, and joined his teammates to help him to the finish line. But ask Bergsma what it was like, and he won't tell you about the pain or his muck-filled shoes. He'll tell you it was a thrill.
The former University of Michigan men's soccer captain completed a Tough Mudder, a 10- to 12-mile course featuring obstacles designed to test participants' physical and mental strength. The event is just one of many adventure- and obstacle-style races throughout the country – others include the Spartan Race and Warrior Dash – that are attracting athletes and those looking for an adrenaline-pumping way to get in shape. Tough Mudder alone saw a rise in participation from 20,000 people in 2010 to more than 460,000 in 2012, according to the event's website. That popularity, however, doesn't come without risk.
"Some of the things are, quite honestly, too extreme, and for many people are not beneficial," says Grace DeSimone, editor of the American College of Sports Medicine's "Resources for the Group Exercise Instructor" manual. "Many of [these competitions] intentionally try and provide surfaces that are challenging, whether it's mud or it's wet or it's slick in some way." Participants with known medical conditions – like those with knee or spine injuries, and especially anyone with heart conditions or chronic ailments – should be particularly cautious, she adds. For people thinking of signing up, Brett Stewart, author of more than a dozen fitness books, suggests starting to train at least three months before a Tough Mudder. Events that feature a shorter course, like the Warrior Dash, don't require the same level of training and are smart choices for beginners, he says.
The varied obstacles of these competitions, from fire jumps to climbs over cargo nets, pose their own challenges to participants, and obstacles that call for sheer physical strength aren't the only risk on the course. Temperature obstacles, like the "Arctic Enema" in Tough Mudder races – an obstacle that requires competitors to dunk themselves in a dumpster filled with water that's kept just above freezing – offer their own set of hurdles to overcome. "If you put your body into ice, it's not going to function the way you would think it would in just normal water," certified running coach Jennifer Kimbel says. In water that cold, she explains, muscles constrict and aren't as effective as they are at normal temperatures.
Bergsma's experience helping the racer with the knee injury to the finish line is just one example of the types of injuries that can happen on any course. But Stewart cautions that those aren't the norm. "Rolled ankles are the No. 1 occurrence and that happens … all the time with just trail running, and that's just on normal trail surfaces," Stewart says. "Anytime people are off their feet they're going to have to land somehow and … quite often it results in a turned ankle or a sprained knee." Aside from those, he says, bumps, bruises and scrapes occur most often, and major injuries are not common.
Most races have medical staff on hand to keep runners safe, but Stewart says participants can do a lot on their own to prevent injury. "These races are very, very exciting, but you can't get carried away. You are responsible for yourself – from the start to the finish, you've got to get yourself there in one piece," he says. And getting yourself to the end intact can be a matter of proper precaution. Something as simple as keeping your full attention on the obstacle you're clambering over or under in that moment can be the difference between reaching the finish line or the medic's tent, Stewart adds.
Steps taken before a race can go a long way to ensuring a safe finish, and doing some research to determine what will be required of you is a muddy step in the right direction, DeSimone says. "If people want to learn more about it, go and watch one. Be an observer first," she says, explaining that seeing obstacles beforehand helps potential participants determine which are too extreme for their personal fitness level.
Experts say physical preparation is key – and that means a whole lot more than just going for a jog. Exercises that build upper body strength are essential, along with those that use participants' own weight for resistance. "[For participants], a lot of it is taking themselves regularly out of their comfort zone and preparing for the extra [exertion]," DeSimone says. She recommends interval exercises – short periods of extreme exertion – to prepare for the physical and mental exhaustion competitors face.
Stewart has similar recommendations, suggesting that participants engage in plyometric training – motions meant to stretch and shorten a muscle quickly – to prepare for obstacles that focus on more than just "lungs and legs." He recommends jumping and bounding actions to mimic obstacles that require dynamic movement. And simple exercises can fit the training bill, Kimbel adds. Exercises that use a person's body weight as leverage – such as push-ups, pull-ups and lunges – prepare participants for the rigors of the course and don't require a gym or trainer.
Obstacles like those littered throughout Tough Mudder and Spartan Race courses demand far more of participants than cardiovascular endurance. Vertical walls require competitors to hoist themselves up and over and often mean pushing and pulling teammates. Lugging large rocks and logs across various distances combines upper and lower body strength with endurance, and slim beams or unstable platforms over water and mud call for precision balance – and maybe some swimming ability.
All these maneuvers demand a level of fitness that requires the seemingly simple act of getting started, which highlights a major health benefit: "Anything that encourages people to work for the event, to get up in the morning and get out of bed and go strength train and run, I think that's a great thing," Kimbel says. "When people are motivated to finish races like this, it gets them out running, it gets them out training for it and that's a good thing."
And while some may find more traditional road races intimidating, the fact that just finishing an obstacle course can be counted as a success makes them somewhat more beginner-friendly, Stewart says. "The majority are the people that get off the couch and do something that's out of their comfort zone, make the decisions to eat better, even to train just a little bit better," he says. "The bottom line is they make a difference in their life and these races provide the goals."
[Read: 7 Mind-Blowing Benefits of Exercise.]
As tough as these courses are, Stewart says participants have the opportunity to learn from failure. "The best thing about obstacle races is they're challenging, but in the end they're forgiving," he says. "This is not life or death: This is a challenge, this is a race, this is still fun and the idea is to push yourself as far as you can and once you've gotten there, well, you've learned something. And the next time you show up you can work on getting a little better."