The Tough Mudder bills itself as "Probably the Toughest Event on the Planet." But after a wrongful death lawsuit was filed last week a year after a man drowned at one of its events, some wonder whether the extreme obstacle course -- and other similar competitions (including one 24-hour challenge called the You May Die Death Race) -- are too dangerous.

While risks are outlined in race waivers, and most events encourage competitors to talk about the competition with a doctor, emergency room staff who treated participants after an event in Pennsylvania said that it's "unlikely that participants comprehend" the actual risks involved.

"This isn't just the facade of danger," said Marna Rayl Greenberg, who published a case review with colleagues after a Tough Mudder event last June sent 38 participants to the emergency room. "You might limp for the rest of your life. Does that seem real to you?"

The World's 8 Most Grueling Endurance Events

Extreme sport expert and blogger Kim Kircher agrees that understanding the risk is critical to running a responsible event.

"I do believe that it is important for people to push themselves, and that our culture is way too coddled," said Kircher, which "makes you afraid to try things and unable to grow." ... but "you have to know willingly that you are doing this."

In the case review published by the American College of Emergency Physicians, the authors noted that while many of the injuries were sprains, fractures, cuts, knee injuries, and heat exhaustion, a significant number seemed to be caused by electrical shocks. So while the injury rate was similar to other endurance competitions, the nature of the injuries was quite different.

7 In-Your-Face Races to Try

"We wrote this because it hadn't been well documented that significant injuries could happen," Greenberg said.

Not surprising, considering that such events have exploded in popularity in the past few years. 1.3 million people have done the Tough Mudder alone (and at least 4,000 of them have gotten Tough Mudder tattoos).

One problem may be that some of the obstacles are impossible to prepare for, Greenberg said. Most athletes prepare for a marathon or ultra-marathon or Ironman by training: running, biking, swimming, strength training. But many of the obstacles presented in Tough Mudder-type races can't be trained for.

"You can't train to go through these kinds of shocks," or even to jump into frigid water, Greenberg said.

A woman in the 2014 Whistler Tough Mudder competition reacts to jumping into a muddy ice bath.toughmudder.com

If you're a novice, she said, it might make sense to read through the list of obstacles and avoid those that don't have any recommended training.

"Clearly you can get dirty, take a few risks and not get hurt," she said.

Risk-taking, however, may not look the same to everyone. Kircher points to research that certain personality types, even different brain chemistry, crave risk.

Alt Race Options for Out-There Weekend Warriors

"Granted, it can't be too dangerous for the culture to accept it, but it has to be tough," Kircher said of Tough Mudder-style races. "And when you talk about really risky things people are doing of their own volition, it's really not a question about their safety per se, but the costs to society as a whole...We can't tell other people they can't take risks unless they're hurting the culture as a whole."

Other research has proposed a theory of "risk homeostasis," suggesting that people are going to take a certain amount of risks no matter what. A race car driver, for example, may counteract their aggressive behavior on the race course by driving in the slow lane on the highway.

"If that's true, it seems like this race could be where people are really putting themselves out there," Kircher said. "They're not hurting anybody else, and they're doing it willingly. Maybe then you feel like you don't have to do drugs."