Likewise, in Michigan, James Sa sued Red Frog in federal court, saying he was paralyzed after diving in the mud at a Warrior Dash in 2011. He alleges in court documents that an emcee encouraged participants to dive in.

Red Frog has denied Sa's allegations in court documents and pointed out that all participants sign a waiver saying they won't go head-first into the mud.

Whether liability waivers signed by participants are enforceable depends on many factors, said Paul Figley, a professor who teaches tort law and legal rhetoric at American University's Washington College of Law.

Waivers have become more comprehensive, and now "will cover almost anything," said Figley. But, he cautioned, "you can't go too far. Your waiver can't say, 'No matter what we do'" you can't sue.

Essentially, organizers can still be held liable if they do something reckless, he said; the definitions of recklessness and negligence vary by state.

Wendy Davis, 45, had run obstacle races before, including a Warrior Dash and another called a Hell Run. She worked as a police officer and was in pretty good shape, so she felt ready for last fall's Extreme K Mud Run in the state of Washington.

But after sliding down a wet, tarp-covered hillside — "Gravity's Revenge" — she hit a pile of rocks at the bottom and broke a number of bones in her foot, according to a lawsuit she has filed.

"I get up every day, I'm limping," said Davis, noting that she has a plate and 13 screws in her ankle. "From my first two experiences, I would never have expected to go into something like this and think I'd have a major injury like this."

Davis and two other women with similar injuries are suing race organizers. "The obstacle lacked any design features which slowed or regulated the rate of the descent," they wrote in the lawsuit. "Instead, due to the steep pitch and long run, participants' descent was abruptly stopped when the participant impacted the rocks at the bottom of the obstacle."

The Silverdale Chamber of Commerce, which sponsored the race, is contesting the lawsuit. Officials declined to comment due to the pending litigation.

What the obstacle racing industry needs is a governing body to set safety standards, said Troy Farrar, president of the U.S. Adventure Racing Association, which sanctions team-based races that usually involve trail running, mountain biking and paddling.

The Texas-based association used to sanction obstacle course events, but stopped because it became difficult to get insurance, he said. "There were so many claims, people getting hurt, that our underwriters said we couldn't do them anymore."

Some of his biggest concerns are obstacles that involve water or significant height — that's where the most injuries occur, he said. He's also not a fan of running through fire.

Farrar said he's been in talks with some obstacle race organizers with the goal of setting up an organizing body with safety standards for such events. But he said the process could take several months.

In the meantime, he encourages people to try obstacle and mud runs, but to be aware of safety risks. "If you get to an obstacle you're not comfortable with, just go around it. They'll let you do that."

'I know the sorrow'

Last weekend, thousands of people descended on Budds Creek Motocross Park in St. Mary's County for a Warrior Dash 5K. As a band played covers of the Goo Goo Dolls and Green Day, an emcee at the starting line asked who had trained for the race — and who had trained for the post-race beer drinking. All racers were given a token for a free beer along with a warrior helmet with horns.

Some racers sported outrageous costumes, such as a quartet dressed as the rock band KISS, a group of girls in plaid Catholic schoolgirl skirts and several people in tutus.

Adam Lowe, a 31-year-old high school gym teacher from Mechanicsville, wore a dress suit. He had lost 55 pounds and figured he'd never wear it again, he said, adding, "It was just kind of a way to get rid of it and have fun." His wife, Darleane,a 29-year-old kindergarten teacher, agreed to be his "date" and pulled a pale blue formal dress out of the closet.

The Lowes, who have run the Warrior Dash at Budds Creek three times, didn't worry too much about injuries, but Darleane said her mother was a bit concerned after reading the waiver. The appeal of the race was to have a good time while exercising. "I'm from the country, so getting dirty and running around is too much fun," Darleane said.