More people are taking on the challenge, but more people are also getting hurt.
First of all, this isn't a race for the weekend warrior. It is a 10-12 mile tough obstacle course.
I met up with a local team training for it, and I talked to an orthopedic surgeon about what he thinks of the "Tough Mudder."
They call themselves the Mud Run Junkies. Every week they hit the trails, running up and down, over and around rocks, through streams and mud.
Lead by Shan Egan, they're training for what some enthusiasts call "possibly the toughest event on the planet."
Video of a previous Tough Mudder Race shows how runners crawl, climb, jump and swim. But it's not only dirty. It can be dangerous.
That's something Michele Dougherty picked up on during her first Tough Mudder.
"There were a lot of people being taken off in stretchers, and a guy that we know blew out his knee," said Michele.
Dr. Robert Frederick of the Rothman Institute at Riddle says emergency rooms see an uptick in business when the Tough Mudder comes to town.
"Certainly all the trauma that we see from big automobile accidents or football games or hockey games can occur during these competitions," he told Action News.
Those include broken bones, such as legs, ankles or collar bones, or dislocated joints.
Dr. Frederick says most Mudder-ers escape unharmed. But all should be aware of the dangers and TRAIN for the event, because the more tired you become, the greater the risk for injury.
So you need to build your endurance and get used to running on uneven surfaces, twisting, turning and jumping. And you also need to build upper body strength.
"A lot of pulling yourself up, jumping over things. So yeah, that comes in handy," said Dr. Frederick.
And when it comes to the obstacles, the doctor also recommends "not trying to push through them with reckless abandon, but taking your time and gradually going through them. Because you never know what you are going to run into."
You may be thinking, "With all these warnings, why would anyone WANT to do this?"
Many say they want the challenge and like the comradery, not to mention the fact that the training will get you in killer shape.
Paul Solomon of Limerick, Pa. has lost 30 pounds in 3 months. He says he's stronger and more confident, among other benefits.
"I mean, I was about to go on blood pressure medication," he told me. "My blood pressure is normal now. Able to have energy to play with my kids, so it's an emotional, physical, mental change. Tighter, leaner, stronger, definitely healthier."
The team members say they are ready for the race. The Tough Mudder they are doing is this weekend in the Poconos.
There are other mud runs, some that are shorter and a little less intense. But it is important before you sign up to know what you are getting yourself into so you can prepare yourself.
