Scrapes and bruises aside, mud run competitions can expose your body to bacterial infections, deadly injuries, and other unsuspecting dangers
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You may think you're hardcore enough for a Tough Mudder, and maybe you could manage to make it through a mud run course mostly unscathed, but there are other dangers out there on the course that could put your health-and even your life-at stake.

"Every race is different, so it's almost impossible to predict what the risks of each course are going to be," says Scott Youngquist, M.D., associate professor of emergency medicine at the University of Utah. Besides the inveitable wounds from scaling walls and army-crawling through coffin-sized quarters, incidents of flesh-eating bacteria, serious stomach viruses, and deadly accidents have cost competitors much more than their pride long after they've completed the course.

Still, participation in muddy adventure races is on the rise. The number of people who've signed up for these races has skyrocketed 211 percent in the past five years, according to the Outdoor Industry Association. To date, two million people have participated in Tough Mudders and there are countless similar off-brand competitions held across the globe each year.

While you may be prepared to face obstacles such as the Cry Baby, Dead Ringer, and the Mud Mile, here are six threats we hope you never have to navigate, but other mudders, unfortunately, have.


In 2012, 22 participants at a Tough Mudder race in Nevada contracted Campylobacter coli (C. coli), a bacteria that causes severe diarrhea, nausea, vomiting, and abdominal cramping that can last up to a week. The outbreak even lead to a Centers for Disease Control and Prevention (CDC) investigation to identify the source of the illness: mud contaminated with cattle and swine feces from nearby farm runoff. In addition to the Nevada race, C. coli outbreaks have occurred during mountain biking races in recent years when cyclists inadvertantly swallowed mud that splashed their faces en route. And that's the thing about the bacteria-it doesn't take much to make you sick, Youngquist says. Swallowing a tiny amount that gets on your face and lips is enough to cause symptoms, but it can take two to five days after being exposed to the organism before you get sick. And even if there aren't any animal farms near your course, the mud can still be contaminated with bacteria from decomposing plants and animals, Youngquist adds.


Just last month in France, more than 1,000 people came down with symptoms of norovirus, including diarrhea, vomiting, and fever, shortly after a mud run event. "The virus is transferred from person to person, but it takes microscopic amounts found in vomit or diarrhea to make you sick," Youngquist says. In other words, if someone gets sick on the course, mud that you come into contact with may be contaminated with their fluids and make you sick too. Like campylobacter, it can take a few days after exposure to the virus for symptoms to appear.

Flesh-eating bacteria

As anyone who's completed a mud run can attest to, it's nearly impossible to make it through the course without being covered in nicks and scratches. But those wounds can have serious consequences: A woman in Texas lost sight in one eye following a mud run this year. Experts believe that debris from the course cut her eyeball, which allowed flesh-eating bacteria to make its way in and destroy her cornea. "Bacteria in the mud or on your skin-such as staph and strep-can get into a cut and cause an infection," Youngquist says. Unfortunately, there's not much you can do to avoid it, though wearing pants and a shirt with sleeves can provide an extra layer of protection for your skin, says Reshma Patel, M.D., an emergency medicine physician at New York University Langone Medical Center. (Scary, right? Avoid other infections by learning the Eye Care Mistakes You Don't Know You're Making.)

Broken neck

Sadly, people have been paralyzed and killed after breaking their neck during mud runs. In 2013, a man lost his life during a West Virgina race after jumping 15 feet into freezing, muddy water. "If you jump or dive into water and can't see how deep it is, you could end up with fractures or a broken neck," Youngquist says. Courses are often jam-packed, so you also risk having other people land on your head. "Part of the appeal of these races is the sense of danger and chaos, but there's a price to pay for being the first one into a certain obstacle and finding out that it's more dangerous than you thought," he adds.


This bacteria is found in animal urine and can survive in water and soil for weeks or even months, according to the CDC. "You can get it from swallowing contaminated water or the bacteria can enter through a cut or scratch in the skin," Patel says. If infected, you can develop fever, chills, vomiting, diarrhea, abdominal pain, or skin rash.


"A lot of people sign up for mud runs because it seems like fun, but then they get to the course and discover how challenging it is," Patel says. If you haven't been exercising regularly and exhaust yourself on one of these courses, you could set yourself up for a dangerous condition called rhabdomyolosis. "Rhabdomyolosis occurs when you get traumatic breakdown of your muscles at the cellular level," Dr. Patel says. You may experience severe weakness, muscle stiffness, tenderness, or bloody urine. If you notice any of these signs-especially red or brownish colored urine or extreme muscle soreness that seems much worse than what you'd expect after a tough workout-seek medical treatment right away. Untreated, it could lead to permanent kidney damage. (But if you still want to sign up, here are 3 Exercises to Help Train for a Mud Run.)