Medical experts are alarmed at the injuries arising from the growing popularity of Tough Mudder races. Over three years, the event has expanded to 35 locations and 750,000 participants worldwide, which means an untold number of serious injuries.

These endurance races are known to be particularly grueling. Participants must complete a 10- to 12-mile course that consists of up to 30 military-style obstacles. The Electric Eel is one common obstacle that forces people to slide on their bellies through frigid water with live wires just above their heads, threatening to inflict what The Tough Mudder organization describes as a “brain reboot,” or 10,000 volts of electricity, if someone doesn’t remain close to the ground.

Last April, the race experienced its first death when a 28-year-old participant drowned while attempting Walk the Plank at the Mid-Atlantic Tough Mudder. The obstacle required racers to jump down 15 feet into a 12-foot-deep pool of cold, muddy water.

In a recent study, doctors from Lehigh Valley Hospital and Health Network in Allentown, Pennsylvania, reported the diverse cases that a single Pennsylvania hospital saw after a two-day long Tough Mudder event last June.

In their study, lead author, Marna Rayl Greenberg, and colleagues, reported that the burden on emergency medical personnel during this event was unexpected, as more than 100 advanced life support responses were activated.

"No training on earth can adequately prepare participants for elements such as jumping from a nine-foot height or running through a field of electrical wires while wet and hot," said Greenberg in a statement. "The volume and severity of injuries in the Tough Mudder race we studied was unusually high, possibly leading to some permanent disabilities. The 1.5 million people who are predicted to enter obstacle races like this in the next year should be well aware of the risks they are taking."

In their study, Greenberg and her team focused on five of 38 patients who were treated at the local emergency department for event-related injuries. One of the patients had received 13 electrical shocks in just the last obstacle of the race, which produced burn marks and inflammation of the heart muscle.

Another patient suffered from fainting and “altered mental status” after receiving multiple electrical shocks to the head while running through water.

A third patient completed 20 of 22 obstacles only to endure seizure-like activity and an altered mental status, as well as an inability to move the entire right side of his body. After treatment at the emergency department, he was admitted to the intensive care unit with a diagnosed form of paralysis. After six months he still has lower right leg disability.

This sudden influx of extreme injuries prompted the authors to issue a note of caution to any hospital that happens to be in the vicinity of these type extreme sport events.

"In the past few years, obstacle racing has experienced a rate of growth that may be unprecedented in the history of participatory sports," said Dr. Greenberg. "Organizers, participants, and local emergency services need to be prepared for a large number of diverse injuries at Tough Mudder and other similar obstacle races."

The medical experts are doubtful that anyone can really prepare for this kind of sport. "In some of these endurance events, effective training may prevent problems such as dehydration or rhabdomyolysis," the authors note in their study, "but it is doubtful that training will enhance performance or prevent injury in an event in which obstacles include having to jump off a nine-foot height or run through a field of electrical wires."

Source: Greenberg M, Kim P, Duprey R, et al. Unique Obstacle Race Injuries at an Extreme Sports Event: A Case Series. Annals of Emergency Medicine. 2013.