"Those 36 hours were pretty rough," Bob Krusky said. "Not really able to keep anything down."
The Tough Mudder challenge tests strength and endurance, and apparently your immune system, too.
It left a lot of people with more than just sore muscles this past weekend.
Health departments are getting reports of norovirus-like symptoms from people who braved the event at Michigan International Speedway. They're not sure how many people yet, because the calls keep coming in.
Bob Krusky is proud of his Tough Mudder battle scars. In fact, he expected to get them in the 10-mile hardcore physical challenge.
"You definitely get a little dinged up in the course, which is normal, part of the fun," Krusky said.
But what's not fun is the stomach bug he got after. Turns out the Tough Mudder was also tough on intestines. Many people are reporting vomiting, diarrhea, and cramping.
"Chills and a bit of a fever, those 36 hours were pretty rough," Krusky said. "Not really able to keep anything down."
News 10 talked with people all over the state with similar symptoms, and some even worse. One woman in Jackson stayed home from work all week, and finally went to the hospital. Her doctor told her she might have e coli. Meanwhile, we also got lots of reports of pretty gross eye infections.
The Michigan Department of Community Health and Lenawee County Health Department are taking this very seriously.
"The one thing about a gastro-intestinal illness is that it can be transmitted very easily," MDCH spokesperson Angela Minicuci said. "It can come from sharing a drink or food, or simply touching a surface that someone else may have touched, like a door handle."
In the Tough Mudder, you're literally sharing blood, sweat and tears, and maybe even more than that, with at least 15,000 people from all over Michigan and the U.S.
"You would overhear people mentioning that they had relieved themselves in the water, and that kind of stuff," Krusky said.
The health department doesn't know the source yet or how many people may be affected. In a statement, Tough Mudder told News 10 it's working closely with them to determine the cause.
At the end of the day, most people say it was worth it.
"I'd definitely sign up for it again," Krusky said.
Participants are required to sign a waiver that says they can't sue Tough Mudder for illness or injuries.
There have been reports of spectators getting sick as well.
The MDCH and Lenawee County have staff dedicated to contacting people who were at the event, and running tests to figure out the source.