(WXYZ) - Multiple runners who participated in the Tough Mudder at the Michigan International Speedway last weekend have fallen ill.
The Tough Mudder is a 10-12 mile obstacle course designed to test people's endurance.
The Michigan Department of Community Health confirmed that there are cases of a gastrointestinal illness, but did not confirm what the illness was yet.
The Lenawee County Health Department says they have received more than a dozen calls from participants and spectators who said they weren't feeling well.
Some symptoms reported were nausea, high temperature and diarrhea.
The MDCH's lab is testing stool samples and will have preliminary test results early to mid next week.
To report any symptoms, call the Lenawee County Health Department at 517-264-5243.