“You wake up the next day and you’re like,

 “You wake up the next day and you’re like,

 what is all this on my arm? Like what is going on here? And it’s on both arms. That’s where I was digging and doing army crawls and it’s on the inside of my knees where I was pushing off of as well,” Nicole Villagran told KGO.

Tough Mudder events involve obstacle courses in which participants crawl through mud and overcome challenges such as climbing over logs or traversing rope courses.

In a statement to McClatchy News, organizers said “the health and safety of the Tough Mudder community is always our top priority” and encouraged anyone with medical concerns to contact a doctor.