I remember when I was in 4th or 5th grade and I would always play on my parents treadmill. On my 10th birthday I had some kids over and I had to prove how much more of a badass I could be by running on the treadmill at full speed. It worked its way up to full speed and I put my foot to the mat. My foot was immediately pulled out from under me and my forehead hit the guard bar hard as fuck. I can't clearly remember what happened after. The only thing I can really remember were all the kids screaming at me with faces of disgust and fear. The bar split the left side of my forehead open and left a huge gash. My mom recalls me trying to get up and ask the other kids what was wrong. She said the children pushed each other trying to run away from me, and that one girl started to cry because she was so frightened. I spent my birthday night in the hospital and got a present of 8 stitches.

TL;DR Treadmills can fuck you up.