The Houston Marathon is on Sunday, with thousands of runners ready to do their utmost and push their bodies to the limit to get a personal best.

Unfortunately for spectators, sometimes that means having to view some kinda disgusting stuff. Marathoners, apparently, can get in such a zone they ignore all the signals their body is sending them to take a break.

Here are five examples. Fair warning: These include some stuff you'd rather not see. So think before you click. 5. Bleeding nipples They can make strong men cry. And everyone else cringe.

4. Peeing We guess if you've told yourself you're not going to stop and use a porta-potty, it's probably a good idea to just let it go through the shorts as opposed to taking them down. Although why she just didn't let fly while she was still running, we'll never know. It would be like the marathoner's version of tubing on the Guadalupe.

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3. Vomit This one we can understand. Although maybe we can't understand doing it so publicly. And we can only assume carbo-loading is the reason for the nuclear-yellow tint of what's coming out of the mouth.

2. Blood So she scraped her knee, what's the big deal? Well, actually, this is a somewhat famous picture of Uta Pippig, and she is winning a race despite having a quite flowing period going on at the time. If you want to look closely at the crotch, you can see.

(Last warning: Make sure you want to click to the next page.) 1. Poop Yes, yes, everyone poops. But usually not a) down their leg, b) in public, c) when toilet facilities are likely available not all that far away.