Why Running Sometimes Makes You Shit Blood

Today’s column is about bloody shits.

What do you picture when you think of a runner? Shirtless white men, trotting down the exhaust-choked sidewalks of busy streets, looking like jaunty, tan crepes? Or maybe you see a virtuous sort, full of the kind of piety that only chia pudding and daily meditation and predawn runs can bestow? I used to think of my grandpa, an early adopter of the new jogging trend in the 1960s. He was covered by the local paper after alarming residents with his seemingly compulsive mobility. And sure, sometimes I think about my own attempts at becoming A Runner, the way I assume some people long to become monks. But now, thanks to the wonders of the internet, when I think about running, I think about bloody shits.

Running has a lot to do with pooping, but we don’t usually talk about it. All that blood, sequestered away from the colon, available for use in the muscles; all the mechanical jostling of the bowel: these things can change a person’s plans, if you know what I mean. In a study of 109 distance runners, 62 percent of them reported they’d had to stop and take a mid-training shit; 12 percent had shit themselves while still running. Not only that, but nearly half had diarrhea after a race or grueling workout, with 16 percent of the total group reporting they’d shit blood after a hard run.

I don’t know about you, but when I fantasize about what my life would look like were I the kind of woman with nice leggings and a golden retriever that needs running at precisely 6:00 a.m. every morning, I don’t think about the stark reality of shitting blood in suburban bushes sans toilet paper. But perhaps that just goes to show my ignorance.

This all started because I stumbled across an Ask the Coaches column at Runner’s World from 2006, titled “Rectal Bleeding.” In the answer, Dr. Cathy Fieseler stated that “blood in the stool following a strenuous workout or race is fairly common.” I’m not sure why I, a non-runner with bad knees, was toodling around that particular website; the point is that the doctor writing the advice column seemed pretty relaxed about runners shitting blood and that brought up some questions for me. The reader’s query, in full:

“Q: Rectal Bleeding: I started running this year, I am 44 years old and when I started increasing my running to run a Half Marathon I started having rectal bleeding. I have been scoped and nothing was found. How common is this and will this go away. Help! This gets in the way of my running!

—Thanks Kellie”

Help! This gets in the way of my running! begs an entirely different set of questions, namely philosophical ones regarding how much a person needs love something for shitting blood to not deter, but we are here to talk about physical shit, not metaphorical, so put a pin in that.

The doctor responding to Kellie’s query is glad she’s had a negative scope and assures her that while rectal bleeding is always a concern, her plight is a common occurrence. The likely culprits, she notes, are the usual suspects: lack of blood flow to the bowel and the pavement pounding rhythms that shake loose the precious cargo of the gut. (It could also be hemorrhoids or rectal fissures.) Advice was dispensed (stay hydrated and be aware that anti-inflammatory medicines like ibuprofen and aspirin can increase bleeding), and the whole column wraps up on a fairly positive note: If it’s exercised-induced ischemic colitis, the problem should get better as Kellie’s body gets used to longer runs.

I, on the other hand, still had many questions. Namely: how, exactly, can running make you shit blood?

The answer starts with ischemia. In simple terms, ischemia happens when a part of the body isn’t getting enough blood. We commonly talk about it in terms of myocardial ischemia, when blood flow to the heart is reduced, starving it of oxygen. This is also called a heart attack. But it can happen elsewhere, and anytime part of the ol’ meat sack isn’t getting enough oxygen and glucose, there will be consequences.

The bowels of the human body are a needful, sensitive thing. Normally, the colon receives anywhere from 10 to 35 percent of total cardiac output; this means that every time your heart pumps, one-tenth to one-third of the blood goes south to do the job of nourishing the colon and ultimately participate in the transport of nutrients away from the digestive organ.

The arteries that feed the colon are very sensitive too, especially to vasoconstriction. Researchers believe that this attuned ability to quickly decrease blood flow to the colon is an evolutionary adaptation to send blood to the brain and heart in times of stress, like running from a lion.

Or for pleasure. Or pain. Or some combination of the two.

Here’s the rub: If blood flow to the colon drops by half, we are now in the territory of ischemic colitis. When this happens, there can be hemorrhaging and swelling, with a side of premature cell death and/or ulceration, literal bits of you washing off into a swamp of shit, dying as they scream for oxygen. Certain parts of the colon are more predisposed to suffering these effects. Called the “watershed” areas, these are weak points because they get less blood than the rest of the colon, thanks to their proximity to vascularization.

What could possibly cause blood flow to the colon to drop by half?

Picture again, the runner. Legs pumping, arms swinging, breathing like a laboring sheep. With each step, their body is a piston-cum-shock absorber, propelling them through space and time, sweat creeping onto and off of their skin. Normally pressed to howl in need, their muscles swell and demand, lungs working overtime to oxygenate enough blood to pass around the body. The struggle repeats itself, over and over and over, to meet this new set of needs. Sorry colon, the threat we run from is real, and you, sweet friend, must make a gentle sacrifice today. It may not be a lion at our backs; perhaps it’s the looming threat of financial crisis, or a bad date last night, or just the desperate need to indulge in some euphoric masochism to get through another fucking day. Either way.

Help! This gets in the way of my running! The runner, wincing at the tarry mess in the toilet. It’s a watershed moment, the first time you shit blood for something you love.

Do you have questions about sports-related bodily horror? Want the inside scoop on how a particularly gruesome femur break went down or the intimate details of sharing skin fungi? Email our columnist.

Leigh Cowart is a freelance writer whose work has appeared in The Washington Post, The Daily Beast and Hazlitt, among others. Follow her on Twitter @voraciousbrain. Careful, she bites.