The Bank of America Chicago Marathon steps off from Grant Park on Sunday, October 11 — pro field at 7:30 a.m., first wave five minutes later, tens of thousands of runners behind them. If you're racing it, your legs are basically built by now. The taper is about not ruining them.
Your gut is another story. Nobody writes "stomach" into a training log, and yet ask any marathoner what they fear more at mile 18 — their quads or their intestines — and you'll get a nervous laugh. Runner's trots are common enough to have their own name, and the fall racing block (Chicago now, New York next month) is when thousands of people discover them at the worst possible moment.
Why 26.2 miles is so hard on a stomach
A few things gang up on you during a marathon:
Blood leaves the gut. During hard running, your body shunts blood toward working muscles and skin. The digestive tract gets less of it, and an under-perfused gut gets irritable — cramping, urgency, sometimes diarrhea.
Everything is bouncing. Two-plus hours of mechanical jostling keeps contents moving whether you'd scheduled that or not.
Race fuel is concentrated sugar. Gels and sports drink are easy calories, but in a stressed gut they pull water into the intestine. That's the classic recipe for an emergency porta-potty stop.
Nerves. Race-morning adrenaline speeds the gut up all on its own, which is why the start-corral bathroom lines are the longest in Chicago.
What any of this has to do with hemorrhoids
More than you'd think. Hemorrhoids are swollen veins in the anal canal, and race season hits them from four directions at once. Urgent, repeated bowel movements irritate the canal directly, and the hurried cleanup afterward chafes skin that's already inflamed. Dehydration — easy to do over 26.2 miles, even with every aid station — firms up stool for the next day or two, which means more straining. Straining in a porta-potty with a corral closing in ten minutes is exactly the bearing-down that flares things. And getting to Chicago at all usually means hours of sitting in a plane or car seat, which lets blood pool in the veins you're about to spend three to five hours pounding.
None of this means runners are doomed to hemorrhoids. It means race week is a week to be deliberate.
The nine-day plan
Now through about three days out
Keep your fiber and water steady — this is not the week to start a new supplement, a new restaurant streak, or a gut-health protocol you saw online.
Practice your race fueling on your last short runs if you haven't. Race day is a terrible day for a first date with a new gel.
Cut back nothing abruptly. Sudden diet changes in either direction tend to show up as constipation or urgency 48 hours later.
Travel day
Drink water like it's a job. Cabin air and road-trip snacking both dry you out.
Get up and move every hour or so if you're flying or driving — your training plan already told you not to sit all day, and your veins agree.
Pack your own familiar breakfast for race morning instead of gambling on what the hotel has.
The day before
Eat your bigger meal at lunch, keep dinner simpler and lower-fiber than usual, and stop experimenting entirely. Plain is fast.
Skip the second beer. Alcohol dehydrates and irritates on both ends of the race.
Race morning
Wake up early enough to eat, have coffee if coffee is part of your routine, and give your gut a real chance at a complete bathroom trip at the hotel, where you're not racing a corral cutoff. An unhurried bathroom visit beats a strained one every time.
Don't force it. If it's not happening, straining for ten minutes before a marathon is worse than lining up as-is.
After the race
Rehydrate steadily through the afternoon, then return to normal fiber by dinner. The post-race day or two is when hard, dehydrated stool shows up.
You will be sitting a lot — flights home, celebratory dinners. Keep taking the walk breaks.
If a flare shows up anyway
Sometimes you do everything right and the combination of effort, dehydration, and urgency wins anyway. The playbook is short. A warm sitz bath soak for 10–15 minutes once or twice a day calms irritated tissue — a hotel bathtub works fine. Swap dry-paper scrubbing for a gentler routine with a hygienic cleansing lotion, because post-race cleanup on chafed skin is half the misery. And for the pain and swelling itself, an advanced hemorrhoid cream with lidocaine and phenylephrine offers temporary relief of symptoms while water, fiber, and a few days of not running 26.2 miles do the actual work.
See a doctor if you have bleeding beyond streaks on the paper, severe or worsening pain, a hard and very painful lump, or a flare that's still going after two weeks. And race-day details — start times, waves, the expo schedule — are all in NBC Chicago's race-weekend guide.
Run well. May your splits be even and your porta-potty stops be zero.
This article is for informational purposes only and is not medical advice. Talk to a healthcare provider about any persistent or concerning symptoms.