I was closing in on seven hours in the saddle, churning up the final 10-percent grade on the interminably long, high-elevation Trout Creek climb at SBT GRVL, 102 miles into a 140-mile day when I got the red light from the engine room.

We’re shutting down for the day. Might as well keep those bars in your pocket. We’ll send them right back up if you try to shove them in here.

Wait. What? No! I have forty miles to go! You can’t shut down now.

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Well, you should have thought about that before you stop, dropped, and rolled in this high, dry, thin air, neglecting to maintain your hydration plan on this 80-degree day and pushing into the red so long we couldn’t work down here.

Fair enough! I’ll put a foot down at the next aid station and give you what we need so we can carry on.

And I did. I stopped, hydrated, literally cooled my jets with a bottle of water over my head, and was able to stuff down—and keep down—a few sandwich squares to keep on rolling for a respectable finish.

But when it comes to gut health and performance, this is really just the beginning. As endurance athletes we tend to obsess over the fuel we take in, but we don’t pay enough attention to the engine that turns the food we eat into the energy we need to power the pedals.

That’s a problem. Because if your gut isn’t working, neither are you. And we endurance athletes use and abuse our guts more than the average human—maybe even more than our human body was designed to do, says Boulder, Colorado-based sports physiologist and cycling coach Allen Lim, Ph.D.

“We’re designed to ‘rest and digest.’ We’re not really built to take in and digest a bunch of food while racing hundreds of miles, so our guts take a pummeling when we do. And when they fail, we start to fail, too,” he says.

And that’s not just during exercise. Our energy, physical function, immunity, even our moods are at least partly regulated by how healthy (or not) our gut is. Here’s how to take care of yours, on and off the bike.

Eat On the Go

Research shows that endurance athletes who aren’t accustomed to eating and drinking during exercise have twice the risk of developing GI symptoms than those who are accustomed to taking in food and drink on the move.

“Your gut can be conditioned to reduce GI distress during exercise,” says Leslie Bonci, M.P.H., R.D., sports nutritionist at the Pittsburgh-based company Active Eating Advice. “But you have to train it.”

“[Your digestive system] can acclimate to activity and become better able to tolerate fluid, carbohydrate, even protein and fat for longer-duration activity with less discomfort,” she says. As a bonus, you’ll be able to deliver more much-needed nutrients to your working muscles.

That means eating and drinking during training rides exactly how you would in an event—at a steady rate while riding at or near race pace, without stopping to allow your body to rest and digest.

Keep Blood Volume High

During exercise, blood shuttles away from your gut and into your muscles and lungs. By the time you’re hammering at your max, blood flow to your gut plummets by 80 percent, so your digestive system is already pretty compromised. If you allow yourself to get dehydrated, blood volume diminishes, so there’s even less to go around, and your gut is further strained. Keep your blood volume high by drinking about one bottle of fluid per hour (more in the heat) while you’re out there.

Keep Your Cool

It’s harder to keep your gut happy in the heat. “Your body temperature really matters,” Lim says. “If it drifts too high too long, you’ll suffer a lot of negative consequences and one of the first is GI distress, because if your body gets too hot, the integrity of your small intestine begins to fail.”

So again, stay hydrated. Drink something ice cold if possible, because it creates a heat sink and helps cool your core temperature. And look for ways to keep yourself cool during long events, such as cold towels, sponges, or dumping cold water over your head.

Prevent Leaky Gut

Your gut is lined with a thin mucosal barrier that works as a two-way gatekeeper, allowing you to absorb nutrients while preventing germs and undigested food particles from inside the gut to enter your bloodstream. Strenuous exercise, particularly in the heat, can make this barrier more permeable, creating a condition known as leaky gut, which allows those things that are normally blocked to pass through, leading to inflammation, digestive distress, fatigue, and other unwanted effects.

Avoiding dehydration and heat stress helps keep your gut sound. Also steer clear of non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, especially during exercise, which studies show can damage your gut.

[Want to fly up hills? Climb! gives you the workouts and mental strategies to conquer your nearest peak.]

Build Your Biome

The bacteria in your gut—your gut’s microbiome—help keep your intestinal wall strong to prevent unwanted leaks.

That microbiome also plays a major role in our overall health and endurance performance. Research shows a healthy gut biome can boost your metabolism, energy availability during exercise, and recovery after a workout.

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The good news is that athletes have a higher diversity of gut microorganisms than their sedentary peers, according to a study recently published in the journal Gut. And that rich, diverse biome is healthier. Other research has demonstrated that just six weeks of cycling three times a week reduced the number of potentially inflammation causing microbes and increased the beneficial, metabolism-enhancing microbes in a group of previously sedentary volunteers.

As athletes, we abuse our guts on a regular basis, so we need to take care of that biome to maintain its healthy diversity. Poor diversity doesn’t just sap your energy; it can also lead to depression, anxiety, and low immunity, says exercise nutritionist and physiologist Stacy Sims, Ph.D., author ROAR.

Maintain your healthy, athletic diversity by eating a wide-variety of probiotic foods such as yogurt, kefir, sauerkraut, pickles, kombucha, tempeh, and pickles, which contain bacteria, and prebiotic foods such as artichoke, garlic, onions, leeks, asparagus, and green bananas, which feed your gut bacteria.

Eating a Mediterranean diet can also help, according to new research presented at United European Gastroenterology Week 2019. The study of more than 1,400 adults found that eating a diet rich in plant-based foods, including fruits, vegetables, grains, legumes, and nuts, as well as fish was linked to a healthier gut microbiota, as well as lower levels of inflammation.

Conversely, people whose diets were rich in meat, fast food, and refined sugar had fewer good types of bacteria in their guts, as well as more intestinal inflammation.

Other studies
have found that people who drink two or more cups of coffee a day have a healthier gut biome than those who drink less or no coffee. Strong, Belgian beer is also brimming with very healthy gut-friendly bacteria, but that doesn’t mean you should guzzle either. As always, consume in moderation.

As to whether you should take probiotic supplements, the jury is still out. Research leans toward the benefits, showing that among athletes and highly active people, taking probiotics can reduce the frequency, severity, and duration of respiratory infections (common among endurance athletes, especially after hard races) and gastrointestinal illness. But at this time, nobody knows for certain which specific probiotics we should be supplementing.

“There’s been some good peer-reviewed research on probiotics like BC30 [a form of Bacillus coagulans] showing that it helps with protein absorption, immunity, and helping quell GI distress,” Lim says. “But while a healthy microbiome is important, I don’t know if we can make it up by taking one probiotic.”

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Selene Yeager
“The Fit Chick”
Selene Yeager is a top-selling professional health and fitness writer who lives what she writes as a NASM certified personal trainer, USA Cycling certified coach, Pn1 certified nutrition coach, pro licensed off road racer, and All-American Ironman triathlete.