When I think about the London Marathon next month, which will be my first marathon in nearly seven years, I’m not worried about hitting the wall, or messing up my pacing, or aggravating my chronic knee issue. Nope, my deepest fear is pooping my pants mid-race.

I have a sensitive stomach that is often aggravated by travel — and running. So the thought of combining the two makes me considerably uneasy. Turns out, I’m in good company among other fearful runners.

Stressing about digestive issues when travelling for a race is “very, very common,” according to Amity Lui, a sports dietitian who works with runners. Unfortunately, the worries are somewhat justified: About 30 to 70% of travellers experience diarrhoea, says Dr Christine Lee, a gastroenterologist. And 62% of long-distance runners reported having to stop a run due to urgent diarrhoea, according to an older survey published by Journal of Clinical Gastroenterology.

The good news: You can reduce your chances of GI issues when travelling for a race with a few simple steps. We tapped three experts for insight into why the combo of travel plus running can lead to rowdy bowels, and what you can do to minimise your risk of pre- and mid-race potty problems.

How Traveling for a Race Can Mess With Your Stomach
Between airport lines, crowded waiting areas, and unexpected delays, travelling is inherently stressful. And stress can trigger the release of the hormone adrenaline, which can cause the GI tract to hold onto everything. Then, when adrenaline subsides, people may experience the “release or overflow of what was held in,” says Lee. In other words, you have the worst of both worlds: constipation and then diarrhoea.

Additionally, the stress of being in a new environment and getting thrown off your usual routine — sleeping in a new place, not sleeping enough, eating new foods, eating out more, exercising less, etc. — can disrupt your body’s stress hormone levels, says Lee. These changes can impact your gastrointestinal system, as well as your immune system and circadian rhythm.

Layer a race on top of that, and you could get hit with “unexpected bouts of diarrhoea, sometimes urgent and hard to control, especially when the endorphins kick in,” says Lee. That’s because exercise can increase the production of endorphins, a hormone that is focused on pain relief and stress relief. The relaxing effect of endorphins can sometimes trigger the urge to poop, Lee explains. Pre-race jitters, dehydration, and eating certain foods (including new-to-you-foods), can also lead to digestive turmoil.

Quick caveat: Though travel and running are two common culprits of stomach and bowel distress, if you have GI symptoms that are new or concerning to you, see your primary care provider or a gastroenterologist, says Lee. “Not all diarrhoea or GI upsets can be generalized,” she says, and a medical professional can help you get the root of the issue.

How to Reduce Your Risk of Digestive Issues When Traveling

1. Scope Restaurants in Advance
Part of the fun of travel is trying new foods, but to spare your bowels, you’ll want to save experimentation until after the race. That’s because you could inadvertently consume a food that doesn’t jive well with your GI system, and then face the consequences during your race.

A safer bet is to stick to foods that are closer to what you regularly eat at home, especially the day before your race, says Jen Scott, a Road Runners Club of America running coach in Beaverton, Oregon.

“One thing I usually recommend — and I do it too, myself — is to look around the area that you’re staying and look at what restaurants are around and what’s available to you,” says Scott. That way, she explains, you know in advance where you’ll be able to access food that will likely sit well with your stomach.

Taking the time to plan some of your travel meals in advance can also help ease any prerace and travel anxiety, says Lui. Browse menus online and consider making advance reservations.

2. Pack Your Own Snacks
Because you won’t have access to your kitchen while travelling, it’s a good idea to pack simple-to-digest snacks in your suitcase that you know your body can tolerate well, says Scott. She recommends items like fruit and nut bars, applesauce, dried fruit, pretzels, fruit snacks, instant oatmeal, biltong, fig bars, dry cereal and crackers. These types of snacks are also good options if you’re pre-race carb loading, a recommended nutrition strategy if you’ll be racing for more than 90 minutes.

3. Hydrate, Hydrate, Hydrate
Travel, in general, can up your chances of dehydration because you’re not on your normal schedule and your access to fluids is not the same, says Scott. But aeroplane travel in particular can lead to dehydration because the cold, dry, and pressurised air in the cabin causes you to lose more fluid than normal either through your breathing or through evaporation on your skin, says Scott.

Not imbibing enough water can cause subclinical constipation, which is when your bowel movements are regular but incomplete (meaning, you don’t get everything out), says Lee, as water helps to move things along. And dehydration during an endurance race can exacerbate GI issues, says Lui.

If you’re travelling via plane, bring a large, empty water bottle in your carry-on and refill it once you’re through TSA, says Scott. Then, when you’re on the aircraft, sip an extra 250 to 350 ml per hour beyond your usual amount of water intake to combat the dehydrating effects of being on a plane.

You may also want to have a serving of a sports drink. The sodium content in those products will help your body better retain water, thus boosting your hydration, says Scott.

Though you may be tempted to order a mid-flight cocktail to help you relax en route, avoid sipping alcohol, as that will lead to dehydration, she adds.

Keep in mind: “You don’t get hydrated instantly,” says Lui, who recommends sipping fluids consistently throughout the day versus chugging an entire bottle every couple of hours. Scott suggests setting an alarm on your phone every hour or two as a reminder to drink up.

4. Stick to a Consistent Eating Schedule
Early morning flights and/or switching time zones can thrown off your sleep schedule, which can influence your ability to correctly interpret hunger cues, says Scott. “Some people will find that they’re not as hungry or they just don’t have an appetite. And then some people might find that they are hungrier, or want to eat more to try to stay awake,” she says.

Instead of relying on hunger and full cues to determine when to eat, “you’re gonna have to really force yourself to eat on a schedule before a race,” says Scott. That’s because you want to ensure your body has the energy it needs to effectively tackle the run.

If you’re not feeling as hungry as usual, try having smaller meals and frequent snacks, says Lui. The right cadence will vary person to person, but generally speaking, aim to eat a small to medium snack every one to two hours, or a larger snack every two to three hours, says Lui.

5. Strive for Solid Sleep
Speaking of sleep getting thrown off, that in itself can lead to stomach issues when travelling. “Your GI tract is greatly influenced by your hormone fluctuations and circadian rhythm,” says Lee. Combat these effects by maintaining good sleep hygiene — essentially, try to stick to your normal sleep routine, keep the temperature of the bedroom the same as what you’re used to, and block out light and noise if necessary.

If you’re adjusting to a new time zone, aim for daylight exposure, especially between the hours of 1 p.m. and 3 p.m. local time, as this can help you adjust faster, says Lee.

6. Maintain a Simple Diet
Of course, nutrition is highly personalised and what works for one runner may not settle well for another. That said, when travelling for a race, you’ll generally want to steer clear of raw foods and instead eat only cooked foods, says Scott. This will decrease your chances of getting food-borne illness, she explains.

Scott speaks from experience: Two days before running the Boston Marathon, she drank unpasteurised beet juice, which she surmises gave her food poisoning. “I ended up in a porta potty every kilometre and I ended up in the medical tent at 38K needing multiple bags of IV fluids,” she recalls. “It was horrible.”

You should also avoid high-fibre and high-fat foods, says Lui, as those can take a while to fully digest and thus could still be lingering in your system when you start running your race, causing GI issues. Sugar alcohols can also contribute to stomach problems for some, so you’ll want to carefully check the ingredient labels of any travel snacks before chowing down, says Lui.

In general, focus on foods that are easy to digest, like chicken and rice, says Scott.

7. Calm an Anxious Stomach
Your mental state can seriously impact your bowels. “Some people will get diarrhoea just because of how anxious they are and some people will lose their appetite,” says Scott. So if travel and/or race stress has your stomach in knots, stick to lighter fare – crackers, bananas, applesauce, and toast, for example – as a way to calm a swirling gut.

Additionally, ease anxiety by packing items that bring you comfort, says Lui, like your favourite running outfits or cosy lounge clothes. Carving out some time to meditate or visualise your race can also help settle your jitters.

8. Consider Bottled Water
Every area has its own natural bacteria in the water source. If you live there, your body adjusts to it, but if you’re visiting, “it might take your gut a little bit of time” to adapt, says Scott. As such, consider drinking bottled water on the days before and of your race.

9. Quash a Noisy Stomach on Race Morning
If you wake up on race day with an unsettled stomach, don’t panic. Instead, focus on hydration by drinking a sports drink (which will also provide carbs and electrolytes) and if you can, eat something simple like dry crackers, says Scott.

If you feel constipated, try sipping warm water or a cup of coffee, as both can help stimulate your bowels. If there’s still no movement, go for an easy warm-up jog. “Often just the jostling can help get things moving,” says Scott.

READ MORE ON: diarrhea pre-race runner's trots Runners stomach travel