The good news is that many of these “pit stops” during a marathon or half-marathon can be avoided. The digestive system can be trained as well, and, just as with pace, hydration, or fueling strategy, it pays to arrive on race day with the groundwork already done.
That said: there is no formula that guarantees you won’t have to stop. Nerves, heat, the intensity of the effort, or simply our body’s needs can play a role. The goal is to reduce the chances and, above all, to avoid mistakes that increase the risk of gastrointestinal discomfort.
Key steps to reach the start line with a calm stomach
1. Don’t experiment with food before the race
The first rule is simple: race day isn’t the time to test new foods. In the weeks leading up to the event you can experiment with different breakfasts and meals to discover what you tolerate best before running. The idea is to arrive at the competition with a routine you already know.
In the days preceding, especially for a marathon or a long event, opt for familiar foods that you know sit well with you. Some people have trouble with very fatty meals, very spicy dishes, or particularly high-fiber foods, while others may notice discomfort after consuming certain dairy products or foods they don’t tolerate well.
There isn’t a universal list of foods that are off-limits: what works for one runner can be terrible for another. That’s why keeping a small log during training is so useful: what you’ve eaten, at what time, what you’ve drunk, and how your stomach responded during the run.
2. Mind restaurant meals
Traveling to a marathon, half-marathon, or mountain race is part of the experience, but it can also disrupt routines. Eating out means you have less control over portions, ingredients, and preparation. A seemingly harmless sauce, an excess of fat, or a portion that’s too large can become a problem several hours later. If you’re competing away from home, try to keep your eating as close as possible to what you do during long training runs.
A practical option is to buy simple foods at a supermarket and prepare your own meal. It won’t be the most memorable dinner of the trip, but it doesn’t have to be. The goal is to reach the start with good sensations.
3. Plan in advance what you’ll eat
Improvisation is one of the great enemies of a runner’s stomach. And not just to avoid testing new shoes or socks on race day. If you have to travel to the event, think ahead about what you’ll eat the night before and what you’ll have for breakfast. If you’re traveling by car, you can even bring along foods you know work. You don’t need to complicate things: a simple carbohydrate-based meal with a moderate amount of protein can be enough, as long as it’s something you’ve tried before.
And remember that you don’t need to eat exactly what another runner eats. Your teammate might have oats and fruit and feel fine, while that combination could send you rushing to the bathroom.
4. Give breakfast time to do its job
One of the most common mistakes is to have breakfast too close to the start. For many runners, having breakfast about three hours before the race gives enough time for digestion and, above all, a bathroom visit before the start. It doesn’t mean three hours is a universal rule for everyone. You should adapt the timing to what you’ve learned in training. The important thing is to avoid arriving at the start line after a heavy meal just minutes before.
And if you’re one of those who drinks coffee in the morning to activate the gut, don’t start this habit on race day either. If you know it works for you, incorporate it into your normal routine and give yourself ample time before starting.
5. Train the digestive system as well
When we talk about training for a race, we often think of legs, heart, and lungs. But the digestive system also needs to get used to the effort. During long runs, practice exactly the fueling and hydration strategy you want to use in competition. Try gels, electrolyte drinks, bars, or any other product you’ll be carrying. This is especially important in marathons, ultras, and other long-duration events.
If something causes discomfort at kilometer 25 in a training run, it’s better to discover it then than during the race you’ve spent months preparing for.
6. Drink regularly, not all at once
Hydration is essential, but drinking too much at once can become a problem. Instead of waiting until you’re very thirsty and then gulping a large amount of liquid, try to spread your intake regularly according to your needs and the race conditions. Drinking too much can increase the sense of movement in the stomach and, under certain circumstances, promote gastrointestinal discomfort.
The right strategy depends on factors such as the event duration, heat, intensity, and your own sweat rate. Again, the solution is to practice it during training.
7. Bring your own fueling strategy
Aid stations are essential, but if you have a delicate stomach it’s wise to know exactly what you’ll consume. Whenever possible, bring along the products you’ve already tested during training. This reduces the uncertainty about how your body will respond.
This doesn’t mean you should automatically reject everything offered by the organizers. If you run out of fuel during the race, eating or drinking can be far more important than stubbornly sticking to a perfect plan. The key is planning: calculate what you need and carry a small safety margin.
8. The golden rule: nothing new on race day
New shoes, new gels, a new breakfast, a new drink… a bad combination. Race day should be the moment to execute a plan you’ve already rehearsed, not to experiment. The rule applies to both fueling and equipment. The fewer unknowns, the fewer surprises you’ll face.
9. Nerves can also affect the gut
It’s not all about what you eat. Pre-competition nerves can have a very real effect on the digestive tract. It’s quite common to feel an increased urge to use the bathroom before an important race. The explanation makes sense: the intestine and the nervous system are closely linked. When we’re stressed, our body can alter gastrointestinal activity. That’s why reducing stress is also part of the strategy to avoid intestinal problems.
To reduce competition-related stress, the first step is arriving with enough margin at the start. It isn’t a good idea to land in an unfamiliar city, search for the hotel, pick up the bib, and then run the next day without leaving any room for the unexpected.
Another helpful point is studying the course. Knowing the circuit reduces uncertainty. Check where the aid stations are, where the bathrooms are, and what the route is like. If during the race you feel the need to stop, knowing there’s a bathroom a few hundred meters ahead can prevent you from panicking.
Prepare everything the night before. A basic tip. Bib, shoes, clothing, fueling, hydration, documentation, transport… and the essentials. Having it all ready before you go to bed prevents morning rushes and frees mental space for what’s truly important: running.
10. Respect your usual routine
If you normally go to the bathroom as soon as you wake up, try to maintain that routine on race day. Your body runs on specific schedules and habits. Changing them abruptly can contribute to your gut behaving differently.
That’s why it’s useful to rehearse the race-day routine during long training runs: waking up at a similar time, having breakfast, having coffee if you usually do, going to the bathroom, warming up, and starting to run. The more familiar the morning of the race, the fewer surprises you’ll face.
11. Don’t obsess about avoiding the bathroom
One last important point: having to stop doesn’t mean you’ve done something wrong. Even with perfect planning, an urgent need can arise. Heat, stress, intensity, a meal you normally tolerate, or simply the day’s circumstances can change things. Therefore, although it’s useful to know where the bathrooms are along the route, you shouldn’t turn the strategy into an obsession.
In fact, trying to tolerate an urgent need for too long can make the experience much more unpleasant. If you need to stop, you stop. A quick visit to the bathroom is preferable to running with pain or discomfort.