Runner’s Stomach: What It Is, What Causes It + 4 Tips To Prevent It

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Any type of gastrointestinal symptom can cause a surprising degree of interference when you run. Whether you are nauseous, gassy, or have diarrhea or constipation, if your GI system is causing some sort of detectable symptom, it can throw your workout off.

Runner’s stomach is a common issue that causes problems such as bloating, nausea, diarrhea, and stomach cramps when running.

But what is runner‘s stomach? What causes stomach cramps while running? How do you prevent stomach pain after running?

In this article, we will discuss runner’s stomach, the causes of cramps when running in stomach, and ways to prevent stomach cramps while running or stomach pain after running.

We will cover: 

  • What Is Runner’s Stomach?
  • What Causes Stomach Cramps When Running or Stomach Pain After Running? 
  • Tips For Preventing Runner’s Stomach

Let’s dive in! 

A runner holding their stomach in pain.

What Is Runner’s Stomach? 

Runner’s stomach may also be referred to as runner’s belly, runner’s tummy, and runner’s trots

It is a loose term that describes various gastrointestinal symptoms while running, such as abdominal cramping, nausea, diarrhea, gas, bloating, the urgency to use the bathroom, belching, and side stitches. You may also experience stomach pain after running.

Experts suggest that runner’s stomach can be caused by the actual jostling and mechanics of the running motion, as well as dietary, hydration, training, and hormonal factors.

Studies have found that up to 83% of marathon runners complain about various GI symptoms associated with their running, including runner’s belly or runner’s stomach, stomach pain after running, and cramps in the stomach while running.

A runner holding their stomach in pain, doubled over.

What Causes Stomach Cramps When Running or Stomach Pain After Running? 

There are various causes of runner’s stomach and cramps when running in the stomach, including the following:

  • Not waiting long enough after eating to go running can cause cramps in the stomach when running.
  • Dehydration and drinking water too quickly can cause stomach bloating when running.
  • Eating fatty foods, high-fibrous foods, and high-protein pre-run snacks and meals can delay gastric emptying and can increase bloating when running.
  • Running too fast.
A runner holding their runner's stomach in pain.

Tips For Preventing Runner’s Stomach

Here are some tips for preventing running stomach issues:

#1: Eliminate Foods That Cause Bloating

Many runners suffer from runner’s stomach or stomach pain after running if they’re eating foods before running that cause bloating.

There isn’t a definitive list of foods that cause bloating for all people.

Depending on your digestive system and personal sensitivities, certain foods may trigger bloating more than others.

For example, if you have lactose intolerance, any dairy products can cause a buildup of gas in your intestines and colon, causing abdominal bloating.

High-fiber foods such as fruits, nuts, and vegetables.

With that said, there are certain foods that tend to increase gas production for most people, such as foods high in fiber, sugar, or sugar alcohols, and foods high in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs), such as onions, garlic, and cauliflower. 

These foods can increase fermentation by the bacteria in your gut, which leads to excessive gas production that will get trapped in your stomach and intestines.

Carbonated beverages, such as soda, seltzer, and beer, contain gaseous carbon dioxide, so drinking any carbonated beverage, especially if you drink it quickly, can lead to temporary belly bloating. 

Chewing gum can also increase bloating because it causes you to swallow more air, which ends up getting trapped in your digestive tract.

In terms of bloating caused by water retention, salty foods such as chips, pretzels, deli meats and processed meats, canned soups, most sauces and condiments, fast food and restaurant dishes, frozen entrées, and pickles, can cause your body to hold onto more water, which can fill your abdomen and result in a distended stomach.

A woman holding a water bottle.

#2: Rethink Your Hydration

Many people get stomach cramps while running because they are dehydrated or they drink plain water too quickly, which results in the water sloshing around in your stomach as you run.

In order to prevent cramps in the stomach while running or stomach pain after running, you need to dial in your hydration needs.

If you’re a heavy sweater, you’re probably all too familiar with soaking through your workout clothes, even though you might be in great shape.

You should determine your sweat rate by weighing yourself before and after a run with no clothes on and then taking the fluid loss as the amount of water weight you lost in sweat during the run. 

The reason it is important to take your clothes off is that after your workout if you do not remove your sweaty clothes, you will not be able to accurately assess how much fluid weight was lost. 

You also need to weigh yourself without clothes before the run so to keep the conditions balanced.

For example, imagine that you go for a 60-minute run. Before the run, you weigh 165 pounds (75 kg). After the run, you weigh 164 pounds (74.5 kg).

This means that you have lost 1 pound, or 16 ounces, during your 60-minute run.

A runner sweating and hydrating with a sports drink.

Therefore, in the environmental conditions that you were running in, your sweat rate is about 16 ounces per hour, which means that you will need to be taking in that much fluid as you run.

Keep in mind that this method entails not drinking any fluid during your workout. This can be contraindicated in certain circumstances, such as during long workouts and when exercising in the heat. 

Alternatively, you can consume fluid during the workout, but you will need to be meticulous about measuring the number of ounces of fluid weight you drink so that you can subtract the weight of that liquid volume after your workout.

For example, you can drink 8 ounces, 16 ounces, or even 32 ounces of fluid during your workout and then just subtract that liquid weight from your final weight to determine how much sweat you actually lost.

In our example, if our 165-pound runner had hydrated with 16 ounces of fluid during her run, Her pre-run weight and post-run weight would have been the same, indicating that she hydrated perfectly and that her sweat rate is still the same 16 ounces per hour. 

A runner sweating.

During exercise, it is usually best to take in fluid periodically and gradually so that you do not overload your system with water all at once, which can lead to uncomfortable bloating and sloshing in your stomach, and can decrease the absorption rate of your fluids.

Therefore, a good hydration strategy in terms of the fluid portion of hydration needed during exercise should be planned out. For our example subject, they would need to drink about 4 ounces of water every 15 minutes during the run. 

On hotter days, this should be adjusted up to 6 ounces or so, depending on the temperature difference between the two conditions.

Consider adding electrolytes and glucose to your water, particularly if your workout exceeds 90 minutes. 

Studies have shown that drinking plain water causes people to feel more bloating compared to drinking electrolyte- or carbohydrate-infused beverages.

Plus, there is a large body of evidence that has found that sports drinks that combine carbohydrates (particularly glucose and fructose) with electrolytes can improve athletic performance by optimizing the absorption of water and electrolytes and maintaining metabolism.

According to research, the ideal concentration of carbohydrates in these electrolyte drinks is 6-8%, with an overall goal of ingesting 30–80 grams of carbohydrates per hour for workouts lasting over 90 minutes.

A piece of toast with jelly.

#3: Wait Long Enough After Eating to Run

It’s common to get stomach cramps while running if you go running too soon after eating. 

Plan to wait about 3-4 hours to run after eating a large meal, 2-3 hours for a small meal, and 1-2 hours after most snacks unless it’s a very small snack consisting of only simple carbohydrates and you’re doing a very low-intensity, slow recovery run.

#4: Slow Your Breathing

Consider a 3:2 breathing pattern, and make sure you are taking slow, deep belly breaths while running.

This involves inhaling for a count of three steps and exhaling for a count of two, so you should inhale for three-foot strikes and exhale for two strikes.

Overall, digestive distress is quite common during running, and you may deal with cramps in the stomach while running or stomach pain after running due to issues with the timing and choices of foods that you eat before and during running, your hydration strategy, and the pacing of your runs and breathing patterns.

Identifying the likely causes of your stomach cramps while running will help you most successfully target the issue and make necessary corrections to your dietary and training strategies to prevent stomach issues while running.

For a list of some great pre-run snacks that may help relieve some of your discomforts, check out our article: What To Eat Before Running, for more information.

A bowl of granola and a glass of orange juice.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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