Runner’s stomach goes by several other names — runner’s tummy, runner’s trots, runner’s gut, and runner’s belly. No matter what you call it, it’s no fun.

Symptoms of abdominal cramping, the strong urge to use the bathroom, nausea, and diarrhea during a run can slow down your pace and make it hard to get through your workout.

We look at the root causes of runner’s stomach, along with treatment and prevention recommendations.

The medical literature on runner’s belly suggests that it’s caused by the mechanics of running itself, as well as dietary and hormonal factors.

When you’re running for an extended period of time, the blood flow that’s normally directed to your digestive system is diverted to your cardiovascular system.

This can disrupt and irritate your digestive process. As a result, you may feel a strong urge to expel whatever’s in your digestive system. You can even end up with symptoms of diarrhea.

While this is happening, your body is also moving up and down as you continue to run. This movement contributes to feeling like you need to use the bathroom as waste material is jostled around your intestines and your stomach acid is sloshing.

Finally, running causes the release of hormones like cortisol. These hormones can feel good when they hit, causing the familiar euphoria runners know as “runner’s high.”

But these hormones can also affect your digestive system and add to the confusion that your body feels during an endurance activity such as running.

How common is runner’s belly?

Runner’s belly is common, especially among distance runners. Researchers estimate that between 30 to 90 percent of runners and endurance sport athletes experience GI symptoms during their training and racing events.

In one study of 145 endurance runners, men experienced GI discomfort on 84 percent of training runs over the course of 30 days. Women reported symptoms 78 percent of the time.

Healthline

There’s no cure for runner’s belly, but there are several preventive steps you can take to try to minimize symptoms.

Diet

A change to your diet can enhance your performance while running. It can also lead to less discomfort during training and races.

A diet that’s low in certain sugars and carbohydrates — sometimes called a low FODMOP diet — has been shown to have a positive effect on GI tract issues while exercising. A low FODMOP diet avoids wheat and dairy, as well as artificial sweeteners, honey, and many fruits and vegetables.

You can also be mindful about when you consume your food and drinks. A review of literature shows that eating and drinking right before you exercise can cause strong abdominal pain during exercise.

Probiotics

A healthy gut and regular bowel movements can mean that you experience less digestive distress during endurance exercises.

Taking probiotic supplements can help strengthen your gut and make you less prone to bathroom runs during your training.

A 2014 study showed that 4 weeks of probiotic supplements helped improve runner’s stamina and digestion when running in high temperatures.

A similar 2019 study demonstrated that probiotics helped decrease gastrointestinal symptoms for runners during a marathon.

Hydration

Cramps, nausea, and stitches in your abdomen during running can be the result of improper hydration.

Hydration before and during a long run is important, but figuring it out can be tricky.

Drinking too much water could make cramps and digestive irritation worse. The safest bet is to develop a habit of drinking enough water regularly and using electrolyte-infused beverages right before and after your runs.

Practice

Even elite athletes who run multiple marathons every year experience runner’s belly from time to time.

Figuring out a routine that works for your system and sticking to it on your training and race days can make runner’s belly less of an obstacle for you. It might take some experimenting to get it just right, but once you find what’s working, stick to it.

Anecdotally, many runners swear by having a solid pre-race routine that involves the same pre-run snack and the same recovery foods after each event.

If you’re frequently experiencing runner’s stomach, you may have a condition that isn’t directly linked with running.

Irritable bowel syndrome (IBS) as well as celiac disease have similar symptoms to runner’s belly, but could be triggered by other factors and activities.

You should talk to your doctor if you experience any of the following symptoms:

  • episodes of diarrhea and cramping that happen more than once a week
  • frequent constipation
  • nausea, gas, and bloating regardless of whether or not you’ve been running
  • bowel movements that are often runny, or blood in your stool

Your doctor will talk to you about your symptoms to determine if what you’re experiencing is a side effect of running or a different diagnosis. They may also order a colonoscopy to rule out any other possible conditions.

Runner’s belly isn’t uncommon, and there’s no easy cure to stop it from happening.

Planning your meals, avoiding trigger foods, taking probiotics, and staying hydrated may help you improve your performance on the track while also decreasing the chances that you’ll get these symptoms.

If GI symptoms are consistently an obstacle in your runs, you should speak with your doctor to rule out other possible health conditions.