Stomach Pain After Running? Here Are 12 Possible Causes + Fixes

We often think of musculoskeletal injuries like shin splints and IT band syndrome when we think of pain after running, but many runners also deal with various types of stomach pain after running. 

While not typically a running injury per se, stomach pain while running or after a workout can still significantly compromise your training as well as your comfort level for the rest of the day. 

In this guide, we will address stomach problems in runners as we look at different causes of stomach pain after running and how to prevent an upset stomach after running.

We will cover: 

  • Why Are Stomach Problems Common In Runners?
  • What Types Of Stomach Issues Are Common In Runners?
  • Stomach Pain After Running? Here Are 12 Possible Causes
  • How to Prevent Stomach Problems When You Run

Ready?

Let’s dive in!

A woman experiencing stomach pain after running.

Why Are Stomach Problems Common In Runners?

Stomach problems are a fairly common malady for runners because running can be highly disruptive to the gut and digestive system. 

The jostling motion of running, and the impact forces for each step, jiggle and stimulate the gut, often triggering contractions (peristalsis) of the smooth muscle lining the GI tract. This can contribute to diarrhea from running, often termed runner’s trots.

Moreover, when you run or engage in other forms of vigorous exercise, blood is diverted away from the digestive tract to meet the increased demand from the heart, lungs, and working muscles. 

This causes digestion to slow or nearly cease, leaving any residual food to hang around in your stomach. Therefore, if you go running after eating, undigested food in your stomach might slosh around, and the processing of it may come to a halt.

Plus, as food sits in the stomach and digestive tract, the bacteria in your gut ferment the sugars and produce gas, contributing to gas buildup and abdominal distention.

Accordingly, you can experience gas, bloating, indigestion, abdominal cramps, side stitches while running, and stomach pain after running.

A woman experiencing stomach pain while running.

What Types Of Stomach Issues Are Common In Runners?

Stomach pain after running or an upset stomach after running is often attributable to one of the following symptoms or common stomach problems for runners:

  • Stomach cramps or abdominal cramping 
  • Side stitches
  • Heartburn
  • Nausea
  • Indigestion 
  • Gas
  • Belching

Stomach Pain After Running? Here Are 12 Possible Causes 

So, why are you experiencing stomach pain after running? Below, we list the most common causes of stomach problems after running:

A woman experiencing stomach pain.

#1: Running Too Fast

The faster you run, the less blood your digestive system receives, because it is shunted more aggressively towards your skeletal muscles. Therefore, any pre-workout meals or snacks may upset your stomach during a hard workout or a fast run.

#2: Running Too Soon After Eating

One of the most common causes of stomach pain after running is running too soon after eating or eating too much before your workout. This can cause anything from bloating and belching to side stitches and nausea.

#3: Poor Fitness

If you are deconditioned or returning to running after an injury, you may be more prone to side stitches. Weak abdominal muscles, heavy breathing, rapid breathing, and poor running form can contribute to side stitches.

#4: Drinking Carbonated Beverages

Running after drinking carbonated beverages like seltzer, soda, and beer can trigger stomach pain after running because the bubbles contribute to bloating

Colas are double offenders because caffeine has a stimulating effect on the GI tract and bowels and can cause diarrhea when you run.

A plate of fatty foods and carbonates beverages including chips, cookies, candy, a muffin, bread, and a hamburger.

#5: Drinking Too Much Water

Runners know that drinking water and staying well hydrated is important for health and athletic performance, but drinking too much water can cause a stomach ache after running.

Studies have shown that drinking plain water causes people to feel more bloated compared to drinking electrolyte– or carbohydrate-infused beverages. Plain water can also be absorbed more slowly than sports drinks with electrolytes, so you can feel a sloshing sensation and experience an upset stomach after running if you guzzle too much plain H2O.

More importantly, drinking too much plain water, in the absence of taking in electrolytes, while running disrupts the fluid balance in your body. This can lead to a dangerous condition known as hyponatremia

Hyponatremia results when the sodium content in your cells is diluted too much by an excessive intake of water. Cells retain water and swell, causing water retention and bloating, and if severe, even coma and death.

#6: Dehydration

On the other end of the hydration spectrum, dehydration can also lead to stomach problems while running or stomach pain after running.

Dehydration can slow the gastric emptying rate, leaving undigested food to sit around in your stomach if you go running too soon after eating.

Additionally, if you’re dehydrated, your stomach tries to compensate for the lack of fluid in the body by retaining water. Because you sweat when you exercise, dehydration is exacerbated after a run, which can lead to stomach bloating or indigestion after working out. 

A woman drinking a sport's drink.

#7: Fatty Food

Running after eating a fatty meal is a recipe for stomach problems. A fatty meal sits around longer in the stomach and takes longer to be digested, which can lead to stomach cramps when running or an upset stomach after running.

While eating vegetables and legumes is certainly healthy and should be encouraged for all runners, fibrous foods and running don’t mix well.

#8: Too Much Fiber

Fiber acts on the digestive system in multiple ways. For example, it slows the rate of gastric emptying, which is good in some ways because it can make you feel fuller for longer, but it can cause bloating and cramping while you are running.

Fiber also bulks up the volume of food and eventual stool in your digestive tract, stimulating peristalsis and contributing to a feeling of heaviness, distention, or bloating of your abdomen.

Running after eating a meal or snack high in fiber can cause indigestion, bloating, gas, flatulence, diarrhea, and digestive distress while you are running.

#9: Running In the Heat

Stomach problems while running are especially common if it’s hot, humid, or stuffy where you are working out.

When the body temperature rises, blood vessels dilate in an attempt to cool your body down. The heat can also throw off your fluid balance and increase your exertion level and respiration rate, all of which can cause various stomach issues while running, such as cramps, side stitches, bloating, and nausea.

A woman experiencing stomach pain after running.

#10: Poor Breathing Patterns

Holding your breath, gulping too much air, or rapid and shallow breathing can cause side stitches when you run.

#11: Underlying Digestive Disorders

Despite all the wonderful disease-lowering benefits of running, runners are not immune from various digestive disorders like celiac disease, irritable bowel syndrome, Crohn’s disease, colitis, and other inflammatory bowel issues.

The jostling and impact of running can sometimes exacerbate these issues.

#12: GERD

Similarly, GERD, Gastroesophageal reflux disease, and heartburn can flare up and cause stomach pain after running, particularly if you run after eating a meal.

How to Prevent Stomach Problems When You Run 

Given the litany of possible causes of an upset stomach while running or stomach pain after running, it can be difficult to pinpoint the exact issue and fix the problem. However, here are some useful solutions to stomach problems while running:

A tub of ginger chews.

#1: Examine Your Fueling Strategy 

Ensure you’re waiting long enough to go running after eating. You should 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.

Limit fatty foods, fibrous foods, artificial sweeteners, carbonated beverages, and excessive caffeine before you run.

#2: Rethink Hydration

If you are well-hydrated, your urine should be pale yellow. If you are feeling bloated, consider sports drinks with electrolytes.

The general recommendation is to drink 4-6 ounces of fluid every 15 to 20 minutes during your run, depending on the environmental conditions, your sweat rate, the intensity and duration of the run, and your pre-run hydration status. 

For longer runs (60 minutes or more), alternate between water and sports drinks with electrolytes. 

A woman doing a side plank.

#3: Slow Your Pace

Slowing down will reroute more blood to your stomach and digestive tract. It also eases respiration and can prevent stitches.

#4: Fix Your Running Form

Hunching over can compress your diaphragm and lungs and can cause side stitches while running. Make sure you are running tall.

#4: Strengthen Your Core

A strong core can support good running form and prevent side stitches.

#5: Breathe Evenly

Slow, even breathing while running can prevent side stitches and ensure you don’t swallow too much air, which can lead to bloating, belching, and flatulence.

#6: Avoid the Hottest Part Of the Day

During hot, humid weather, try to run in the cooler morning hours or evening hours, or consider taking your workout to a treadmill indoors

#7: Try Ginger Chews

Ginger can ease nausea and indigestion. Try some ginger chews!

A person at a doctor's appointment.

#8: See a Gastroenterologist 

If you have concerns about a gastrointestinal disorder that might be interfering with your running and overall health, speak with your doctor about seeing a specialist.

Let’s get to the bottom of why you have an upset stomach after running, or stomach cramps when running by going through these lists and figuring out the probable culprit and possible solution.

If you are looking to try out a new nutritional routine hoping to improve your tummy troubles, check out our articles on runners’ nutrition:

Running Nutrition Guide: What to Eat For Runners

The Best Popular Diets For Runners

A person holding their stomach in pain.
Amber Sayer

Amber Sayer

Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, and contributes to several fitness, health, and running websites and publications. 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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