Exercise places stress on your system, although it’s a good type of stress, the kind that forces your cardiovascular system and muscles to adapt and become stronger and more efficient. However, exercise can create temporary problems for your digestive system. So common is digestive upset with exercise that it has a name, exercise-induced gastrointestinal syndrome.
Digestive symptoms are most common in people who run or cycle, but even weightlifters can have digestive issues such as acid reflux or nausea when they lift heavy weights. Intensity matters too. Up to 50% of people who do intense endurance exercise experience problems related to their intestinal tract during a workout, and it’s more common among women and younger athletes.
For most people, these symptoms aren’t indicative of a serious health problem, but it’s a good idea to have digestive symptoms checked out by a doctor if they’re persistent. If you already have digestive issues, like acid reflux or irritable bowel syndrome, exercise can temporarily make the symptoms worse. It’s a good idea to talk to your physician and get their recommendations for managing these conditions when you work out. However, in healthy people, the symptoms are related to your workout and usually don’t indicate serious pathology.
Common Digestive Problems That Can Happen During Exercise
When you exercise, blood is diverted away from your intestines to the hard-working muscles that are working harder. This shift in blood flow slows down stomach motility and digestion and causes foods and liquids to stay in your gut longer. When you exercise, this can trigger nausea, fullness, and bloating. In some people, the discomfort is so pronounced they have a difficult time completing their workout.
When you exercise on a full stomach, the jostling motion can disrupt the proper functioning of your digestive tract. Plus, contracting your abdominal muscles, as most people do during exercise, places added pressure on the gastrointestinal tract. It can all add up to unpleasant digestive symptoms that make working out harder.
Some weightlifters, runners, and cyclists may experience a burning discomfort in their chest and an acid taste in their mouth from acid moving back into their esophagus from their stomach. When you lift weights, it increases the pressure within your abdominal cavity. The pressure pushes back on your stomach and esophagus and causes acid to flow back into the esophagus and throat. People with a condition called GERD, another name for chronic acid reflux, have this symptom even when they’re not exercising, which usually requires treatment with medications, but others have it only when they work out. Running can worsen acid reflux too due to the repeated jarring motion from the impact of their feet hitting the ground.
Some runners and weight lifters also swallow air when they lift, a phenomenon called aerophagia, and swallowed air can lead to bloating, gas, flatulence, and abdominal distension. Many air swallowers aren’t even aware they’re gulping air when the work out. It’s an unconscious habit that increases with workout intensity and may be worsened by stress. Abdominal bloating due to swallowed air is also common among swimmers.
Then there’s the infamous “runner’s trots’, episodes of diarrhea brought on by exercise. This is a malady that affects people who run longer distances. No one knows exactly why long-distance running triggers diarrhea. One theory is that running stimulates the muscles of the colon to contract irregularly. Whatever the cause, it can be a source of distress when there’s no bathroom available and you’re miles from home. The symptoms can be unpredictable too. They may come on suddenly during exercise when you least expect it.
If you have any of these digestive symptoms when you work out, you probably want to know how to control them. Fortunately, there are some simple steps you can take to make exercise less unfriendly to your digestive tract.
How to Prevent Digestive Symptoms During Exercise
- Wait 2 hours after eating before working out. Studies show that acid reflux symptoms and digestive upset are more common when people exercise right after a meal.
- Limit fatty foods before a workout since they delay stomach emptying. If you’re prone to diarrhea, avoid eating high-fiber foods 12 hours before an intense workout. Fiber, too, can slow gastric emptying.
- Don’t chew gum or drink carbonated drinks before exercising. This increases air swallowing and that can lead to abdominal bloating and distension. Plus, abdominal distension from swallowed air can trigger acid reflux.
- Avoid caffeine and dairy products before working out. Caffeine increases acid production and irritates the digestive tract. Plus, it can affect the nerves that control digestive function. If you drink coffee before a workout to improve athletic performance, drink low-acid coffee, and use a dairy alternative if you’re lactose intolerant. Lactose in dairy can cause diarrhea and build-up of gas if you lack enough of the lactase enzyme to break it down.
- Avoid fruits and fruit juices containing fructose before exercising. Some people don’t absorb fructose well and experience gas when they ingest it.
- Don’t take non-steroidal anti-inflammatory medications (NSAID). They can cause stomach irritation and reflux symptoms. Some studies show that taking NSAID, when combined with intense or long-duration exercise, can damage the gut lining. So, limit the use of these medications and drink lots of fluid if you have to use one.
- Stay well-hydrated. This helps to increase blood flow to your digestive tract to keep things moving along as they should.
- See your doctor if you have persistent digestive symptoms when you exercise. You may have lactose intolerance, irritable bowel syndrome, or another condition that needs medical treatment.
The Bottom Line
Now you know why exercise can cause digestive discomfort and some ways to reduce the risk. Watch what and when you eat before a workout and listen to your body. If you experience symptoms, slow or modify your workout. Over time, making small modifications to your diet, when you workout, and the intensity of your workouts can make a difference in your symptoms.
References:
- com. “Nutrition and Exercise Associated Gastrointestinal Problems”
- Running Times. “Fueling the Runner: A Runner’s Nightmare”
- com. “High-Intensity Exercise May Be Bad for the Bowels”
- Sports Med. 2017; 47(Suppl 1): 101–110.
- Published online 2017 Mar 22. doi: 10.1007/s40279-017-0690-6
- org. “Physical Activity and Digestive Health”
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5 of the Most Common Digestive Issues Related to Exercise
5 Foods to Avoid Before a Workout
5 Inconvenient Things That Can Happen During a Workout & What to Do About Them