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Running and Digestion

A volunteer hands water for runners during a races.

This post written for US News Health, Eat+Run

Running to the bathroom is not exactly high on the list of things to do to improve your 5K time. Yet at least 60 percent of runners experience intestinal distress resulting from intense and prolonged exercise. Many of those runners have ongoing digestion problems that never seem to work themselves out. These types of intestinal issues cause runners to rely on medications and strict dietary and social routines to manage their distress.

How does running impact digestion?

• Shifting and agitation in the digestive tract and fast fluid shifting in the colon can cause cramping and discomfort.

• Blood diversion from the digestive tract to the muscles causes the digestion system to slow down.

• Depending on the intensity, fast dehydration slows the blood flow back to the intestinal tract.

• A history of gastrointestinal distress brings about stress and anxiety before goal events, which further irritates an already sensitive intestinal system.

What are some risk factors?

Dehydration. Losing fluids from sweat causes dehydration. Most runners do not like the feel or hear the sound of water sloshing in their stomach and may be hesitant to replace lost fluids.

High-fat and high-protein meals. These foods take longer to break down in the digestive tract. The muscles will demand the blood flow from the stomach so those foods remain "stuck" waiting for more help to digest.

Gas-producing foods. No further explanation needed. Lay off the broccoli, cabbage and cauliflower until the celebratory dinner.

Caffeine. We all know it already has a laxative effect on many people. Add intense running, and it’s a recipe for diarrhea disaster.

NSAIDs. Commonly used non-steroidal anti-inflammatory drugs, such as aspirin and ibuprofen, have been associated with gastrointestinal distress, especially when used in the high amounts that are common for some athletes.

What can a runner do to avoid such distress?

1. Eat light three hours before a long run or race.

2. No eating 30 minutes before a run. Sip water or diluted sports drink instead.

3. Lay off the NSAIDs. Don’t do the trick of taking a large dose to "get through" the pain of a current injury.

4. No alcohol, dairy or spicy or gassy foods the night before. Also avoid high-fat and high-protein the night before a big race. Stick to light, easy-to-digest foods.

5. Know your caffeine tolerance. Some drink coffee in plenty of time to "lighten the load" before the race. They have it down to an exact timing.

6. Don’t wait until 30 minutes before the gun to start hydrating. Avoiding dehydration begins 24 to 48 hours prior to a heavy endurance event.

7. Know your sports drinks. Avoid the high-sugar, high-carbohydrate drinks.

In the tips above, there is an emphasis on "know" your tolerance. There’s a golden rule among runners: Never try anything new before or during a race. This is especially true with runners with a history of intestinal distress. During the weeks of training is when you experiment with various fueling and hydration techniques. Experiment with foods and timing. Learn what works for your body long before race day.

Just like training your muscles, you have to train your digestion system. As you gain better fitness, your gastrointestinal system becomes more efficient at keeping blood evenly distributed. Your body becomes better adapted to changing hydration needs. Just like most anything, the beginning is hard. Beginning runners usually experience some type of distress in their first few months of running. Stick to a consistent training plan, and work on finding the right balance between timing and types of fueling