Why Running Makes You Poop: A GI Doctor Explains and Offers Tips to Prevent It

If you've ever felt an unexpected urge to find a bathroom mid-run, you're not alone.

This phenomenon, often called "runner's trots" is a common issue among runners. Research shows that up to 84% of runners experience gastrointestinal (GI) symptoms during their runs.

While inconvenient, understanding why it happens can help you take steps to prevent it.

What Causes Runner's Trots?

According to Dr. Linda Nguyen, a gastroenterologist at Stanford Health Care, runner's trots occur because intense exercise activates your sympathetic nervous system (SNS).

This part of your autonomic nervous system controls automatic bodily functions like digestion, sweating, and heart rate.

When you're under stress, such as during a strenuous run, your SNS increases motility, the contractions of muscles in your GI tract, which can lead to diarrhea.

The intensity of your run can influence the severity of symptoms.

Long, intense runs, like marathons, are particularly problematic because blood flow is redirected from your gut to your muscles.

"You need blood flow in the gut to properly digest food," Dr. Nguyen explains. When that process is interrupted, GI distress often follows.

How to Prevent Runner's Trots

While there’s no guaranteed way to avoid GI issues on a run, there are several strategies you can try:

1. Mind Your Pre-Run Meal Timing

Eating too close to your run can increase the likelihood of needing to use the bathroom.

If possible, avoid eating for a few hours before your workout. For runs over an hour, you may need a small snack to maintain energy.

2. Choose the Right Foods

Certain foods are more likely to trigger GI distress. Dr. Nguyen advises avoiding these before a run:

• Dairy products;
• Fruits and juices;
• Onions and garlic;
• Sugary foods or artificial sweeteners;
• High-FODMAP foods (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols).

Instead, opt for:

• Light proteins, like nut butter
• Complex carbohydrates, such as whole grain bread or quinoa

It may take some trial and error to find the best pre-run snacks for your body.

Some runners tolerate small amounts of fruit or a granola bar well, while others need to avoid these entirely.

3. Manage Stress Levels

Stress can exacerbate GI issues, especially before a big race.

Techniques like meditation, deep breathing exercises, or even a warm cup of peppermint tea can help calm your nerves and your stomach.

4. Listen to Your Body

If you feel the urge to go during a run, there’s not much you can do but find the nearest restroom.

However, if this happens frequently, consider adjusting your diet, stress management techniques, or pre-run meal timing.

Conclusion

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While runner's trots can be an unwelcome aspect of running, understanding why it happens and making small adjustments to your routine can significantly reduce the chances of it occurring.

By experimenting with your pre-run snacks, managing stress, and timing meals effectively, you can keep GI distress to a minimum.

So the next time you lace up your running shoes, you can focus on your pace and goals without worrying about unscheduled bathroom breaks. Happy running!