Can Exercise Cause Diarrhea?

Yes, exercise can cause diarrhea. 

Exercise has a long list of health benefits, from boosting mood to improving cardiovascular health to strength training for an athlete. 

However, one aspect of physical activity that’s not often discussed but can affect many individuals is diarrhea. Yes, you read it right –studies suggest that 30–50 % of athletes and active people experience digestive distress during or after exercise. 

In this blog post, we’ll explore the reasons behind exercise-induced diarrhea, discuss specific exercises that may trigger it, and provide valuable insights into prevention, treatment, and when to seek professional advice.

Reasons Behind Exercise-Induced Diarrhea

Several factors contribute to the onset of diarrhea during or after exercise. Understanding these can help individuals make informed choices to avoid exercise-induced diarrhea:

Blood Flow Redistribution

Blood is redirected from the digestive system to the muscles when we exercise. This shift can lead to decreased absorption of water and nutrients in the intestines, resulting in loose stools or diarrhea.

Dehydration

Intense physical activity can lead to dehydration, especially in hot conditions. Dehydrated individuals often experience softer stools or diarrhea as the body attempts to conserve water. 

Even just being 1-2% dehydrated can negatively impact your workout and performance, so it’s important to stay hydrated for multiple reasons. 

Increased Gut Permeability

Some studies suggest that strenuous exercise may temporarily increase the permeability of the gut lining. This heightened permeability can allow bacteria or toxins to enter the bloodstream, triggering diarrhea as the body attempts to expel them.

Foods Consumed Before Exercise

Certain foods, especially those high in fiber or fatty foods, can be harder to digest during physical activity. Consuming these foods too close to your workout or right after may contribute to gastrointestinal issues, including diarrhea.

Irritable Bowel Syndrome (IBS)

Individuals with IBS often have a hypersensitive gut, making them more susceptible to changes in bowel habits triggered by various stimuli, including physical activity. The stress placed on the gastrointestinal system during exercise, coupled with factors like altered blood flow and increased gut permeability, can exacerbate IBS symptoms, leading to diarrhea.

Can Specific Exercises Cause Diarrhea More Than Others?

While any exercise has the potential to cause digestive distress, some are more commonly associated with exercise-induced diarrhea:

Running

Long-distance running, in particular, is notorious for triggering diarrhea, earning the term “runner’s diarrhea.” According to studies, the constant jostling and the impact on the lower abdomen can stimulate bowel movements.

High-Intensity Workouts

Intense activities, such as HIIT (High-Intensity Interval Training), CrossFit, or heavy weightlifting, can increase the likelihood of exercise-induced diarrhea due to the stress placed on the body.

Endurance Training

Prolonged periods of exercise, such as cycling, swimming, or marathon running, can exacerbate blood flow redistribution and contribute to dehydration, both potential causes of diarrhea.

Other Gastrointestinal Problems 

In addition to diarrhea, other gastrointestinal problems associated with exercise, often due to the physiological stress placed on the digestive system, can include:

• Bloating: Intense exercise can lead to increased gas production and swallowed air, causing the sensation of bloating. Reduced blood flow to the digestive system during exercise may also slow down digestion, contributing to this discomfort.

• Cramping: Dehydration, electrolyte imbalances, and altered blood flow can lead to muscle cramps in the gastrointestinal tract, causing pain and discomfort during or after exercise.

• Nausea: Strenuous physical activity diverts blood away from the digestive system to the muscles, potentially leading to feelings of nausea. Dehydration and low blood sugar levels are also contributing factors to this sensation.

• Flatulence: Increased movement in the digestive tract during exercise, along with changes in diet and swallowed air, can result in increased flatulence.

• Gastroesophageal Reflux Disease (GERD): Exercises that involve bending or lying down can exacerbate GERD symptoms. Additionally, vigorous activities may increase intra-abdominal pressure, promoting the reflux of stomach contents into the esophagus.

• Constipation: While less common, some individuals may experience constipation after exercise. Dehydration, changes in routine, and reduced blood flow to the intestines can contribute to slowed bowel movements.

Individuals participating in high-impact or prolonged activities may be more susceptible to these issues.

Prevention Tips

While it’s challenging to eliminate the risk of exercise-induced diarrhea completely, several strategies can help minimize the likelihood:

Hydration: Maintain adequate hydration before, during, and after exercise to prevent dehydration, a common trigger for diarrhea. Incorporate electrolyte-rich beverages to aid in maintaining fluid balance.

Timing of Meals: Allow sufficient time for digestion (usually 30 minutes to 2 hours prior) before engaging in strenuous exercise. 

Right kinds of pre-workout foods: Avoid consuming high-fiber or fatty foods close to your workout.

Experiment with Nutrition: Identify which foods your body tolerates well before exercise. Some individuals may need to adjust their pre-workout nutrition to minimize gastrointestinal distress.

Working with a sports dietitian will help you find the right pre-workout and post-workout food that fuels your body properly.

Gradual Intensity Increase: If you’re new to exercise or planning an intense workout, gradually increase the intensity to allow your body to adapt.

Treatment Options 

As mentioned before, diarrhea after exercise is common and should usually clear up within 24-48 hours. If diarrhea occurs during or after exercise, there are several measures individuals can take to help with a speedy recovery:

• Hydration: Rehydrate with water or electrolyte-rich beverages to replace lost fluids.
• Rest: Allow your body time to recover. Avoid strenuous exercise until gastrointestinal symptoms subside.

• Nutrition: Consume easily digestible foods to support recovery without further irritating the digestive system. Avoid high-fiber or greasy foods.
• Over-the-counter medications: Over-the-counter medications, such as anti-diarrheal medications like loperamide or bismuth subsalicylate, can effectively relieve diarrhea by slowing down bowel movements and reducing the frequency of loose stools.

When to Worry 

If diarrhea persists for more than 48 hours, despite these measures, or is accompanied by severe symptoms such as dehydration, dizziness, or persistent abdominal pain, it’s crucial to seek medical advice. 

Persistent symptoms could indicate an underlying issue that requires professional attention.

Conclusion: Can Exercise Cause Diarrhea?

Exercise-induced diarrhea may be an uncomfortable reality for some, but understanding the factors contributing to it and adopting preventive measures can significantly reduce its occurrence. 

Can exercise cause diarrhea? Yes…Should it?…No. 

If you find yourself grappling with persistent gastrointestinal issues during or after exercise, seeking guidance from a dietitian can be instrumental in tailoring nutrition strategies to your specific needs.

Whether you’re a seasoned athlete or you’re just starting your fitness journey, a personalized approach to your dietary needs can make a substantial difference in achieving your health and performance goals.
If you’re looking for a sports dietitian to help you optimize your performance, health, recovery, and sleep by optimizing your fueling and hydration plan, we’re here to help. Check out our customized nutrition counseling packages to learn more.