“Runner’s diarrhea” is a common and often frustrating experience for many athletes, affecting individuals across all running levels. This phenomenon, sometimes called “runner’s trot,” can significantly impact performance and overall comfort during and after a run.
Understanding Runner’s Diarrhea
Runner’s diarrhea refers to frequent, loose bowel movements during or shortly after physical activity. Common symptoms include abdominal cramps, an urgent need to use the bathroom, loose stools, gas, acid reflux, and nausea. While disruptive, this exercise-induced digestive issue is typically temporary and often benign for most individuals. It is particularly prevalent among long-distance runners, with some studies indicating that up to 62% have had to stop during a run for a bowel movement.
Physiological Factors at Play
Several physiological mechanisms contribute to runner’s diarrhea. During intense exercise, the body redirects blood flow away from the digestive system towards working muscles, the heart, and lungs. This reduced blood supply, known as ischemia, can impair gut function and make digestive tissues more sensitive.
The physical motion of running also plays a role. Repetitive jostling of internal organs causes mechanical stress on the gastrointestinal tract. This agitation can contribute to discomfort, increased gut motility, and an urgent need for a bowel movement.
Exercise triggers hormonal changes, releasing stress hormones like cortisol and adrenaline. These hormones influence gut motility and accelerate food transit time. This increased speed can lead to less water absorption and looser stools.
Dehydration and electrolyte imbalances further exacerbate digestive issues. Insufficient fluid intake can irritate the gut lining and hinder digestion. Dehydration also reduces overall blood volume, which can intensify the reduced blood flow to the colon. Conversely, excessive fluid intake can also lead to stomach upset.
Dietary and Training Adjustments
Managing runner’s diarrhea often involves strategic dietary and training adjustments. Before a run, consider the timing and composition of meals. It is advisable to avoid eating anything for at least two hours prior to exercise. For longer runs, a window of two to four hours for a more substantial meal is suggested.
Dietary Adjustments
Certain foods are known triggers and should be limited or avoided before a run.
High-fiber foods (e.g., beans, bran, certain fruits, vegetables)
High-fat foods
Spicy foods
Foods containing artificial sweeteners or sugar alcohols
Caffeine can also stimulate bowel movements and may need to be restricted. Experimenting with different foods during training helps identify individual triggers. Opt for easily digestible, low-fiber carbohydrates like white rice, toast, or plain pasta before a run to provide energy without stressing the digestive system.
Hydration is important. Maintain adequate hydration before, during, and after runs, but avoid drinking large quantities of water at once. Small, frequent sips of water, around 5 to 10 ounces every 15 to 20 minutes during a run, are often recommended. Sports drinks, energy gels, and energy bars should be tested during training, as they can sometimes contribute to diarrhea.
Training Adjustments
Gradually increase mileage and intensity to allow the body to adapt. Sudden changes in intensity can overwhelm the digestive system. Incorporating warm-up and cool-down periods can also help. Establish a consistent bathroom routine before a run to minimize mid-run urgency. Wearing comfortable, loose-fitting clothing around the waist can prevent additional pressure on the abdomen.
When to Seek Medical Attention
While runner’s diarrhea is often a benign issue, certain symptoms warrant medical consultation. If diarrhea persists for more than 24 to 48 hours despite dietary and training adjustments, consult a doctor.
Seek medical attention for signs of dehydration, including:
Excessive thirst
Dry mouth
Reduced urination
Severe weakness
Dizziness
Dark-colored urine
Other reasons to seek professional medical advice include blood in the stool, severe abdominal pain, or unexplained weight loss. If diarrhea occurs frequently outside of running or is associated with a fever, a healthcare provider can help determine if there is an underlying chronic gastrointestinal condition, such as irritable bowel syndrome (IBS).