Managing Runner's Trots (Exercise-Associated Diarrhea)
The most effective management strategy for runner's trots involves an individualized three-pronged approach: gut training protocols with carbohydrate-electrolyte beverages, dietary modifications (particularly a 24-48 hour low FODMAP diet before running), and strict avoidance of NSAIDs. 1
First-Line Prevention Strategies
Dietary Modifications (24-48 Hours Pre-Exercise)
- Implement a high carbohydrate, low FODMAP diet starting 24-48 hours before running to reduce gastrointestinal symptoms 1
- Avoid high-fiber foods in the day or days before competition, as ultra-endurance athletes consistently report increased lower-abdominal discomfort, flatulence, urge to defecate, and diarrhea with high fiber intake 1
- Eliminate high-fructose foods, particularly drinks containing exclusively fructose (though fructose-glucose combinations may be better tolerated) 1
- Avoid protein, fat, and milk products before and during exercise 1
During Exercise Nutrition
- Consume carbohydrate and/or protein immediately before and frequently throughout exercise within individual tolerance 1
- Identify individual feeding tolerance (approximately 1 g/kg body mass/hour as a starting point) 1
- Ingest carbohydrates with sufficient water or choose lower carbohydrate concentration drinks to prevent high osmolality in the stomach 1
- Avoid dehydration, as it exacerbates gastrointestinal symptoms; start running well-hydrated 1
Gut Training Protocol
Implement repeated fluid tolerance training sessions consisting of 90-minute runs at 65% VO2max every 7-11 days, ingesting carbohydrate-electrolyte beverages (4% w/v) every 10 minutes to match sweat losses (typically >800 mL/hour) 1. This protocol significantly improves stomach comfort through sensory desensitization to increased intragastric pressure, even without changes in gastric emptying rate 1.
Critical Avoidance Strategies
Medications
Strictly avoid NSAIDs (ibuprofen, aspirin) before and during running 1. NSAIDs increase gastrointestinal permeability 3-5 fold, aggravate exercise-induced small intestinal injury, induce gut barrier dysfunction, and can cause mucosal bleeding or perforation 1.
Cooling Strategies
Apply cooling strategies to limit substantial rises in core body temperature (≥39.5°C), as hyperthermia exacerbates gastrointestinal symptoms 1
Strategies to Avoid (Ineffective or Harmful)
The following interventions have no proven benefit and should not be recommended 1:
- Hyperhydration strategies (glycerol, sodium loading)
- Gluten-free diets (unless celiac disease present)
- Low carbohydrate high fat (ketogenic) diets
- Nutritional supplements (glutamine, arginine, antioxidants, probiotics, synbiotics, bovine colostrum, nitrate)
- Pharmaceutical interventions (antiemetics, antacids)
- Compression socks
- Physical maneuvers
Acute Symptom Management
For acute diarrhea during or immediately after running, loperamide can be considered at prescribed dosages (2 mg, up to 16 mg maximum daily dose) 2. However, caution is warranted as loperamide carries risks of QT prolongation, cardiac arrhythmias, and drug interactions with CYP3A4/CYP2C8 inhibitors 2.
When to Escalate Care
Refer to gastroenterology if the runner exhibits:
- Blood in stool
- Fever with abdominal distention 2
- No clinical improvement within 48 hours of conservative management 2
- Recurrent episodes despite implementing first-line strategies 1
Critical Pitfall to Avoid
Do not provide generalized recommendations without individualized assessment 1. The 2025 Sports Dietitians Australia guidelines emphasize that large individual variation exists in gastrointestinal responses to exercise, and each athlete case is unique 1. Underlying predispositions, established diseases/disorders, or health-influencing behaviors may alter gastrointestinal integrity and require tailored interventions 1.
Practice Implementation
Require runners to practice their nutrition strategy multiple times before race day to identify what works and what triggers symptoms 1. This "nutritional training" approach reduces the likelihood of race-day gastrointestinal distress 1.