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Runner's Trot: Why Your Gut Screams During Marathons
26 Apr
Summary
- Running decreases blood flow to the gut, causing urgent bowel movements.
- Track heart rate during training to predict and manage 'runner's trot'.
- Avoid coffee and sugary drinks; opt for electrolytes for hydration.

As the London Marathon approaches on April 26, 2026, a gastroenterologist offers insights into 'runner's trot,' a common issue for marathon participants. Dr. Trisha Pasricha explains that during intense running, blood flow to the intestines can decrease significantly, leading to an urgent need for the bathroom, often felt around mile 18.
This reduction in blood flow causes the gut to signal distress, making runners feel unwell and necessitating a trip to the toilet. Dr. Pasricha suggests using fitness trackers to monitor heart rate during training. Identifying the heart rate threshold at which symptoms appear can help runners adjust their training pace to avoid this.
She further advises runners to prioritize hydration with electrolyte-rich beverages rather than sugary drinks. Additionally, she recommends avoiding coffee on race day, as its stimulant effect can further activate the colon, which should ideally be kept calm during a marathon.