What causes runner's stomach?

Runner's stomach, commonly experienced during running, is primarily caused by the physical jostling of internal organs and the body's reallocation of blood away from the digestive system to the muscles. When running, the repetitive impact causes your internal systems to be repeatedly shaken, which can disrupt your digestive tract. Additionally, the body prioritizes blood flow to the muscles over digestion, reducing blood supply to the digestive tract, which slows down digestion and can lead to discomfort and the need for urgent bowel movements during a run 1.

Another contributing factor is the intake of non-steroidal anti-inflammatory drugs (NSAIDs), which can irritate the gut lining and exacerbate gastrointestinal issues. Also, stress and hormonal fluctuations, including those related to menstrual cycles, can trigger runner’s stomach. Consuming easily digestible snacks before running, like bananas or plain toast, and monitoring your diet can help minimize symptoms. It's crucial to experiment with food and hydration to identify what best suits your body during running 2.