Exercise-Induced Gastrointestinal Symptoms in Endurance Athletes: Mechanisms, Prevention, and Management – A Narrative Review

Background: Gastrointestinal (GI) symptoms are common among endurance athletes and may impair performance, particularly during prolonged, high-intensity exercise in hot environments or under conditions of dehydration. These disturbances are collectively referred to as Exercise-Induced Gastrointestinal Syndrome (EIGS). Objective: This review summarizes current evidence on the epidemiology, pathophysiological mechanisms, consequences, and prevention strategies for EIGS in endurance athletes. Methods: A narrative review of the literature was conducted, focusing on the prevalence of GI symptoms during endurance exercise, the underlying mechanisms of EIGS—including splanchnic hypoperfusion, epithelial barrier disruption, ischemia-reperfusion injury, mechanical stress, nutritional factors, and neuroendocrine responses—and evidence-based prevention and management strategies. Results: GI symptoms affect approximately 30–50% of endurance athletes, with the highest prevalence reported in marathon, ultra-endurance, and triathlon events. EIGS results from the interaction of reduced splanchnic blood flow, hyperthermia, epithelial injury, and nutritional and mechanical stress, leading to increased intestinal permeability, inflammation, impaired fluid and nutrient absorption, dehydration, and reduced athletic performance. Hypertonic carbohydrate intake, high-FODMAP foods, and nonsteroidal anti-inflammatory drug use may increase symptom risk. Individualized nutrition and hydration strategies, gut training, and low-FODMAP dietary approaches in susceptible athletes may reduce symptom severity. Conclusions: EIGS is a multifactorial condition driven by interacting circulatory, thermal, mechanical, nutritional, and neuroendocrine stressors. Although no single intervention completely prevents GI symptoms, individualized fueling strategies and gut training appear to be the most effective current approaches. Further research is needed to optimize prevention and identify factors underlying individual susceptibility.