Carbs, Fluid & Sodium: Building Your Ultrarunning Fueling Plan

Elite endurance performance relies on individualized fueling strategies that evolve through data-driven testing and real-time adjustments. Sports scientist Emily Arrell emphasizes that athletes should prioritize measuring sweat sodium concentration and sweat rates to create precise hydration plans rather than blindly mimicking professional intake. Developing gut tolerance for carbohydrates is a gradual, season-long process, requiring consistent training to reach optimal intake levels without triggering gastrointestinal distress. Effective race-day execution involves decoupling fuel and hydration sources to allow for flexible adjustments in response to environmental shifts like heat or humidity. Ultimately, fueling is a trainable skill; athletes who log their intake and subjective responses during training sessions build the necessary foundation to execute a reliable, high-performance strategy on race day.