Long Session Fuelling Planner
Plan the carbohydrate, fluid and sodium intake for a long run, ride or race by duration, intensity, body weight and conditions — output as an hour-by-hour schedule.
How this is worked out
Carbohydrate. Targets follow the current sports-nutrition consensus: roughly 30 g/h for easy long efforts, 60 g/h at sustained race intensity, and up to 90 g/h only where a mixed glucose–fructose source is used. Glucose saturates its intestinal transporter around 60 g/h; fructose uses a separate one, which is what makes the higher rates absorbable. Running gets a lower figure than cycling because the gut tolerates less while you are being jostled.
Fluid and sodium. Sweat rate is estimated from intensity, conditions and body mass, scaled against a 70 kg reference. This is a planning figure: weighing yourself before and after a session in similar conditions, and counting 1 kg lost as 1 litre, will beat any formula for you specifically.
Sessions under an hour need no fuelling — stored glycogen covers them, and water to thirst is enough.
Information only — not medical advice. These are estimates from population-level formulas, not a substitute for professional assessment. See our full disclaimer.