Long-Course Fueling Plan

From your estimated bike and run times and body weight, get carbs, fluid and sodium targets plus a schedule for the bike and run legs.

Fueling Settings

Race distance (switching fills in suggested times, edit freely)

Bike leg time

hh:mm

Run leg time

hh:mm

Body weight: 68 kg

Hot / humid conditions (raise fluid & sodium)

Carb target (glucose + fructose dual-source, g/h)

Standard 75 g/h: needs glucose + fructose, the sweet spot for most 70.3 athletes; run drops to 65 to protect the gut.

Enter your estimated bike and run leg times to see the fueling plan.

Theory

Long-course triathlon (70.3 / IRONMAN) runs 4+ hours, so glycogen will empty and you must rely on external carbohydrate. Jeukendrup (2014) notes that a single glucose source is limited by the intestinal transporter SGLT1 to about 60 g/h; fructose uses a different transporter, GLUT5, so combining glucose + fructose bypasses the single-source ceiling and pushes carb oxidation above 90 g/h — which is why long-course fuel is often labeled "2:1 glucose:fructose". The run leg is harder to tolerate due to impact and posture, so this tool trims run carbs slightly.

Hyponatremia risk: the longer and hotter the race, the more that plain water alone dilutes blood sodium and can trigger hyponatremia (dizziness, nausea, even seizures). Take sodium too (electrolyte capsules / sports drink), tuned to your sweat rate and saltiness — don't just chase fluid.

Sources: Jeukendrup 2014, Sports Med

Pair with other tools

Pace Splitter

Finish Predictor

Transition Checklist