Your race-day nutrition plan — carbs, water, sodium and the feeding cadence — calculated from your race type and goal time. From 10K to ultra.
On a long race, your glycogen stores (your fuel) drain: beyond ~1 h you have to top them up continuously.
Expected benefit: a number-backed plan — carbs, water, sodium and feeding cadence — to finish without bonking or gut trouble.
42 g of carbs / h
to dissolve in 0.6 L of water (~7 % — safe digestive zone).
+ 48 g/h as gels or solids, with plain water (to stay ≤ 8 %).
Feeding timeline
From minute 45, every 30 min: 45 g of carbs + 300 ml of water.
Sip in small, regular amounts rather than all at once; start fuelling early, before you fade.
Over 4 h of racing
Plenty of runners under-fuel on race day: a 4-hour marathon nearly empties glycogen, and 'I'll eat when I get hungry' comes too late. Overloading the bottle, on the other hand, triggers gut trouble. The right dose depends mostly on how long your race lasts — your goal time — not on the brand of gel.
The literature (Jeukendrup) sets carb intake by duration: ~30 g/h up to 2 h, 60 g/h up to 2 h 30, then 90 g/h beyond — up to 120 g/h with a multi-transportable mix (2:1 maltodextrin/fructose) and a trained gut. Water and sodium track the heat and your sweat rate; the bottle concentration stays under 8% so it does not slow gastric emptying.
Three rules: (1) start fuelling early — by minute 45 — do not wait for hunger; (2) train your gut at race pace with your race products, never for the first time on race day; (3) spread intake into small, regular doses (about every 30 min) rather than big hits. The plan gives you the target; your long runs validate it.