Race fuelling
Enter your goal time and the weather, and we lay out the hourly carbohydrate, fluid and sodium ranges plus the race total.
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For example 3:30 (3 hours 30 minutes) or 45:00 (45 minutes).
Carbohydrate · per hour
60-90 g
225-338 g of carbohydrate in total: roughly 9-14 gels (25 g each) or 6-8 energy bars (40 g each). Mixing the two is easier on the stomach.
| per hour | Total for the race | |
|---|---|---|
| Carbohydrate | 60-90 g | 225-338 g |
| Fluid | 400-600 ml | 1500-2250 ml |
| Sodium | 300-700 mg | 1125-2625 mg |
These are general ranges, not medical advice. Test any new fuelling plan in training, never for the first time in a race.
The ranges follow common sports nutrition guidance: under an hour extra carbohydrate is usually not needed, between one and two and a half hours aim for 30-60 g per hour, and beyond that 60-90 g per hour. Fluid and sodium needs rise in heat; measuring your own sweat rate makes the numbers sharper.
These are general ranges and assume normal conditions. Trail, heat, elevation gain, wind and technical ground all make the real time longer.
Frequently asked questions
(10)
How do I take 90 g of carbohydrate an hour?
Products mixing glucose and fructose (2:1) improve gut tolerance. That intake has to be trained: build up to it gradually on long runs.
Gels or sports drink?
Both are carbohydrate; the difference is gut tolerance and how much fluid you need. Drinks are easier in heat, gels more practical in the cold.
What should I eat before a race?
Target 1-4 grams of carbohydrate per kilogram of body weight 3-4 hours before the start, which is 70-280 grams for a 70 kg runner. Keep fat and fibre low because they slow gastric emptying, and never try a new breakfast on race morning.
How often should I take a gel?
A gel holds 22-25 grams of carbohydrate on average. For 60 grams an hour take one every 20-25 minutes; for 90 grams an hour every 15-20 minutes. Your gut only tolerates that rate if you train it in long runs.
How do I avoid stomach problems?
Three rules work: rehearse race products in long runs, choose a glucose plus fructose mix once you go above 60 grams an hour because they absorb through separate routes, and take gels with water. Concentrated sugar with little water is the most common cause of nausea.
Do I need to fuel during a 10K?
Below 60-75 minutes extra carbohydrate does not measurably change performance; your muscle glycogen is enough. In the heat, water and rinsing your mouth with a carbohydrate drink are all you need.
When should I take the first gel?
If the race will take more than 90 minutes, take the first gel at 30-45 minutes: starting before you are empty is easier than catching up later. Continue every 25-35 minutes. Under an hour, extra carbohydrate is unnecessary for most runners.
How do I avoid stomach trouble in a race?
Your gut trains too: rehearse the exact product and amount on long runs for weeks. If you target 90 grams per hour, use a glucose plus fructose product, because single-source carbohydrate absorption caps around 60 grams. Always take gels with water; a gel washed down with sports drink doubles the sugar concentration.
How does carbohydrate loading work?
For a marathon or longer, aim for 8-10 grams per kilogram of body weight in the last two to three days: 560-700 grams a day for a 70 kg runner. Cut fat and fibre and reduce training volume. Gaining 1-2 kg of water is the expected side effect, and that weight comes back as fuel.
When should I use a caffeinated gel?
The effect peaks at 30-45 minutes, so place caffeine in the last third of the race: kilometre 25-30 of a marathon, or the night section of an ultra. Keep the total to 3-6 milligrams per kilogram and rehearse it in training, because caffeine gives some athletes stomach trouble and a higher heart rate.