In 30 seconds
- Half marathon (1-2 hours): up to 30 g of carbohydrate per hour. Marathon (2-5 hours): up to 60 g, and up to 90 g if you go beyond 2.5 hours, mixing glucose and fructose.
- Drink to thirst, without replacing more than 80% of what you sweat. As a guide, 0.4-0.8 litres per hour.
- From one hour onwards, a drink with 400-1,100 mg of sodium per litre.
- Drinking too much is dangerous: hyponatraemia occurs mainly in people who drink more than they sweat.
Race day is not the time to improvise: what you eat and drink on the course is also something you try out in training. These are the reference numbers and how to turn them into your plan.
Your plan, by distance
| Half marathon | Marathon | |
|---|---|---|
| Typical duration | 1-2 hours | 2-5 hours |
| Carbohydrate per hour | Up to 30 g | Up to 60 g; up to 90 g if you go beyond 2.5 hours |
| Type of carbohydrate | Glucose, sucrose or maltodextrin | A mix of glucose and fructose above 60 g/h |
| Fluid | To thirst | To thirst, without exceeding 80% of what you sweat |
| Sodium | If you go beyond one hour, 400-1,100 mg per litre | 400-1,100 mg per litre |
Sources: Jeukendrup, 2014 (carbohydrate); Mosler et al., 2020 (fluid and sodium).
Carbohydrate per hour
Maximum carbohydrate per hour, by race
Carbohydrates: the fuel
In efforts lasting more than an hour, taking carbohydrates during the race helps you hold your pace. How much depends on how long you will be out there 1:
- Half marathon: up to 30 g per hour. See how it applies to the Barcelona Half Marathon.
- Marathon: up to 60 g per hour, and up to 90 g if you go beyond 2.5 hours.
- Above 60 g per hour, mix glucose and fructose. In a study with cyclists, the final time trial was 8% faster with that mix than with glucose alone 4.
Your gut can be trained too: on your long runs, test exactly what you are going to take on race day.
Fluid
How to drink during the race
Fluid: drink to thirst
- Drink to thirst, without replacing more than 80% of what you sweat 2.
- As a guide, 0.4-0.8 litres per hour is usually well tolerated during hard efforts 2.
- To understand your own case, weigh yourself before and after a long run. Our hydration calculator works it out for you. For race day, use the race hydration planner.
Sodium: from one hour onwards
From one hour onwards, your drink should contain 400-1,100 mg of sodium per litre 2. This matters more if you sweat a lot or if the race lasts more than 2 hours 2.
Be careful not to drink too much
Hyponatraemia, a drop in blood sodium, can be serious. During exercise it appears mainly in people who drink more than they sweat, which is why the international consensus recommends letting thirst guide you 3. Do not feel obliged to drink at every drinks station.
Sodium per litre
Your drink's sodium versus the recommended range
With Nitrus Isotonic
Each 25 g scoop of Nitrus Isotonic provides 15 g of carbohydrate and about 195 mg of sodium. Depending on how much water you use:
| Preparation | Sodium per serving | Sodium per litre | Carbohydrates per serving | Carbohydrates per litre |
|---|---|---|---|---|
| 25 g in 400 ml | 195 mg | 488 mg | 15.1 g | 37.8 g |
| 25 g in 500 ml | 195 mg | 390 mg | 15.1 g | 30.3 g |
Each 25 g serving contains 0.488 g of salt (about 195 mg of sodium), 148 mg of potassium and 15.13 g of carbohydrates.
In 400 ml it falls within the recommended sodium range. In a marathon, to reach 60 g of carbohydrate per hour you will need to add gels or another source of carbohydrate: one bottle of Nitrus per hour provides 15 g. If you are running the Barcelona Marathon, your plan is ready, aid station by aid station.
Frequently asked questions
How much water should you drink during a marathon?
Drink to thirst, without replacing more than 80% of what you sweat. As a guide, 0.4-0.8 litres per hour is usually well tolerated during hard efforts. Weigh yourself before and after a long session to understand your own case.
How many gels should you take in a marathon?
It depends on the carbohydrate in each gel and on your time. The reference is up to 60 g per hour, and up to 90 g if you go beyond 2.5 hours, mixing glucose and fructose. Always test it on your long training runs.
Do you need to drink during a half marathon?
If it lasts more than an hour, yes, it is worth drinking to thirst. Carbohydrates help from one hour onwards: up to 30 g per hour.
What is hyponatraemia?
A drop in blood sodium that can be serious. During exercise, it occurs mainly in people who drink more fluid than they lose through sweat, which is why drinking to thirst is recommended.
Sources
- Jeukendrup AE. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014;44(Suppl 1):S25-S33. View publication
- Mosler S, Braun H, Carlsohn A, et al. Position of the working group sports nutrition of the German Nutrition Society (DGE): fluid replacement in sports. Dtsch Z Sportmed. 2020;71(7-9):178-184. View publication
- Hew-Butler T, Rosner MH, Fowkes-Godek S, et al. Statement of the 3rd International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Br J Sports Med. 2015;49(22):1432-1446. View publication
- Currell K, Jeukendrup AE. Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc. 2008;40(2):275-281. View publication
Information based on published studies. It does not replace the advice of a doctor or registered dietitian. The results describe what was measured in each study, not the properties of any specific product. A varied and balanced diet and a healthy lifestyle are important.
