How to Fuel a Long Run: Carbs Per Hour, Gels, and Fluids
Most runs need nothing but water, and plenty of long runs need only a little. Past about 75 minutes, taking in carbohydrate during the run makes the last third feel like the first, and on race day it is the difference between finishing strong and fading. The numbers below are the consensus ranges for healthy adults; they are not personal nutrition advice.
Who this is for
Runners building toward a half marathon or marathon, or anyone whose long run is heading past an hour and a quarter. If you have diabetes, take medication that lowers blood glucose, or manage any condition that affects nutrition or hydration, work fueling out with your care team instead of a guide.
Do you need to fuel at all?
Carbohydrate need is set by duration and, to a lesser degree, intensity. The joint position statement of the American College of Sports Medicine, the Academy of Nutrition and Dietetics and Dietitians of Canada (Thomas, Erdman and Burke 2016) and the duration-based guidelines in Jeukendrup 2014 agree on the shape:
| Run duration | Carbohydrate during the run | Rebound's plan |
|---|---|---|
| Under 45 minutes | None needed | None |
| 45 to 75 minutes | None needed (a carbohydrate mouth rinse helps at race effort) | None |
| 1 hour 15 to 2 hours 30 | 30 to 60 grams per hour | 35 grams per hour |
| 2 hours 30 to 3 hours | 45 to 60 grams per hour | 50 grams per hour |
| Over 3 hours | Up to 90 grams per hour, only with a glucose plus fructose mix and a trained gut | 60 grams per hour |
Two reasons Rebound sits at the conservative end of each band: a single carbohydrate source absorbs at up to about 60 grams per hour, and more than that only works with a mixed-sugar product and practice. The 90 gram figure is for long events and trained guts, not a first half marathon.
A simple gel schedule
A standard energy gel carries about 20 to 25 grams of carbohydrate; Rebound counts one as 22.
- First gel about 30 minutes in. Absorption lags by 15 to 30 minutes, so the first dose goes in before you feel you need it.
- Then at a steady interval set by the target rate: roughly every 40 minutes at 35 grams per hour, every 25 minutes at 50, every 20 minutes at 60.
- Nothing in the final 25 minutes. It will not absorb before you finish.
- Carry a spare on any run of two and a half hours or longer.
Example: a two-hour long run at 35 grams per hour is a gel at about 30 minutes and another at about 70, then nothing, because a third would fall inside the final 25 minutes. Two gels, a little water with each.
Fluid and sodium
- Drink to thirst, within a sensible range. Typical sweat rates put fluid needs around 0.4 to 0.8 litres per hour; the goal is to avoid losing more than about 2 percent of body weight, and never to gain weight during a run (Sawka et al. 2007).
- Overdrinking is the dangerous mistake. The international consensus on exercise-associated hyponatremia is that drinking to thirst is the safest universal instruction; forcing plain water in beyond thirst dilutes blood sodium, and that is the error that puts runners in hospital (Hew-Butler et al. 2015).
- Sodium matters past two hours or in heat. Around 300 to 600 milligrams per hour from a drink mix or salt tablets is the commonly used range. If you have high blood pressure, a kidney or heart condition, or take diuretics, confirm sodium use with your clinician first.
Practice it
The gut adapts. Stomach comfort, gastric emptying and how much carbohydrate you can absorb all improve with repeated exposure, and gut problems on race day are far more common in runners who never fuelled in training (Jeukendrup 2017). Practice the exact products, amounts and timing you will use on race day on your long runs, several times. Race day is never the day to try something new.
Stop and talk to a clinician if
- Confusion, a severe headache, vomiting, or swelling of the hands and feet during or after a long run. Overhydration can cause these, and it is a medical emergency.
- Bloating, nausea or a sloshing stomach that does not settle when you stop drinking.
- Any fueling question that touches a medical condition or medication.
How Rebound fits in
Rebound Training attaches a fueling plan to long runs and to race day, built from the expected duration of that run: carbohydrate grams per hour, the number of gels, the minutes at which each goes in, and fluid and sodium notes for the runs long enough to need them. Runs under about 75 minutes carry no fueling plan, because they need none. The reminder to practice race fueling in training ships with every plan. All of this is general fitness information for healthy adults and it is written as static text, never generated on the fly.
Rebound is a fitness product, not medical care. This article is general education, not medical or dietetic advice, and nothing here is a diagnosis. If you have diabetes, take blood-glucose-lowering medication, or manage a medical condition affecting nutrition or hydration, work out fueling with your care team.
Sources
- Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine joint position statement: nutrition and athletic performance. Med Sci Sports Exerc. 2016;48(3):543-568. PubMed 26891166
- Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014;44 Suppl 1:S25-S33. PubMed 24791914
- Jeukendrup AE. Training the gut for athletes. Sports Med. 2017;47 Suppl 1:101-110. PubMed 28332114
- Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand: exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377-390. PubMed 17277604
- Hew-Butler T, Rosner MH, Fowkes-Godek S, et al. Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clin J Sport Med. 2015;25(4):303-320. PubMed 26102445
- Kerksick CM, Arent S, Schoenfeld BJ, et al. International Society of Sports Nutrition position stand: nutrient timing. J Int Soc Sports Nutr. 2017;14:33. PubMed 28919842