Intra-Workout Carbohydrates: Do You Really Need Carbs During Training?

It wasn’t until the 1980s that we first learned that intra-workout carbs increased exercise capacity, and it changed the field of sports nutrition. 

When you are exercising, you probably know what to eat before a workout and what to eat after a workout, but do you know what to eat during a workout? 

Today’s article will focus on endurance nutrition. We’ll explore why, if, and when it makes sense to fuel with carbohydrates during a workout, and if so, how much to consume. 

Let’s look at: 

• What are intra-workout carbohydrates?

• Muscle glycogen and performance

• Who benefits from carbs during training? What about carbs for muscle gain?

• What is an effective amount of carbohydrates for athletes?

• Workout nutrition that combines carbs and electrolytes

What are Intra-Workout Carbohydrates?

Intra-workout carbohydrates are carbohydrates ingested during a workout, not for pre-fueling or post-workout glycogen replenishment, but to support performance during activity. 

Glucose is the typical carbohydrate source that athletes use for intra-workout carbs. It can be digested and absorbed into the bloodstream quickly, so it’s available to muscles to burn for energy. Intra-workout carbs may include:

• Goos and gels

• Sports drinks

• Bars (low-fat, low-protein, low-fiber) (1)

Whether you choose a liquid, solid, or semi-solid option, the goal is for the carbs (glucose) to enter the bloodstream rather than accumulate in the intestines and cause gastrointestinal disruption. (1)

Some athletes prefer a food-first approach using whole foods to optimize glycogen stores, combined with specific whole food sources during exercise, including bananas, raisins, or honey, rather than a glucose product. (2) 

How Muscle Glycogen Affects Performance

Glycogen is the human equivalent of starch from a plant. It’s a branched structure of glucose molecules that allows humans to store carbohydrates for later. The hormones, insulin and glucagon, regulate glycogen storage and use. (3, 4)

After a meal, the body converts some glucose into glycogen for storage primarily in the liver and muscles. Glycogen storage is finite, and once it’s full, excess carbohydrates are stored as fat. (3) 

Between meals, overnight, and during exercise, glycogen is broken down to maintain a steady glucose supply in the blood. Glycogen breakdown in the muscle can directly provide glucose to muscle cells to use for energy. (3)

The liver can store around 80 to 120 grams of glycogen, and muscles can store 350 to 700 grams. The amount of glycogen stored depends on sex, weight, diet, training status, and muscle fiber composition. (5, 6)

Research from the 1960s led us to understand the importance of glycogen during exercise. During exercise, the body taps into glycogen stores to maintain a consistent fuel supply and energy. (1, 5)

Who Actually Benefits from Carbs During Training?

Endurance athletes primarily benefit from intra-workout carbohydrates. As glycogen stores become depleted with prolonged cardiovascular activity, intra-workout carbs help provide glucose to the muscles and maintain high rates of glucose oxidation (burning glucose for energy). (1)

Research suggests that intra-exercise carbohydrates increase exercise capacity and improve performance. (1)

However, not everyone may need carbohydrates during a workout. The benefits of intra-workout carbs depend on the duration and intensity of exercise, as well as body size and training status. Additionally, specific sports may have rules and regulations about what’s allowed during competition. (1) 

Typically, intra-workout carbohydrates become more important around the 2-hour mark, when they can help prevent hypoglycemia (low blood sugar). (1)

What about carb timing for resistance training? The relationship between carbs and muscle growth doesn’t rely on intra-workout carbs. 

In a meta-analysis of 49 studies, the authors concluded that intra-workout carbohydrate intake is unlikely to improve strength training performance in workouts comprising up to 10 sets per muscle group. (7)

Another study examined intra-workout carbs during CrossFit sessions and found that they didn’t improve performance, exertion, recovery, or other markers. (8)

Nutrition for muscle growth differs from that for improving endurance performance. But for endurance activities, how many carbs do you need? 

How Much Carbohydrate is Effective?

American College of Sports Medicine recommends 30-60 grams of carbohydrate per hour during endurance training. This range is based on the oxidation of up to 1 gram of carbohydrate per minute, which is considered the highest rate and is limited by intestinal absorption. Other research has determined that 20-22 grams per hour is enough to see a performance benefit. (1) 

Here are some more specific guidelines (1):

Even with these guidelines, your approach will require personalization. Adjust the recommendations downward for lower-intensity activity. Practice your intra-workout carb strategy during training to figure out what works best to optimize performance and minimize GI side effects before competition. 

Practical Intra-Workout Carbs + Electrolytes Setup 

One important note regarding intra-workout carbohydrates is that carb intake needs to be balanced with fluid intake. Concentrated carbohydrates (juice, drinks, gels) can reduce fluid absorption. (1) 

For high-intensity endurance activities lasting over 1 hour, you need supplemental carbohydrates, fluids, and electrolytes. 

You likely already know the importance of electrolytes during a workout to maintain hydration and fluid balance. When it comes to sports drinks vs water, most sports drinks offer carbohydrates and electrolytes. 

Outwork Nutrition Electrolyte Drink Mix combines electrolytes (sodium, potassium, and magnesium) with dextrose, a glucose source, providing 8 grams of carbohydrate per serving. The ratio of carbs to electrolytes in this formula supports optimal hydration before, during, and after exercise. And you can easily pair it with additional carbohydrates when your workout calls for it. 

Final Word

Intra-workout carbs aren’t a big topic in strength training nutrition, but they’re worth considering for high-intensity endurance activity. Many people engage in both types of workouts.  

For high-intensity endurance workouts lasting over an hour, consider experimenting with intra-workout carbs to find the dose and delivery method that work best for your body and goals. If you’re stuck on what to drink during a workout, start with Outwork Nutrition Electrolyte Drink Mix and adjust from there. 

Carbohydrates are an important macronutrient during endurance work, and you’ll want to have some handy as glycogen runs out. 

Intra-Workout Carbs FAQs

Do you really need carbs during a workout? 

Not always. For high-intensity endurance training sessions over 1 hour, consider experimenting with intra-workout carbs to improve performance. You likely don’t need carbs for sessions under 1 hour, low-intensity activity, or for strength training. 

Who benefits most from intra-workout carbohydrates?

Athletes doing long-duration training, multiple sessions per day, or very high-volume workouts will benefit most. 

How many carbs should you take during a workout?

Depending on the duration and intensity, consider 30-90 grams of carbohydrates per hour, or to tolerance. See the chart above. 

Are intra-workout carbs better than pre-workout nutrition?

No. Pre-workout nutrition is typically more important and applies to a broader range of athletes and activities. Intra-workout carbs become a limiting factor when glycogen levels become depleted. You can utilize both pre-workout nutrition and intra-workout carbs as needed. 

What should you drink during a workout for performance? 

For long, intense workouts, you may benefit from carbohydrates, electrolytes, and water. 

References

1. Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014 May;44 Suppl 1(Suppl 1):S25-33. doi: 10.1007/s40279-014-0148-z. PMID: 24791914; PMCID: PMC4008807.

2. Naderi A, Gobbi N, Ali A, Berjisian E, Hamidvand A, Forbes SC, Koozehchian MS, Karayigit R, Saunders B. Carbohydrates and Endurance Exercise: A Narrative Review of a Food First Approach. Nutrients. 2023 Mar 11;15(6):1367. doi: 10.3390/nu15061367. PMID: 36986096; PMCID: PMC10054587.

3. Adeva-Andany MM, González-Lucán M, Donapetry-García C, Fernández-Fernández C, Ameneiros-Rodríguez E. Glycogen metabolism in humans. BBA Clin. 2016 Feb 27;5:85-100. doi: 10.1016/j.bbacli.2016.02.001. PMID: 27051594; PMCID: PMC4802397.

4. Daghlas SA, Mohiuddin SS. Biochemistry, Glycogen. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539802/ 

5. Henselmans M, Bjørnsen T, Hedderman R, Vårvik FT. The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review. Nutrients. 2022 Feb 18;14(4):856. doi: 10.3390/nu14040856. PMID: 35215506; PMCID: PMC8878406.

6. Knuiman P, Hopman MT, Mensink M. Glycogen availability and skeletal muscle adaptations with endurance and resistance exercise. Nutr Metab (Lond). 2015 Dec 21;12:59. doi: 10.1186/s12986-015-0055-9. PMID: 26697098; PMCID: PMC4687103.

7. Henselmans M, Bjørnsen T, Hedderman R, Vårvik FT. The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review. Nutrients. 2022 Feb 18;14(4):856. doi: 10.3390/nu14040856. PMID: 35215506; PMCID: PMC8878406.

8. Triviño AR, Díaz-Romero C, Martin-Olmedo JJ, Jiménez-Martínez P, Alix-Fages C, Cwiklinska M, Pérez D, Jurado-Fasoli L. Acute effects of intra-training carbohydrate ingestion in CrossFit® trained adults: a randomized, triple-blind, placebo-controlled crossover trial. Eur J Appl Physiol. 2025 May;125(5):1337-1347. doi: 10.1007/s00421-024-05689-8. Epub 2024 Dec 13. PMID: 39671024.