Intra-workout Carbs: A Powerful Performance Booster or Recipe for Nausea?

If you’ve spent any time watching YouTube or TikTok videos of people strength training, you’d have realized that most people eat, like, a lot, in the gym. During their workouts. Between sets.

And by “eating”, it’s not just in the sense of sweets, pre-workouts, or protein shakes, but actual food. That requires serious jaw work.

Examples: white bread, rice, and the occasional pizza 🍕

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The guy who eats at Gym…🤣 #fyp #bodybuilding #gym #fitness

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So, this begs the question: Can intra-workout carbs help you lift heavier or a given load for more reps? Or, in other words, are they a good idea? Should you join in the munching party?

To answer that, it’ll be helpful for you first to understand:

How your muscles get energy during exercise

So. You probably already know what your body gets from carbs. Glucose, which is your body’s — including your muscles’ — primary source of energy.

Given that, it’s only natural to assume that intra-workout carbs would enhance performance. More carbs = more energy … right?

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Not necessarily.

See, your muscles rely on 3 metabolic pathways to generate adenosine triphosphate (ATP) or the “energy currency” of your body:

1️⃣
Phosphagen pathwayYour body uses creatine phosphate to re-form ATP in the muscle.While this offers the benefit of a rapid rate of ATP production, there’s limited stored creatine phosphate, which means your body usually exhausts the phosphagen pathway in ~30 seconds.(Sidenote: creatine supplementation bulks up your creatine phosphate stores, enabling your body to tap on the phosphagen pathway for longer. This enhances athletic performance.)

More on creatine here:

Ultimate Guide To Creatine And Its Benefits
Wondering if creatine is worth your money? Here’s everything you need to need about it - including its benefits, dosage, and side effects - before buying.
Does Creatine Cause Hair Loss? Shockingly, Science Says No
Does creatine cause hair loss? Contrary to popular belief — and an oft-cited 2009 study — no. Understand how we got so mistaken in this article.
4 Surprising Benefits of Creatine You Didn’t Know About
Creatine: only good for enhancing athletic performance? Nope. Here are 4 non-sports-related creatine benefits that’ll see have you going, “Wha—?”
2️⃣
Glycolytic pathwayAn intermediate pathway between the phosphagen and oxidative pathway; uses glucose to form ATP anaerobically (i.e., in the absence of oxygen).Although this system kicks in relatively quickly, it isn’t very effective. It can only supply ~3 minutes’ worth of energy.
3️⃣
Oxidative pathwayRequires oxygen to convert glucose (and fat) to ATP. Kicks in “slowly”, but it’s the most efficient ATP-producing pathway. Your body relies on this for anything that lasts longer than several minutes.

Intra-workout carbs: generally not necessary

Hmm. At this point, it appears that the usefulness of intra-workout carbs depends on your training style.

If you train with strength in mind, where you stick to the 3-5 reps range, your body will likely get a large part of the ATP it needs from the phosphagen pathway.

Your individual sets are over relatively quickly.

No need for that extra boost of intra-workout carbs.

On the other hand, if you train with hypertrophy in mind, the longer working periods would typically force your body to tap on the glycolytic and potentially oxidative pathways, which require glucose.

Meaning, yes to intra-workout carbs?

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Eh. We’re all forgetting something important. Glycogen. That’s the stored form of glucose, and we all have a ton of it. OK, OK, I’ll admit “a ton” is an exaggeration, but we really do have quite a bit:

  • ~ 500 grams in muscles
  • ~100 grams in liver

While how long it takes for you to deplete your glycogen stores can vary according to the type, intensity, and duration of exercise, here are some general ranges:

  • Low-to-moderate intensity exercise: 90 to 120 minutes
  • High-intensity exercise: 20 minutes

In most cases, your usual hypertrophy-focused gym workouts would veer toward the “low-to-moderate” intensity range. (High-intensity exercise is more for cardio purposes — e.g., training your VO2.)

Learn more about HIIT here:

HIIT vs LISS: Is High-Intensity Better than Steady State Cardio?
Why jog for 1 hour when 1 minute of HIIT gives you the same benefits? True or false? Let’s look at research to end this whole HIIT vs LISS thing.

Bottom line? Unless you’re planning to work out for longer than ~ 90 to 120 minutes, you aren’t going to see much benefit from intra-workout carbs.

Research agrees.

Multiple studies have found that intra-workout carbs don’t enhance performance.

When would intra-workout carbs be helpful?

Of course, that’s not to say that you should never eat carbs during your workouts.

As mentioned earlier, they’d naturally be beneficial when working out for extended periods and/or performing HIIT (although whether you’d have the appetite for it is another matter).

Other scenarios where they’d be helpful include:

👉
When you haven’t had a bite all morning, and now it’s time for your workout (i.e., “accidental” fasted workout) — the intra-workout carbs would help give you a much-needed glucose boost
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Sidenote: is there a point in doing fasted cardio?

Can Fasted Cardio Give You Better Fat Loss Results?
Fasted cardio forces your body to tap into your fat reserves for energy — which means it’ll help you lose fat faster, right? Hmm. Answers here.
👉
Repeated days of strenuous, prolonged physical activity and training (research suggests you’d need to increase your carb intake to at least 50% of your daily calories; intra-workout carbs could help you “plug” any gaps)

On that note, the amount of carbs you should eat daily will depend on your physical activity, fitness goals, and what works best for you. This means it may take you some time to find a macronutrient split that helps you eat enough:

… without busting your daily calorie budget.

A helpful tip: log your food intake and workouts. Over time, you should be able to get a sense of what works best for you.

Looking for a food + workout tracker app? You’re in the right place.

Here’s a smart, AI-powered workout planner with nutrition tracking that’s right up your alley: the GymStreak app.

Check it out here:

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Workout Programming + Nutrition Tracking, Off Your Hands

*sigh of relief* We'll guide you through it all — step-by-step. Just download the app, and you'll be making progress toward your dream body like never before.

References

“Glycogen Depletion: Signs and Symptoms.” 8fit, https://8fit.com/fitness/glycogen-depletion-signs-symptoms-and-working-out/. Accessed 9 June 2024.

Grijota, Franscisco Javier, et al. “Acute Effects of 30 g Cyclodextrin Intake during CrossFit® Training on Performance and Fatigue.” Journal of Functional Morphology and Kinesiology, vol. 9, no. 1, Jan. 2024, p. 27. PubMed, https://doi.org/10.3390/jfmk9010027.

Kulik, Justin R., et al. “Supplemental Carbohydrate Ingestion Does Not Improve Performance of High-Intensity Resistance Exercise.” Journal of Strength and Conditioning Research, vol. 22, no. 4, July 2008, pp. 1101–07. PubMed, https://doi.org/10.1519/JSC.0b013e31816d679b.

Morrison, Scot, et al. “ENERGY SYSTEM DEVELOPMENT AND LOAD MANAGEMENT THROUGH THE REHABILITATION AND RETURN TO PLAY PROCESS.” International Journal of Sports Physical Therapy, vol. 12, no. 4, Aug. 2017, pp. 697–710.

Murray, Bob, and Christine Rosenbloom. “Fundamentals of Glycogen Metabolism for Coaches and Athletes.” Nutrition Reviews, vol. 76, no. 4, Apr. 2018, pp. 243–59. PubMed Central, https://doi.org/10.1093/nutrit/nuy001.

---. “Fundamentals of Glycogen Metabolism for Coaches and Athletes.” Nutrition Reviews, vol. 76, no. 4, Apr. 2018, pp. 243–59. PubMed Central, https://doi.org/10.1093/nutrit/nuy001.