Glycogen Depletion Workouts: What They Are & Why They Matter

Glycogen Depletion Workouts: What They Are & Why They Matter

Glycogen Depletion Workouts: Quick Summary

Glycogen depletion workouts help your body burn through stored carbs for energy.

They can help with:

• Improving insulin sensitivity
• Boosting endurance training adaptations
• Supporting fat metabolism when glycogen is low

Ideal for:

• Endurance athletes training for performance
• Those wanting to improve metabolic flexibility
• People looking to optimize carb usage and recovery

This guide explains:

• What glycogen is and how your body uses it during workouts
• How to know if you're actually depleting glycogen (hint: it's about intensity)

Learn the best ways to deplete glycogen through:

• High-intensity resistance training
• Long-duration cardio (30+ minutes above 180 – your age bpm)
• Sample workouts for upper body, lower body, and endurance

You know those workouts that take it all out of you? The ones where you’re left feeling beat. The ones where you want to fall over and nap afterward. The ones where you feel shaky.

These are just some of the feelings you might get from a glycogen depletion workout.

What is Glycogen?

Now, you may be wondering what glycogen is.

Glycogen is carbohydrates that your body stores in your muscles and liver. It's your body’s most readily available form of energy.

When you eat carbs, your body breaks them down into a simple sugar called glucose in the blood. The glucose that your body doesn't use for energy immediately is then stored as glycogen.

During high-intensity exercise and resistance training, your body uses glycogen. It breaks the glycogen down to glucose that it can use during exercise for energy.

So, when you run out of glycogen during exercise, you can feel like you've hit a wall. Plus, once your workout is over, you can feel absolutely drained. This would be a glycogen depletion workout.

The question is, are there benefits to these glycogen depletion workouts? What do glycogen depletion workouts look like? All of this and more, I'm here to walk you through today!

What Are Glycogen Depletion Workouts? 

Glycogen depletion workouts are workouts where you exhaust your body’s glycogen stores. It's really that simple.

However, I'll take it a step further. I would argue that glycogen depletion workouts are workouts you do with the intention of depleting your glycogen stores.

This can be high-intensity workouts, resistance training workouts, long endurance workouts, and more.

Regardless of what the workout is, the goal is to use all of your body's glycogen! Again, once this happens, you can feel extremely fatigued. But that's not the reason why people do them.

So, why do people do glycogen depletion workouts? What are the benefits?

Why Are Glycogen Depletion Workouts Beneficial?

High-intensity glycogen depletion workouts can offer quite a few different benefits. However, that doesn't mean they're necessarily better than other styles of training.

I would argue that there are two main ways that glycogen depletion workouts can be beneficial. I'll walk you through each real quick so you can decide whether these workouts make sense for you or not.

Glycogen Depletion Workouts Can Help Improve Insulin Sensitivity

Exercise in general has been shown to be beneficial for increasing insulin sensitivity (1). Insulin is the hormone your body releases to help manage blood glucose levels. 

With greater sensitivity, your body and muscles can more effectively use glucose and other nutrients. It can also help keep your blood sugar levels more stable throughout the day for more sustained energy.

In the case of glycogen depletion workouts, this benefit could be even greater. Some people use glucose disposal agents to help their body make the most of this improved insulin sensitivity.

Glycogen Depletion Workouts Can Be Beneficial For Endurance Athletes

For endurance athletes, glycogen depletion workouts could be particularly beneficial.

I'm talking about their training for competition specifically. It certainly wouldn't be the best idea to run a marathon or do an Ironman without carbohydrates.

So, why would it be beneficial to deplete glycogen stores for training purposes? Well, with low glycogen, your body can adapt and improve oxidative capacity (3).

Oxidative capacity is a measure of how efficiently your muscles can use oxygen. Basically, the higher the oxidative capacity, the better an endurance athlete can perform.

How To Know When Your Workouts Deplete Glycogen

Our bodies and muscles use different things for energy at different times. Our main fuel sources are carbs and fats, but we use them at different times and for different reasons.  

Carbs are used by your body for higher-intensity exercise. Fats are used for lower-intensity exercise. So, how do you know when you are depleting glycogen? 

When it comes to resistance training, you are depleting glycogen for energy. That's whether it’s at-home workouts, CrossFit, traditional lifting, or anything in between.

When it comes to cardio exercise or aerobic training, it depends. At lower intensities, your body will likely be using fats for fuel. But when does your body deplete glycogen for these workouts? 

You deplete glycogen in these workouts when they are high-intensity. The Maximum Aerobic Function Equation is one way that will tell you how you can use heart rate readings to see if you are using glycogen or fats for fuel. 

That equation is 180 - AGE. So for example, if you are 30 years old and your heart rate gets up to or above 150 bpm during your cardio workout, then you are likely using glycogen for energy (4). 

Even if you’re not always sure how to tell if glycogen is depleted, it’s useful to know which types of workouts rely on it the most.

Examples of Glycogen Depletion Workouts 

So, are you wondering how to deplete glycogen through workouts? There are many different ways that you can do glycogen depletion workouts. In my opinion, it's all about finding what you enjoy the most! Part of this could also involve which workouts will be most beneficial for your goals.

Here are two examples of glycogen depletion workouts you can try out now! I wrote one for your lower body, one for your upper body, and one for endurance.

Lower Body Glycogen Depletion Resistance Workout

Complete 3 rounds of the following exercises in rapid succession! Don't worry - You can take 1-2 minutes of rest between each round. You can also do these exercises with or without weights. Do what challenges you and is within your physical capabilities!

Exercise Reps
Sumo Squats 20
Reverse Lunges 20 Each Leg
Glute Bridge 20
Romanian Deadlift 20
High Knees 30 Each Leg
Butt Kicks 30 Each Leg
Jumping Squats 20

Upper Body Glycogen Depletion Resistance Workout

These are my favorite upper-body exercises to deplete glycogen stores. For this workout, you'll complete each exercise for a set number of reps and sets. Make sure you are choosing weights that make the last 2 reps a challenge!

Exercise Reps Sets
Incline Dumbbell Press 6-12 4
Close Grip Lat Pulldown 6-12 4
Push-Ups or Machine Chest Press 12-15 3
Seated Cable Row 12-15 3
Incline Dumbbell Fly 25 3
Straight Arm Lat Pulldown 25 3

Endurance Glycogen Depletion Workout

Obviously, this can look a lot different for each person depending on their fitness level. For me, running a half-marathon would be more than enough! For others, even biking that much could be too much.

Whatever you choose to do, I would aim to do it for 30+ minutes and keep your heart rate above your maximum aerobic threshold. For this, you'll have to refer back to the equation I gave you. 180 - AGE = A good estimate of your maximum threshold.

Reaching Your Goals with Glycogen Depletion Workouts

Glycogen depletion workouts can come with some great benefits, that's for sure. If you want to improve your health, gain muscle, or lose fat, there can be a time and place to use them.

So, how can glycogen depletion workouts help you reach your goals? That depends.

In most cases, glycogen depletion workouts won't be very relevant to helping you reach your goals. Unless you're an athlete who's really trying to maximize their performance, or you want to increase insulin sensitivity ... I would argue it's not necessarily worth keeping on your radar. Truthfully, you'd be splitting hairs at that point.

However, yes, workouts that deplete glycogen can be very beneficial in specific cases.

For example, if you want to lose fat or build muscle, resistance training is an excellent option. Even still, it's not an excellent option just because it depletes glycogen.

So, consider what your goals are. Because at the end of the day, glycogen depletion workouts are a very small piece of that equation. A lot of times, I would argue it's not even worth worrying about depleting your glycogen.

Your overall approach to exercise and nutrition is what matters more than anything else. Plus, that's where we can really help you out!

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References:

(1) Borghouts LB, Keizer HA. Exercise and insulin sensitivity: a review. International Journal of Sports Medicine. 2000;21(1):1-12.

(2) Margolis LM, et al. Exercising with low muscle glycogen content increases fat oxidation and decreases endogenous, but not exogenous carbohydrate oxidation. Metabolism: Clinical and Experimental. 2019;97:1-8.

(3) Knuiman P, et al. Glycogen availability and skeletal muscle adaptations with endurance and resistance exercise. Nutr Metab (Lond). 2015;12:59.

(4) Maffetone P, Laursen PB. Maximum Aerobic Function: Clinical Relevance, Physiological Underpinnings, and Practical Application. Frontiers in Physiology. 2020;11:296.

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