How to Fuel Correctly During Intense Endurance Exercise?

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Your athletic performance is directly linked to the efficiency of your fueling during exercise.
How to Fuel Correctly During Intense Endurance Exercise

If you want to achieve top athletic performance, you need to learn how to use dietary supplements to sustain the required intake of carbohydrates during intense endurance exercise.

Be it energy gelsisotonic sports drinks, or other sources of carbs, optimal fuel is necessary to provide high levels of energy and preserve your glycogen stores as long as possible.

In this blog, you'll learn the importance of proper fueling and how to do it correctly.

A proper diet

Endurance and professional athletes know how important proper fueling is to achieve great results over an extended period of time. A distinguished sports nutritionist Asker Jeukendrup once said: “Proper diet can't make an average athlete elite, but a poor diet makes an elite athlete average.”

Even amateur athletes realize sooner or later they need to provide proper food to their body if they want to maintain a consistent training routine and keep progressing over time.

The Nduranz Carbohydrate Ratio (1:0.8 ratio of maltodextrin and fructose) allows you to maximize energy availability and ingest up to 90 grams of carbohydrates (360 calories) per hour without causing digestive issues.

It’s pretty simple on the surface: consume carbohydrates before exercise to provide body energy, and consume protein after exercise to stimulate muscle growth and recovery. Throw some healthy fat in there, because they are supposed to be essential to our health. Calculating calories also makes sense, but many people, including professional athletes, find it impractical, imprecise, and/or redundant.

Proper dieting can be either extremely complex or very simple. The truth is, as much as we’d all wish science could serve us the ultimate answer on a silver platter, we are still only scratching the surface of how our body uses all the macro and micronutrients at its disposal, and how they all interact with each other.

One of the things that is less known and explored, especially for amateur athletes, is fueling during exercise. Perhaps the reason is that most people don’t exercise hard enough to warrant additional fueling, or perhaps they think drinking an isotonic drink or regular water is all their body needs to get through a training session.

Glycogen Stores

The most important energy source during exercise are carbohydrates, namely glucose and glycogen. In relatively simple terms, glycogen is a branched chain of glucose molecules that we have stored in our muscles and the liver to fuel our energy demands when there is no glucose being absorbed from the gastrointestinal tract.

When there is no glycogen or glucose available, the body can turn protein into glucose through a process called gluconeogenesis, and this is definitely not something we want – to lose muscle mass.

Nduranz Nrgy Unit fueling system
Our body is very smart, and very keen to survive. It is also very energy consuming. Because the body knows that, it does its best to never run out of energy.

Since the body cannot predict when and what kind of food will be available to it (especially in nature food is a potentially very scarce resource), it stores energy for future use. The first amount of excess energy in the form of carbohydrates the body stores as glycogen in the liver and muscles, and when these stores are full, the body could in theory transform carbohydrates into fat.

Many modern people have problems with obesity. To put it simply, this is because we consume too much food, providing our body with much more energy than it is able to spend. In the developed world, there is an overabundance of food, but in the medieval times, obesity was considered a sign of wealth – and during a cold winter when food was scarce for all, obese people had a much greater chance of survival, as their bodies had large stores of energy available to them (like keeping money in a bank account).

While fat is a very smart way through which the body can store almost limitless amounts of energy, it is not a very efficient source of energy due to complex metabolic processes that need plenty of time and numerous enzymes. Moreover, if we want to use fats, we need oxygen, and there is lack of oxygen in our tissues during high intensity efforts.

Given that fat is abundant in humans, we mostly focus on getting the carbohydrate intake right – because depleting carbohydrate stores will unavoidably lead to fatigue, as we cannot utilize fats at the same rate as we can carbohydrates.

Fueling during exercise

The body loves its glycogen stores, just like most people love money in their bank accounts. Why? Quite naturally, because it makes it feel safe. Glycogen is stored in close proximity to the muscle fibers and is thus readily available to be used. Why bother using fats that need to come from adipose tissue? As time progresses and glycogen stores start to decline, we slowly increase fat oxidation rates, but we never cease to use carbohydrates. And when we run out of carbohydrates, we simply stop due to fatigue.

During exercise, especially intense exercise, our body burns through its glycogen stores fairly quickly. Athletes store from 300 to 600 grams of glycogen in their bodies, which fuels them for 90 to 150 minutes of high intensity exercise. So, in about two hours, we’ve run out of all the energy the body has readily available at its disposal. At this point we either stop or need to drastically reduce the intensity, and neither option is what we want.

But it doesn’t end here. Depleting our glycogen stores has several other downsides attached to it as well.

Once we run out of glycogen, the body might get the brilliant idea to start looking for energy elsewhere. And where could it look? If fat is not available, muscles look quite tasty, don’t they? Hack, sometimes the body might go after muscles even when there is plenty of fat lying around.

Finally, letting the body run out of its natural resources, i.e., glycogen stores, will negatively impact muscle recovery and increase the chance of injury. Our ability to perform over a longer period of time will drop severely, perhaps to the point of complete inactivity either because of long-lasting fatigue or because our body will simply break down and succumb to an endless series of injuries.

Fueling up

Whether we are professional endurance athletes or amateur athletes simply trying to maintain a decently active lifestyle, we want to keep our bodies fueled and our glycogen stores locked and loaded. In turn, our body will run smoothly, recover efficiently, and keep our muscles steadily growing. Our stress hormones will be under control and our physical performance will not only improve but keep improving over a prolonged period of time.

Now that we are clear on this, we should ask the simple question – how do we do that?

On the surface, it’s pretty simple. Our body gets glycogen from carbohydrates, so to replenish our glycogen stores, we need to consume the right amount of carbohydrates. And what is the right amount, you ask? Well, that depends.

The Nrgy Unit

To simplify the life of endurance athletes and all people involved in sports who wish to keep carbohydrates readily available, we have devised a simple on the surface yet deceptively sophisticated system which allows us to fuel during exercise in a manner that is easy and clear but also accurate and efficient.

This fueling system is based on a unit of energy we named Nrgy Unit.

The Nrgy Unit is designed to provide the best type of fuel to your body in the right amount and right combination while keeping everything as simple as counting to two.

One Nrgy Unit = 45 grams of carbohydrates = 180 calories 

Nrgy Unit fueling system

To determine exactly how many Nrgy Units you need, check out our fueling calculator!

Nrgy Unit Drink & Nrgy Unit Gel

The most efficient way to fuel during exercise is either with sports drinks or energy gels. Nrgy Unit Drink and Nrgy Unit Gel are both based on the Nrgy Unit system, so you can freely mix and match the two and be fully aware of your exact caloric intake.

Nrgy Unit Drink and Nrgy Unit Gel are based on the 1:0.8 ratio of maltodextrin and fructose. This ratio has been confirmed by the renowned nutritionist Professor David S. Rowlands and his team to be the most efficient combination of carbohydrates to be ingested during exercise.

Glucose and fructose use different transporters from the intestine to the bloodstream, which means the body can absorb more energy if both transporters are used simultaneously. Consuming only glucose (e.g., maltodextrin) or only fructose is like having two roads available, but only one road is full of traffic, while the other one is empty. The 1:0.8 ratio is the optimal ratio because it exploits both paths to their fullest potential.

The Nduranz athlete

Being able to maximize the intake of carbohydrates during exercise is a big deal. While an amateur athlete will need some dedicated testing to realize proper fueling improves their performance, professional endurance athletes depend on proper fueling to get them through the day.

The Nrgy Unit, based on the 1:0.8 ratio of maltodextrin and fructose, allows athletes to consume up to 90 grams of carbohydrates or 360 calories per hour, which equals two Nrgy Units, without causing digestive issues, which is the reason why this ratio is so powerful and why the Nrgy Unit system is such a phenomenal tool.

Dr. Tim Podlogar, the scientist and athlete behind the Nrgy Unit system, comments on the chance of increasing the intake to three Nrgy Units per hour, something only the most intense endurance athletes could ever need: “While the optimal maltodextrin to fructose ratio has received lots of attention already, we are still lacking understanding on what the upper limit for the intake of carbohydrates during exercise is. In my view, stronger, bigger, and better athletes could be ingesting and subsequently utilizing larger amounts of carbohydrates than the currently recommended 90 grams per hour. However, this is still merely a speculation, and we scientists are working hard to answer this question.”

Three Nrgy Units


To function properly during physical activity, our body needs fuel. This becomes increasingly important with the intensity and frequency of our exercise. The right type of fuel allows us to consume more carbohydrates, which means more calories and ultimately more energy.

The 1:0.8 maltodextrin to fructose ratio found in Nduranz products is optimal for the absorption of carbohydrates and allows us to keep carbohydrates readily available without digestive issues.

The Nrgy Unit represents 45 grams of carbohydrates, which equals 180 calories. Nrgy Unit Drink and Nrgy Unit Gel are both based on the Nrgy Unit, which allows us to consume a sufficient amount of calories as freely and efficiently as possible. 

The amount of Nrgy Units we need depends on the intensity of our exercise, but one Nrgy Unit should be enough for most physical activities, while two Nrgy Units are meant for high-intensity exercise.

One Nrgy Unit = 45 grams of carbohydrates = 180 calories = 1 hour of moderate intensity exercise

Nrgy Unit fueling system


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