Energy Systems: The three This article or section does

 Energy Systems: The three This article or section does

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Energy Systems This article is not intended to be a masterclass in biology or physiology, mostly because I am not the right person for that. However, it is a topic that I find very interesting, and that has helped me understand how my body demands and produces energy depending on the intensity of the exercise. So I'm going to tell you what it is about, and if you already want to go deeper into the subject, then better for you. Do not be overwhelmed if you read terms that are a bit technical, I only include them to give a little more precision to the article.

But why is it important to know what the three main energy systems of the human body are and how they work? Well, by general culture, it never hurts to know how we work, but, above all, to know how and from where our body gets energy when we exercise according to its duration and intensity. Energy systems, which are nothing more than the different ways in which the human body produces energy, can also be trained to be more efficient. So if we know how they work, our training plans will be better and accurate, as we will seek to optimize them for better performance. And in addition, we will be aware in the race of how we are spending the available resources of our body to obtain energy.

The human body is a wonderful and complex machine, that is clear to us. But like any machine, it also needs the energy to do work, technically speaking. Have you ever wondered where the energy comes from so that you can move an arm? Or take a step? Or scream? As it turns out, the human body has three main energy systems, or ways of producing energy: the phosphagen system (or immediate), the oxidative (or aerobic), and the glycolysis (or anaerobic) system. In the first place, it must be said that all these energy systems are always in operation, although one will predominate over the others depending on the type of activity, duration, and intensity. That is, one does not stop working and another starts up.

But how do these systems produce energy? For all use ATP Adenosine Triphosphate coming from (or adenosine triphosphate ), which is a molecule used by all living organisms as a primary energy source. The human body stores these ATP molecules, but in low and limited amounts, so it has to constantly replenish them. The faster the replenishment speed, the more efficient we will be energetically speaking. In this article I am not going to explain in detail how ATP is synthesized or used, I leave that to you in case you want to delve into the subject. But broadly speaking, we can say that what happens in our body is a chemical process on the ATP molecule called hydrolysis releases energy, producing a molecule of ADP (or Anedosine Diphosphate) as a result, which is then recycled by the body to transform it back into ATP. This process is known as the ATP / ADP cycle. But going back to the three energy systems mentioned above, how and when is each one more relevant?

The phosphagen system, or immediate

It is the system used in explosive exercises such as jumping, or a sprint, or weight lifting. It is the one that mainly supplies the energy Usain Bolt needs when he runs the 100 meters in less than 10 seconds. Or Lidia Valentin on a weight lift. It is called the immediate system because the obtaining of energy comes from the reserves of ATP and CP (Creatine Phosphate or Creatine Phosphate) stored directly in the muscle. Being stored in the muscle, this system does not have to resort to or process other slower sources, such as fat, to obtain ATP. The only problem with this system is that the ATP storage capacity in the muscles is very low. Of course, we can generate almost all the energy that is available at once in a high-intensity exercise of a maximum of 10 seconds. This system does not produce ATP but uses the one generated by the other two systems that we will see below.

The oxidative, or aerobic system

It is the main system that the human body uses to produce energy. It uses as fuel the carbohydrates, fats, and proteins that are available. It is a very efficient system because it does not produce waste during the process as does the anaerobic system, which we will talk about later. The mitochondria - and this is when I put on my biologist's coat - are the cells that are going to do the combustion, together with oxygen, to generate ATP. If you imagine mitochondria as in Once upon a time the human body, they would be like tiny power plants that are in the muscles.

Oxygen is the key for this system to work, hence its oxidative name. Surely you have heard endurance athletes, such as marathoners or cyclists, talk about VO2Max and other terms related to oxygen consumption, and above all that they say that the greater the capacity to consume and process oxygen, the better it will be for the patient. runner performance. Well,

they are talking about neither more nor less than the efficiency of the oxidative system to meet the energy demand without reaching the lactate threshold, which we will talk about now. The main objective in the training of endurance athletes is to increase the amount of oxygen that their bodies can obtain and process, thus improving the efficiency of their oxidative system. These pieces of training achieve an increase in mitochondrial density, that is, the number and size of mitochondria. And that makes sense, doesn't it? The larger the number and size of these tiny power plants, the greater the amount of energy that can be generated per minute.

As we increase the intensity, this system will provide more ATP to meet the demand, requiring more and more oxygen. But what happens when the energy demand is greater than the oxidative system can generate? Or put another way, what happens when we cannot inject enough oxygen into the system for the oxidative system to do its job? Well, we reach what is known as the lactate threshold, and the following energy system comes into play. The anaerobic system.

The glycolysis, or anaerobic system

When the oxidative system cannot produce more energy than is demanded due to lack of oxygen, hence the anaerobic name of this system, the body uses a "shortcut" called anaerobic glycolysis. to meet that demand. Putting it simply, what it does is produce the necessary ATP by converting glucose into lactate (or lactic acid). Under normal conditions, the body recycles lactate at a certain rate that varies from person to person. But when doing high-intensity exercise, above the lactate threshold, the rate at which lactate is created is greater than the rate at which it is reabsorbed, and it ends up accumulating in the muscles and blood. When lactate levels are very high, muscle fibers become acidic, which stop working properly, limiting their ability to exercise correctly.

A difference of this system concerning the oxidative system is that it can only use carbohydrates as fuel, and not fats or proteins. That is why you have heard that to burn fat you have to exercise below our lactate threshold or anaerobic threshold. Although that statement is not very precise because as I pointed out at the beginning of this article, the three energy systems are always in operation. Even when we exercise anaerobic we will be burning fat because the aerobic system continues to work. On the other hand, 

it would be correct to say that exercising above the anaerobic threshold is not recommended if the goal is to burn fat. But not because it does not burn fat, but because we will not be able to sustain the intensity of the exercise for a long time. And it is that the anaerobic system also has a limitation of approximately one minute when providing energy in a high-intensity exercise, such as a 400m run. From there, muscle fatigue due to the accumulation of lactate will limit the ability to perform the exercise. That is why exercise below the anaerobic threshold is better to burn fat, because we can do it for a longer time and, therefore, get the aerobic system to burn more fat.

Conclusions

I hope I did not let go of the role. In my opinion, it is important to know how my body produces and manages the energy it has available. This makes me more aware of why it is important to train the oxidative system and the glycolysis system, especially the oxidative one for trail running and cycling, which are the endurance sports I do.