Energy systems: aerobic and anaerobic
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| Energy systems aerobic and anaerobic |
We often hear about energy systems carbohydrates and fats which are essential sources of energy, as well as proteins which, in training, play a crucial role in the recovery and growth of muscles. Behind these organic compounds is a whole mechanism that governs human muscle activity.
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It is first necessary to define certain terms and understand energy systems, that in the jargon of the medium, several equivalences are used. However, in the end, we will refer to one or other of the three energy systems that the body uses. Alactic anaerobic, also known as direct phosphorylation, is one of three systems that employ ATP (adenosine triphosphate) and creatine phosphate. (It is commonly called the “ATP-PCR” system.) We will then talk about anaerobic glycolysis, which mainly uses glucose, and finally about the aerobic system, which is the oxidative pathway of the body. If necessary, please refer to this paragraph or to the lexicon: the article is at the same time a kind of glossary which, I hope, will allow you to familiarize yourself with the different equivalences.
Small glossary before starting:
- Anaerobic: without the use of oxygen
- Aerobic: with the use of oxygen (reaction following cellular respiration)
- Lactic: with the appearance of lactate ( lactic acid )
- Alactic: Without lactic acid production
- ATP: Adenosine triphosphate
- ADP: Adenosine diphosphate
- CP: Creatine phosphate
emAlactic anaerobic / ATP-PCR syst
Let's define ATP:
Among athletes, we talk a lot about carbohydrates. It is both a necessity and the biggest demon of the century ... But even if glucose is a preferred form of energy for the body, it is not directly usable for reactions at the cell level. This is where ATP comes in. It is an adenine nucleotide to which phosphate groups are attached.
"What does that mean exactly in French?" "
A nucleotide is a basic unit of nucleic acids: there are several and adenine is one. Nucleic acids are the largest molecules in the body, formed in the heart of the cell, or in the nucleus. There are two categories: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) (Marieb: 62) Chemistry class ends here… Just understand that ATP is a functional unit of energy.
No matter what you ingest, ATP, which is considered to be the “energy unit of the cell” (Marieb: 1078), will be stored for most of the body's functional processes. The anaerobic lactic system uses the reserves of ATP and creatine phosphate, already present in muscle cells. We are talking about a system that feeds intense efforts that cannot exceed 10 seconds.
This is a system that works without the use of oxygen: be careful, don't get me wrong, breathe anyway! Without falling into a level of details that are difficult to digest, this basic energy molecule, ATP, is very unstable, due to its composition with three phosphate groups. It will hydrolyze and thus give an ADP molecule (adenosine diphosphate) and a free phosphate group. This ADP molecule thus obtained will bind to the creatine phosphate molecules that the body stores when we consume proteins. animal. Since the stores of CP are thin, the process of binding ADP molecules to intramuscular creatine phosphate will continually form new ATP molecules until the stores of creatine phosphate are depleted.
For example, the 100 meters event and weightlifting are activities that will use this energy system.
It's worth a little digression, as questions about the effect of creatine supplements often surface. Creatine, in supplementation, will increase the reserves of a substrate, creatine phosphate, which is involved in the reaction that produces new ATP molecules in combination with ADP.
The combination with training focused on relative strength will generate adaptations and make the anaerobic lactic system of the athlete more efficient. Thus, a weightlifter will improve his ratio of IIA and IIB fibres, which are more powerful fibres, compared to slow type I fibres. Also, his creatine phosphate reserves will increase, his glycogen reserves too; the vascularization of muscle fibres will improve, in short: the anaerobic system will be optimized.
Anaerobic glycolysis / the anaerobic lactic system
Glycolysis, glucose, glycogen?
This is when he turns to his glycogen stores.
Quickly, a reaction will follow which will transform the glucose molecules into ATP. As a result of several chemical reactions, the body will manage to produce 2 molecules of ATP for one molecule of glucose. The process still takes place without the intervention of oxygen, but the glycolysis reaction will generate the appearance of lactate molecules. This is where we will start to talk about lactic acid, which will eventually make the individual more tired and less efficient at exercise. With training, this lactic acid will then be "recycled" during the Cori cycle, but that is a bit beyond the scope of this article.
Anaerobic glycolysis will take place during intense efforts of average duration, varying from 10 seconds to two minutes. In hypertrophy for example, when we will apply intensification techniques, we will observe the impression of having shorter breaths and when the series will be spread over 40 to 70 seconds, we will speak of anaerobic lactic acid.
The aerobic system / oxidative phosphorylation
We have talked about two different systems that do not use oxygen. Before concluding with the body's oxidative system, which provides the majority of our daily activities as well as the moderate efforts of longer duration, it should be understood that the above systems, as well as the aerobic system, work simultaneously, but that one of the between them will predominate depending on the duration of the effort. When we put ourselves into action, the body activates three energy motors, which last more or less long depending on the task and the intensity of the effort. The aerobic system will start to gain the upper hand when activity exceeds one minute. Commonly, it is explained that aerobic is for an effort of 2 minutes to several hours. Up to 70 seconds of activity, the lactic system jointly produces energy; subsequently, the oxidative system, less powerful, but much more durable, takes over. When oxygen travels to the mitochondria, complex mechanisms called oxidative glycolysis and oxidative lipolysis are activated. At this time, the body still draws on glucose, but mainly on fatty acids.
It thus manages to produce 36 molecules of ATP for a single molecule of glucose and up to 129 molecules of ATP for a single molecule of fatty acid, depending on the number of carbons. Whether we are talking about a sedentary person performing household chores or a marathon runner, it is the aerobic system that is activated, with varying degrees of efficiency. An individual who has good cardiovascular endurance, and therefore a good VO2max (capacity for maximum oxygen consumption), will have an efficient oxidative system, considering that his muscles make better use of the inspired oxygen.
To summarize, three systems intervene during an effort of medium to high intensity: anaerobic lactic, then anaerobic lactic, and finally, aerobic.
From a more practical point of view, knowing these three energy pathways allows you to better manage your daily diet, knowing that it is possible to adapt the consumption of carbohydrates or lipids according to the level or type of activity and the time of the day. The protein, in turn, is also crucial to ensure muscular recovery. It also helps to forge links between the type of exercise you find in your training plan and the systems used. Moreover, a better analysis of the sport or activity that you practice will perhaps allow you to choose a more specific and adapted training to optimize one or the other of these three systems.
It's a very complex subject and the biochemical reactions that fuel energy production go beyond what I tried to make accessible, so I hope I was able to enlighten you and look forward to discussing with you!
nice post
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