Fitness Friday - Time Domains Part 1 The Science

In fitness, it's always great to know how you should train to get the best results possible for your goals. In fitness, there are a lot of variables that dictate what benefits you will get from different styles of training and how long you really need to train to get the results that you want.


In this post, I am going to go through different time domains and what energy systems are used to produce energy. I will also give you a basic understanding of how they produce energy and how long each system works for.


To start I am going to break down the basic time domains and what energy systems they use to produce energy. Then I will go through each system and discuss how they use energy.


The three main time domains are.


Short - 0 seconds to 90 seconds. This time domain utilises the creatine phosphate system and starts to transition into the anaerobic system.


Medium - 90 seconds to 5 minutes. This time domain uses the anaerobic system to generate the energy. It starts to transition into the aerobic system.


Long - 5 minutes onwards. This is all the aerobic energy system.


So far I have given out names of a few energy production systems in the body but not explained how they work or how they are used. In your body, you use a chemical called ATP(Adenosine Triphosphate.) During the breakdown of ATP, your body produces energy, the energy causes movement in the muscles. The speed at which ATP breaks down is the speed that energy is produced. So during the different systems that create energy for movement, the faster ATP is produced and broken down the more force will be created for that moment.


The creatine phosphate system is the bodies way of producing energy out of the stores of ATP in your muscles. Because of this, the breakdown ATP is very rapid and cause a very powerful muscular movement. This is why the creatine phosphate system is used for strength or speed movements but only last for a very short period of time.


The anaerobic system uses glucose or glycogen to produce ATP. Once the stores of ATP in the muscle are used up the body has to find another way to produce ATP and it does this by breaking down glucose or glycogen to form ATP. This method does not involve the use of oxygen and because of this, it forms a by-product called lactic acid. When lactic acid builds up in the body it creates a burning sensation in the muscles. This burning sensation makes it so that the body can only sustain high levels of the moment for a short period of time. The anaerobic system can create a high level of force out of the muscles for a longer time domain that the creatine phosphate system but not with quite as much force.


The anaerobic system is technically the glycolytic system because of its use of glucose and glycogen to make energy. Because of this both the glycolytic and creatine phosphate systems are classed as anaerobic systems. They can produce ATP without the presence of oxygen but only for short periods of time.


The last system used for the long time domains is the aerobic system. This can also be called the oxidative system. This system uses carbohydrates, fats and proteins in the body with the presence of oxygen to create ATP. This system can be used for long durations of time and can be conditioned to improve the more you use it. This system can only produce limited amounts of power out of the muscles as the speed that it produces ATP is produced is a bit slower but because of this, there is a lot less lactic acid produced.


When using the aerobic system there are still quantities of lactic acid that are produced and this can increase or decrease depending on the amount of muscle recruitment an exercise uses. The faster you move the more lactic acid is produced, the faster you burn out.


I hope that this post has made it a bit easier for you to understand how each time domain is affected by different body energy production systems. In next weeks post, I will go through how you can develop each system and how you can train different systems in tandem to become a better athlete.

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