Where do we get the energy to move? How do we use it?
It can get even worse when sifting through all the biochemical processes. However, knowing the basics of how we generate energy can be helpful in understanding how we fatigue and what training measures can be used to minimize it.
When an ATP molecule is combined with water the last of three phosphate groups splits apart and produces energy. On one end would be a quick, explosive burst such as throwing a punch. On the other end would be an extended, lower-level event such as walking five miles.
Between the two could be anything: As you can see, there are many expressions of energy output depending on the amount of force required and the length of the activity. What then, is the energy source for activities that fall on the continuum at various points?
This is the essence of bioenergetics - so many possibilities and so many factors involved. What dictates which one or two is relied upon the most is the effort required. ATP must be present for muscles to contract. If depleted, it must be replenished if further muscle contraction is to continue.
Perform an explosive, one-time movement such as a standing long Atp-pc energy system resynthesis or vertical jump and you exert maximal effort, but guess what? You will not become fatigued from this single exertion.
However, jump multiple times and eventually you will become fatigued. Going all-out for as long as possible will deplete immediate ATP stores, then glycolytic stores. Continuing effort must be fueled by the oxidative system at a lower intensity, all other factors being equal.
The most pure aerobic activity that exists is sleeping or lying comatose. It is immediate and functions without oxygen. During the first few seconds of any activity, stored ATP supplies the energy. For a few more seconds beyond that, PC cushions the decline of ATP until there is a shift to another energy system.
Dietary carbohydrates supply glucose that circulates in the blood or is stored as glycogen in the muscles and the liver. Like the ATP-PC system, oxygen is not required for the actual process of glycolysis but it does play a role with the byproduct of glycolysis: It is estimated glycolysis can create energy at approximately 16 calories per minute.
Here is where it gets interesting. After maximum power declines around 12 seconds, further intense activity up to approximately 30 seconds results in lactic acid accumulation, a decrease in power, and consequent muscle fatigue. Exerting further effort up to approximately 50 seconds results in another drop in power due to the shift in dependence on the oxidative system.
That is the progression of the three energy systems when going all-out. Recall the byproduct of glycolysis is pyruvic acid. In fast glycolysis, more power can be generated, but pyruvic acid is converted to lactic acid and fatigue ensues quickly.
Slow glycolysis is different. Relatively less power is generated, but pyruvic acid is converted to acetyl coenzyme A acAfed through the oxidative Krebs cycle, more ATP is produced, and fatigued is delayed.
Thus, extreme fatigue can be avoided but relatively less-intense effort can continue to be expressed in slow glycolysis as compared to fast glycolysis. Continued effort results in further decline, either via fast glycolysis quick decline or slow glycolysis slower decline. The effort demand is low, but ATP in this system can be produced three ways: Krebs cycle Beta Oxidation.
The Krebs cycle is a sequence of chemical reactions that continues to oxidize the glucose that was initiated during glycolysis. Here is the problem: Through more chemical reactions in the electron transport chain, hydrogen combines with oxygen, water is produced, and acidity is prevented.
Notice this takes time due to the need of oxygen, which is why the oxidative energy takes a while and intensity of effort declines i.
The Krebs cycle and the electron transport chain metabolize triglycerides stored fat and carbohydrates to produce ATP. The breakdown of triglycerides is called lipolysis.The ATP-PC energy system is the system by which the body fuels 10 to 20 seconds of intense exercise by using stored ATP, the high-energy molecule that fuels muscles, and then through phosphocreatine, which is quickly converted to ATP to further fuel muscle contractions.
There are two systems within Anaerobic metabolism, which are the ATP-PC system and the lactic Cellular Respiration is the process that takes place in cells.
The anaerobic glycolysis energy system produces energy by the breakdown of glucose in the absence of oxygen, Anaerobic Glycolysis: Process of ATP production. Training the ATP-PC Energy System.
To develop this energy system, sessions involving repeats of up to seconds of maximum intensity activity/work are required, with approximately two minutes rest between repeats to allow the system to replenish.
There is a more scientific formula for rest periods called the ‘work to rest ratio’. The Three Energy Systems. Conventionally, there are three energy systems that produce ATP: ATP-PC (high power, short duration), glycolytic (moderate power/short duration), and oxidative (low power/long duration).
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As the name suggests the ATP-PC system consists of adenosine triphosphate (ATP) and phosphocreatine (PC).
This energy system provides immediate energy through the breakdown of these stored high energy phosphates. ATP resynthesis is the process by which the body and its muscles produce ATP. ATP is the main energy source of almost all living things, and while ATP is not energy itself, it temporarily stores energy in its bonds to be released on demand.
Humans resynthesize ATP through three metabolic pathways.