The Three energy systems
The Adenosine Triphosphate System
The ATP PC system is the simplest system within the body. It is the anaerobic energy system that utilizes ATP stored in the muscle to create energy. ATP is comprised of adenosine and three phosphate groups. When energy is required for muscular work the brain sends nerve impulses to stimulate the required muscles and a chemical reaction occurs which ATP is then split at the third phosphate molecule and energy is released into the body. The chemical energy that has been released stimulates muscle fibres and therefore making that specific muscle contract. To replenish the ATP, the Creatine phosphate also has to split to release the energy and is then joined back onto the ATP molecules to replenish this energy source (Paul Rogers, 2010).
It does this with the use of fuel from food. After the ATP is has been used, Creatine phosphate is then needed to rephosphorylate ADP into ATP. Energy from food is required to fuel the replenishment of ATP stores. These food sources are Carbohydrates, Fats and proteins. Without these sources of fuel, the body wouldn’t function because ATP is used in muscle contraction and that happens with even the simplest of movements. As the fastest way to resynthesise ATP is with the CP system, this system is the predominant energy system used for all-out exercise lasting up to about 10 seconds (Idea, 2015). Activities that last 10 seconds could be boxing, or running at fastest speed possible for 50- 100m. The CP stores in the muscle can be resynthesised during low-intensity exercise or at rest. It takes several minutes to fully restore CP stores and with adequate rest in between high intensity movements, CP should be replenished between 3-6 minutes. However, since there is a limited amount of stored CP and ATP in skeletal muscles, fatigue occurs rapidly and a change in energy systems is required if the duration is prolonged over 10 seconds of 95-100% intensity work.
Glycosis System (Lactic Acid)
The next energy system that is put into place is the lactic acid system or otherwise known as the Glycolosis system. This system is anaerobic and oxygen is absent but the system does require carbohydrates. Carbohydrates are found in foods and are digested by the body and converted into glycogen which is then stored within the muscles. Following the initial 10 -12 seconds of maximal exercise with the ATP system, PC stores are exhausted and ATP still needs to be produced to provide energy. The body needs to find an alternate fuel and the lactic acid system becomes the dominant supplier of ATP when all resources of ATP and CP are depleted. Glycolysis is the breakdown of Carbohydrates (in the form of Glucose or Glycogen) into Pyruvic acid and resulting in the production of two ATP molecules (Paul Rogers, 2010).
A total of 10 chemical reactions are required to convert Carbohydrates into Pyruvic acid. The effect of the carbohydrates being produced into energy is that because no oxygen is present, it creates a bi product called Pyruvic Acid, which then forms into lactic acid, causing fatigue among the muscles and eventually a lack of intensity. If the lactic acid isn’t cleared from the muscles it accumulates and could cause the athlete to have to stop because of the fatigue and lack of an energy source present. The lactic acid system is an important energy system because it provides a very quick supply of ATP for intense, short bursts of activity (usually 30-60 seconds, but can last up to 3 minutes). The lactic system is used in a number of sports that do repeat sprinting or high energy activities, such as sprint cycling, 100m swim, soccer and up to the 400 meters in track. The duration of the system depends upon the intensity of the activity, therefore the less intense the activity, the longer it will last. For the energy systems to be in the lactic acid zone, the athlete’s heart rate must be over 85% of their maximum heart rate. This system has a fast production of ATP but doesn’t have the density in which they are normally produced in the CP system. Density meaning the amount of ATP produced.
The Aerobic System
Physical activity lasting more than a few minutes requires the presence of oxygen. This system is called the Aerobic system. Oxygen is not immediately abundant to the muscles when we begin exercise; rather, it gradually becomes available as the oxygen-rich blood fills the muscle cells (HSC, 2015). This allows the third energy pathway, called the aerobic pathway to become the predominant supplier of ATP. This process of fuel degradation is sometimes called aerobic metabolism. The fuel used for this activity is mainly a mix of carbohydrates and fats and sometimes the use of proteins. The aerobic system is extremely efficient in metabolizing fuel and providing energy. It produces large, almost unlimited amounts of ATP however chemical reactions are slow due to the necessity of oxygen to be present and the intricate chemical pathways involved. Compared to glucose, fats can supply up to 10 times as many ATP molecules in the body. Carbon dioxide is breathed out during the process of respiration and the water is available to the cells or is lost through sweat or expiration, hence why a person’s body sweats and feels hot to touch. Lactic acid does not accumulate during aerobic metabolism because oxygen is present. Typically the aerobic system would be used in a long distance runner or for a sport that goes for a long duration of time at a medium to low intensity.
Figure 1: This graph here shows the three different energy systems and the duration and intensity in which each one is used. As the graph shows, as the duration of the activity lengthens out, the intensity levels drop and the energy systems switch between each other depending on the intensity and duration of the activity.
The ATP PC system is the simplest system within the body. It is the anaerobic energy system that utilizes ATP stored in the muscle to create energy. ATP is comprised of adenosine and three phosphate groups. When energy is required for muscular work the brain sends nerve impulses to stimulate the required muscles and a chemical reaction occurs which ATP is then split at the third phosphate molecule and energy is released into the body. The chemical energy that has been released stimulates muscle fibres and therefore making that specific muscle contract. To replenish the ATP, the Creatine phosphate also has to split to release the energy and is then joined back onto the ATP molecules to replenish this energy source (Paul Rogers, 2010).
It does this with the use of fuel from food. After the ATP is has been used, Creatine phosphate is then needed to rephosphorylate ADP into ATP. Energy from food is required to fuel the replenishment of ATP stores. These food sources are Carbohydrates, Fats and proteins. Without these sources of fuel, the body wouldn’t function because ATP is used in muscle contraction and that happens with even the simplest of movements. As the fastest way to resynthesise ATP is with the CP system, this system is the predominant energy system used for all-out exercise lasting up to about 10 seconds (Idea, 2015). Activities that last 10 seconds could be boxing, or running at fastest speed possible for 50- 100m. The CP stores in the muscle can be resynthesised during low-intensity exercise or at rest. It takes several minutes to fully restore CP stores and with adequate rest in between high intensity movements, CP should be replenished between 3-6 minutes. However, since there is a limited amount of stored CP and ATP in skeletal muscles, fatigue occurs rapidly and a change in energy systems is required if the duration is prolonged over 10 seconds of 95-100% intensity work.
Glycosis System (Lactic Acid)
The next energy system that is put into place is the lactic acid system or otherwise known as the Glycolosis system. This system is anaerobic and oxygen is absent but the system does require carbohydrates. Carbohydrates are found in foods and are digested by the body and converted into glycogen which is then stored within the muscles. Following the initial 10 -12 seconds of maximal exercise with the ATP system, PC stores are exhausted and ATP still needs to be produced to provide energy. The body needs to find an alternate fuel and the lactic acid system becomes the dominant supplier of ATP when all resources of ATP and CP are depleted. Glycolysis is the breakdown of Carbohydrates (in the form of Glucose or Glycogen) into Pyruvic acid and resulting in the production of two ATP molecules (Paul Rogers, 2010).
A total of 10 chemical reactions are required to convert Carbohydrates into Pyruvic acid. The effect of the carbohydrates being produced into energy is that because no oxygen is present, it creates a bi product called Pyruvic Acid, which then forms into lactic acid, causing fatigue among the muscles and eventually a lack of intensity. If the lactic acid isn’t cleared from the muscles it accumulates and could cause the athlete to have to stop because of the fatigue and lack of an energy source present. The lactic acid system is an important energy system because it provides a very quick supply of ATP for intense, short bursts of activity (usually 30-60 seconds, but can last up to 3 minutes). The lactic system is used in a number of sports that do repeat sprinting or high energy activities, such as sprint cycling, 100m swim, soccer and up to the 400 meters in track. The duration of the system depends upon the intensity of the activity, therefore the less intense the activity, the longer it will last. For the energy systems to be in the lactic acid zone, the athlete’s heart rate must be over 85% of their maximum heart rate. This system has a fast production of ATP but doesn’t have the density in which they are normally produced in the CP system. Density meaning the amount of ATP produced.
The Aerobic System
Physical activity lasting more than a few minutes requires the presence of oxygen. This system is called the Aerobic system. Oxygen is not immediately abundant to the muscles when we begin exercise; rather, it gradually becomes available as the oxygen-rich blood fills the muscle cells (HSC, 2015). This allows the third energy pathway, called the aerobic pathway to become the predominant supplier of ATP. This process of fuel degradation is sometimes called aerobic metabolism. The fuel used for this activity is mainly a mix of carbohydrates and fats and sometimes the use of proteins. The aerobic system is extremely efficient in metabolizing fuel and providing energy. It produces large, almost unlimited amounts of ATP however chemical reactions are slow due to the necessity of oxygen to be present and the intricate chemical pathways involved. Compared to glucose, fats can supply up to 10 times as many ATP molecules in the body. Carbon dioxide is breathed out during the process of respiration and the water is available to the cells or is lost through sweat or expiration, hence why a person’s body sweats and feels hot to touch. Lactic acid does not accumulate during aerobic metabolism because oxygen is present. Typically the aerobic system would be used in a long distance runner or for a sport that goes for a long duration of time at a medium to low intensity.
Figure 1: This graph here shows the three different energy systems and the duration and intensity in which each one is used. As the graph shows, as the duration of the activity lengthens out, the intensity levels drop and the energy systems switch between each other depending on the intensity and duration of the activity.