LibGuides: Year 10 HPE: Energy Systems

Energy Systems

ENERGY SYSTEMS

In order for our body to function properly we require energy. They body uses three energy systems to create energy and these are split up into two classifications, Aerobic (with oxygen) and Anaerobic (without oxygen). The Lactic Acid and ATP-PC energy systems are both anaerobic systems, and the aerobic energy system is an aerobic energy system.
A game of touch is seen to be both Aerobic and Anaerobic, but mostly aerobic. A good way to put it is that the sport is an aerobic sport that consists of many Anaerobic activities. Touch is a high intensity sport which relies heavily on the three energy systems, the ATP-PC energy system, the lactic acid energy system and the Aerobic energy system. The ATP-PC energy system gives athletes a quick but strong burst of energy which lasts approximately 10 seconds before the lactic acid energy system takes over. This short burst of energy is good for touch and is utilised during a game if a player makes a break, or is running after a player who made a break. The Lactic acid system lasts approximately 40 seconds and is used in a game during quick repetitive rucks. The Aerobic energy system kicks in after about 40 seconds and can theoretically sustain the human body indefinitely.

It is essential that any training program for Touch Football specifically train these three energy system as they are all individually important factors when it comes to playing the sport, and will ensure that players play to the best of their ability, a program which doesn't train the energy systems effectively runs the risk of being an ineffective training program.

Alactacid (ATP/PC) Energy System

Source of Fuel – The alactacid energy system or ATP/PC (Adenosine Tri-Phosphate/Phospho-Creatine) energy system uses the ATP that is immediately available within the muscle cell (myocyte). As the ATP id broken down into ADP and P, the ADP reacts with the PC (without the presence of oxygen) in the myocyte to produce another ATP and C (1 ATP per PC).

Efficiency of ATP Production – The alactacid energy system (ATP/PC) has a very fast rate of ATP production, but has a very limited store of fuel. The PC runs out quickly resulting in this system no longer being available until it has begun to recover.

Duration that the system can operate – The alactacid energy system (ATP/PC) does not last very long due to the limited fuel source and fast ATP production. The alactacid system will deplete its fuel in 8 seconds when used at maximal intensity, but can take as long as 12 seconds if used at a lower intensity.

Cause of fatigue – Fatigue in the alactacid energy system (ATP/PC) is caused by the depletion of fuel. Once the immediate stores of ATP and PC run out the system needs to recover before it can be used again.

By-products of energy production – The alactacid energy system (ATP/PC) has no by-products other than heat, which is a by-product of every energy system.

Sourced from http://www.unm.edu

Process and rate of recovery – The alactacid energy system (ATP/PC) recovers as the creatine in the cell connects to the free phosphates again, storing them as PC to be used when they are needed again. This process takes up to 2 minutes for complete recovery, but can be half restored at around the 30 second mark.

Examples – Due to the speed of ATP production and the short duration of the fuel source the alactacid energy system (ATP/PC) is the dominant system in activities such as a 100m sprint, discus, javelin, high jump and other sports of very short duration. However the alactacid energy system (ATP/PC) is also used to provide brief periods of high intensity within many other sports. Examples include kicking a ball during soccer or rugby league, or a short sprint where maximal effort is needed, but lasts only 5-10 seconds.

Lactic Acid system

Source of Fuel – The lactic acid energy system uses carbohydrates (CHO) as its only source of fuel

sourced from www.vivajoyhealth.com
sourced from www.vivajoyhealth.com

and relies on anaerobic glycolysis for its production of ATP. Glycolysis is the breakdown of glucose to produce ATP. In anaerobic glycolysis the glucose (sourced from glycogen in the muscle or glucose in the blood) is turned into lactic acid as it produces ATP.

Efficiency of ATP Production – This system produces ATP at a fast rate and can produce a lot of ATP. The lactic acid system produces 2 ATP for each glucose molecule it breaks down, however, it also produces lactic acid in the process.

Duration that the system can operate – The lactic acid system lasts between 30 seconds and 3 minutes depending on the intensity. The less intense the activity the longer it will last, because it will be producing lactic acid at a slower rate at the lower intensity levels.

Cause of fatigue – The cause of fatigue in the lactic acid system is the build up of pyruvic acid in the muscle. Pyruvic acid is made up of two molecules; pyruvate and a hydrogen ion (H+). Without oxygen the body converts the pyruvate and two H+ to lactate. This helps to reduce the acidity of the muscle and allows anaerobic glycolysis to last longer, as the lactate is removed from the muscle and taken to the liver where it is converted to a useful fuel source such as glucose. However, in continued high intensity activity the lactate cannot be removed fast enough, which results in a build up of pyruvic acid. It is specifically the build up of the H+ within the muscle that causes fatigue. It does this by increasing the acidity of the muscle and causing the enzymes needed for anaerobic glycolysis to slow down.[1]

By-products of energy production – The main by-product of the lactic acid system is pyruvic acid (pyruvate and H+). This by-product is then converted to lactate and transported out of the muscle to the liver to be converted to glucose.

Process and rate of recovery – The process of recovery once fatigue has occurred requires oxygen. Pyruvic acid in the presence of oxygen will be converted to acetyl coenzyme A, which is then broken down through the Krebs cycle to produce more ATP. Without oxygen it is converted to lactate and removed from the muscle and taken to the liver to be converted into glucose. This process can take anywhere between 30 and 60 min.

Examples – The lactic acid energy system is the dominant system in sports, which require a high intensity for longer than 10 seconds. Sports such as 200m or 400m run, or 50m and 100m swim are highly reliant on the lactic acid system. Other times when it is used would include repeated high intensity activities during other sports such as tennis running back and forth with small breaks in-between, repeated tackles in rugby or an extended piece of high intensity in any other sport such as a full-back going forward in an attack and then having to retreat in soccer.

[1] http://www.ptdirect.com/training-design/anatomy-and-physiology/the-aerobic-system

http://www.iaaf.org/download/downloadnsa?filename=3d668f8f-fedc-4bb7-b5f0-346c09f2bd17.pdf&urlslug=terminology-the-lactic-acid-system

Aerobic System

Aerobic Energy System
Sourced from www.zentofitness.com

Source of Fuel – The aerobic system can use CHO, fats, and protein as its source of fuel, though protein is used sparingly. The aerobic system uses aerobic glycolysis, the Krebs cycle and the electron transport chain in its production of ATP. It is the presence of oxygen, which allows this energy system to use these various fuel sources.

Efficiency of ATP Production – The aerobic system is very efficient in producing ATP. It produces 38 ATP molecules per glucose, but the
rate of production is medium and cannot cope with the higher intensity levels.

Duration that the system can operate – This energy system can produce ATP continuously for well over an hour. In fact, it may not have a limit as long as fuel sources can be found (you will die if this energy system cannot be used). However, your muscle glycogen will deplete after about an hour of exercise, which will result in an increased need for oxygen as fats becomes the dominant fuel source and uses more oxygen per ATP produced than CHO.

Cause of fatigue – Though this system does not need to stop, a reduction in intensity will occur when CHO stores deplete. Since fats require more oxygen to produce ATP than CHO, an athlete will normally decrease their intensity when their main fuel source switches from CHO to fats. This is often called hitting the wall. If it is possible for the athlete to transport oxygen at a faster rate than they are when their CHO run out, then their body will adjust and bring the extra oxygen to the muscle. This will mean an increase in respiration and possibly an increase in heart rate and cardiac output, but it will allow the athlete to continue to perform.

By-products of energy production – The aerobic system produces water and carbon dioxide as by-products in its production of ATP. Water can build up in the muscle and cause stiffness and a sort of “swelling” if exercise is continued at a high enough intensity for long enough, but generally it is transferred out of the muscle and into the blood as water is being lost through sweat during exercise. The carbon dioxide is taken out of the muscle and expired by the lungs into the atmosphere. Carbon dioxide, if not removed can cause fatigue, but is normally removed well.

Process and rate of recovery – Recovery for the aerobic system is about restoring fuel stores to their pre-exercise levels. This requires the ingestion, digestion and transportation of the fuel and can take between 12 and 48 hours depending on the intensity and duration of the aerobic performance.

Examples – The aerobic system is the dominant system for any sport or activity that lasts more than 3 minutes. This includes most team sports such as netball, soccer, rugby, and AFL as well as many individual sports such as 1500m swimming, marathon running, cycling, triathlons, tennis and iron mans.