Energy Systems Flashcards
What does ATP stand for?
Adenosine triphosphate
What is ATP composed of?
1 molecule of adenosine and 3 phosphates
What are the names of the three energy systems?
The aerobic system
The ATP-PC system
The anaerobic glycolytic
What are the three stages of the aerobic energy system?
Glycolysis
Krebs cycle
Electron transport chain
Describe the process of glycolysis.
Glycolysis occurs in the sarcoplasm of muscle cell and is the breakdown of glucose into pyruvic acid. For every 1 molecule of glucose broken down 2 molecules of ATP are formed.
Describe what happens after glycolysis to pyruvic acid before it can enter the Krebs cycle.
The pyruvic acid is oxidised into two acetyl groups and is carried into the Krebs cycle by coenzyme A.
Describe the process of the Krebs cycle.
The two acetyl groups diffuse into the matrix of the mitochondria. Here the acetyl groups combine with oxaloacetic acid to form citric acid. Then hydrogen is removed from the citric acid and the acid undergoes oxidative carboxylation (carbon and oxygen are given off). The carbon dioxide given of forms carbon dioxide which is transported to the lungs and breathed out. The hydrogen given off is taken to the electron transport chain. This cycle produces 2 molecules of ATP.
Describe the process of the electron transport chain.
Hydrogen is carried into the hydrogen transport chain by hydrogen carriers. this process occurs in the cristae of the mitochondria. During this process, the hydrogen splits into hydrogen ions and electrons. The hydrogen ions are oxidised to form water, the hydrogen electrons provide the energy to resynthesise ATP. This process produces 34 ATP molecules.
What is beta-oxidation?
Beta-oxidation occurs after stored fat is broken down into glycerol and fatty acids. After this happens beta-oxidation occurs, the fatty acids are converted into acetyl coenzyme A which then enters the Krebs cycle.
What are the advantages of the aerobic system?
36 ATP molecules are produced
No fatiguing by-products are produced
Lots of glycogen and fats stores in the body so exercise can last a long time
What are the disadvantages of the aerobic system?
It takes a while for enough oxygen to become available
The transportation of fatty acid to muscles is low and requires 15% more oxygen to be broken down than glycogen
What kind of exercise is the aerobic system used in?
Low intensity, long duration, aerobic exercise such as marathon running.
What is the ATP-PC system?
This energy system uses phosphocreatine as the fuel. It is an anaerobic process and re-synthesises ATP when creatine kinase detects high levels of ADP. When high levels of ADP are detected phosphocreatine is broken down into phosphate, creatine and energy. the phosphate and energy given off by this reaction are used to re-synthesised ATP. For every molecule of phosphocreatine broken down 1 molecule of ATP is formed.
What are the advantages of the ATP-PC system?
ATP is rapidly re-synthesised
Phosphocreatine stores can be re-synthesised quickly
There are no fatiguing by-products
The duration of the system can be increased through the use of creatine supplements
What are the disadvantages of the ATP-PC system?
There is a limited supply of phosphocreatine
Only 1 ATP molecule is re-synthesised per phosphocreatine molecule
The re-synthesise of the phosphocreatine stores can only occur in the presence of oxygen
What kind of exercise is the ATP-PC system used in?
High intensity, short-duration exercise. This system produces enough energy for 5-8 seconds so this energy system is good for events like 100m sprints.
What is the anaerobic glycolytic system?
When phosphocreatine systems are low the enzyme glycogen phosphorylase is activated to break down the glycogen into glucose which is then further broken down into pyruvic acid. This process takes place in the sarcoplasm of muscle cells when oxygen is not available. Because this is an anaerobic process the pyruvic acid is further broken down into lactic acid.
What are the advantages of the anaerobic glycolytic system?
ATP can be re-synthesised quickly
What are the disadvantages of the anaerobic glycolytic system?
Lactic acid is a by-product produced which denatures enzymes.
Only a small amount of energy is released.
What kind of exercise is the anaerobic glycolytic system used in?
Used during exercise of high intensity over a short duration. This system lasts up to 2-3 minutes.
How is energy generated in slow-twitch muscle fibres?
The main pathway of ATP production is the aerobic system
It produces up to 36 ATP molecules
ATP production is slow
How is energy generated in fast-twitch muscle fibres?
The main pathway of ATP production is the anaerobic glycolytic system
It is not very efficient (only 2 ATP molecules produced)
Very fast ATP production but these fibres fatigue very quickly
What is oxygen consumption?
The amount of oxygen we use to produce ATP (VO2)
What is VO2 max?
The maximum volume of oxygen that can be taken up by the muscles per minute.
What is sub-maximal oxygen deficit?
When there is not enough oxygen available at the start of exercise to provide all the energy aerobically.
What is excess post-exercise oxygen consumption?
When exercise finishes oxygen consumption remains quite high compared to oxygen consumption at rest. This occurs because extra oxygen is required to help the performer recover. This is what causes the breathlessness after exercise
What are the two components to EPOC?
The fast component (alactacid component)
The slow component (Lactaid component)
What is the fast component?
The restoration of ATP and phosphocreatine stores and the re-saturation of myoglobin with oxygen.
What is the slow component?
The removal of the lactic acid that accumulates in the muscles during recovery. Full recovery may take up to an hour or longer depending on the intensity and duration of the exercise.
How can lactic acid be removed in the slow component?
When oxygen is present lactic acid can be converted back into pyruvate and oxidised into carbon dioxide and water.
Transported in the blood to the liver where it is converted to blood glucose and glycogen
Converted into protein
Removed in sweat and urine
What happens during a short duration/high-intensity exercise?
The aerobic system is to complex to be used during this form of exercise, therefore the ATP PC system and the anaerobic glycolytic system is used.
What is lactate?
Lactate is produced when lactic acid is broken down causing hydrogen ions to be released. The remaining product of this is combined with sodium ions and potassium ions.
What happens during lactate accumulation?
As lactate accumulates in the muscles more hydrogen ions become present. these hydrogen ions increase the acidity which slows down enzyme activity causing muscles to fatigue.
What is the lactate threshold? Lactate threshold and OBLA are different ways of measuring the same thing
The lactate threshold is the point during exercise at which lactic acid quickly accumulates in the blood. The fitter an individual the longer it takes for them to reach their lactate threshold.
What is OBLA? Lactate threshold and OBLA are different ways of measuring the same thing
OBLA is the point at which lactate levels go above 4 millimoles in the blood. At rest, we normally produce around 1-2 millimoles of lactate per litres of blood.
What factors affect the rate of lactate accumulation?
Exercise intensity - the greater the intensity the fast OBLA occurs
Muscle fibre type - slow-twitch muscle fibres produce less lactate than fast-twitch fibres
Rate of blood lactate removal - if the rate of lactate removal is equivalent to the rate of lactate production then the concentration of blood lactate remains the same.
Respiratory exchange rate - the ratio of carbon dioxide production compared to oxygen consumption.
Fitness of performer - the fitter the performer the longer it takes for them to reach their lactate threshold.
What are factors affecting VO2 max?
Physiology
Lifestyle
Body composition
Gender
Age
Genetics
Training
How can individuals measure energy expenditure?
Indirect calorimetry
Lactate sampling
VO2 max test
Respiratory exchange ratio
What is indirect calorimetry?
This is a technique used that provides an accurate estimate of energy expenditure through gas exchange. It measures how much carbon dioxide is produced and how much oxygen is consumed at rest and during exercise.
What is lactate sampling?
This involves taking tiny blood samples and handheld device analyses the blood and indicates how much lactate is present. This is an accurate and objective measure of the level of lactate in the blood.
What is the VO2 max test?
There are multiple different VO2 max tests such as the multi-stage fitness test where the level reached on the test can be compared with a standard results table. However, the most effective test is a direct gas analysis. To carry out a direct gas analysis a performer is told to run on a treadmill with increasing intensity. The individual will run on the treadmill till exhaustion while the air they expire is calculated by a computer. the volume and concentration of oxygen in the expired air are measured and compared with the percentage of od oxygen in the atmospheric air to see how much oxygen has been used during the task.
What is the respiratory exchange ratio?
The ratio of carbon dioxide produced compared to the amount of oxygen consumed. This ratio is used to measure the intensity of exercise. It also gives information as to what fuels the performer is using during exercise.
If the ratio is close to 1 - the performer is using carbohydrates
If the ratio is approximately 0.7 - the performer is using fats
If the ratio is much greater than 1 - anaerobic respiration so more CO2 is being produced than O2 is being consumed.
What is the impact of altitude training?
Altitude training is usually done at 2500m above sea level where the partial pressure of oxygen is low. This means that there is not as much oxygen diffusing into the blood, this means that less oxygen is getting to muscles. This implies that there is a reduction in aerobic performance and VO2 max.
What are the benefits of altitude training?
It increases the red blood cell count
There is an increase in capillarization
It can also lead to an increase in lactate tolerance
What are the disadvantages of altitude training?
The benefits gained are short-lived on return to sea level.
What is the impact of HIIT training?
This can be used for both aerobic and anaerobic training. HIIT is a form of training in which periods of work are mixed with periods of recovery. It involves short intervals of maximum intensity work followed by periods of either rest or low-intensity work. the periods of high-intensity work are anaerobic and the periods of rest are aerobic.
What is the impact of plyometrics?
Plyometrics involves repeated rapid stretching and contracting of muscles to increase muscle power. This training method uses the fast-twitch fibres. The idea of this training method is that muscles can generate more force if they have previously been stretched.
What is the impact of speed, agility and quickness training (SAQ)?
This type of training focuses on improving the multi-directional movement by developing the neuromuscular system.
