Energy Systems Flashcards
What is the only useable form of chemical energy in the body ?
ATP = adenosine triphosphate
ATP = 1 x molecule of adenosine & 3 x molecules of phosphate
The energy we get from foods is broken down to release the energy that is used to form ATP
How is ADP formed ?
ATPase is used to break down ATP, leaving ADP + Pi, releasing energy as it does.
What are the 3 energy systems ?
Aerobic
ATP-PC
Anaerobic glycolytic
What is the aerobic system ?
Glucose + oxygen > energy + carbon dioxide + water
Complete oxidation of glucose can produce 38 molecules of ATP
Fat and protein can also be broken down
Products of fat and protein are reduced to the molecule acetyl coenzyme A
What are the 3 stages of the aerobic system ?
Glycolysis (or Beta Oxidation)
Krebs Cycle
Electron Transport Chain
Explain the 1st stage of the aerobic system
This anaerobic stage takes place in the sarcoplasm of the muscle cell
Each molecule of glucose generates 2 molecules of ATP
Before the pyruvic acid can enter Krebs cycle it is oxidised into two acetyl groups by coenzyme A
What enzyme breaks down glycogen into glucose ?
Phosphofructokinase
Explain the 2nd stage of the aerobic system
The two acetyl groups diffuse into the matrix of the mitochondria
The acetyl groups combine with oxaloacetic acid forming citric acid
Hydrogen is removed and citric acid undergoes oxidative carboxylation (carbon and hydrogen are given off)
Carbon forms carbon dioxide
2 ATP molecules are produced from the Krebs cycle
Explain the 3rd stage of the aerobic system
Hydrogen is carried to the electron transport chain
Occurs in the cristae of the mitochondria
Hydrogen splits into hydrogen ions and electrons
Hydrogen ions are oxidised to form water
Hydrogen electrons provide energy to re-synthesise ATP
34 ATP molecules are produced
What is beta oxidation in the aerobic system ?
Stored fat broken down into glycerol and free fatty acids for transportation by the blood
Beta oxidation causes these fatty acids to be converted into acetyl coenzyme A
Fat metabolism then follows the same path as glycogen metabolism
More ATP can be produced from one fat molecule
Advantages and disadvantages of the aerobic system
Advantages:
More ATP is produced (38)
No fatiguing by-products
Plenty fuel stores
Disadvantages:
Takes a while before enough oxygen is available for the process
Fatty acid transportation to muscles is low
What is the ATP-PC system ?
Uses Phosphocreatine as its fuel
PC is an energy-rich compound found in the sarcoplasm of the muscle
Can be broken down quickly and easily to release energy
Rapid availability is for single maximal movements
Only enough PC to last for 5-8 seconds
Can only be replenished during low intensity work
How does the ATP-PC system work ?
Anaerobic process
Resynthesises ATP when the enzyme creatine kinase detects high levels of ADP
It breaks down the phosphocreatine in the muscles to phosphate and
creatine, releasing energy
Energy is then used to convert ADP to ATP in a coupled reaction
Advantages and disadvantages of the ATP-PC system
Advantages:
ATP Can be re-synthesised rapidly
Phosphocreatine stores can be re-synthesised quickly
There are no fatiguing by-products
Can extend the time the ATP-PC system through use of creatine supplementation
Disadvantages:
There is only a limited supply of phosphocreatine in the muscles
Only one molecule of ATP can be re-synthesised for every molecule of PC
PC re-synthesis can only take place in the presence of oxygen
What is the Anaerobic glycolytic system ?
This system provides energy for high intensity activity for longer
How long this system lasts depends on the fitness of the individual
Lasts about 45 seconds - 3 minutes
How does the Anaerobic glycolytic system work ?
Glucose is stored in the muscles and liver as glycogen
When PC stores are low, the enzyme glycogen phosphorylase is activated to break down the glycogen into glucose
Glucose is then further broken down in pyruvic acid by the enzyme phosphofructokinase
Takes place in the sarcoplasm of the muscle
The pyruvic acid is then further broken down into lactic acid by the enzyme lactate dehydrogenase
The net result is 2 molecules of ATP
Advantages and disadvantages of the Anaerobic glycolytic system
Advantages:
ATP can be re-synthesised quite quickly
In the presence of o2, lactic acid can be converted into liver glycogen
It can be used for a sprint finish
Disadvantages:
Lactic acid acts as the by-product
Accumulation of acid in the body de-natures enzymes
Only a small amount of energy can be released from glycogen
What is the energy continuum ?
The Energy continuum describes which energy system is used for different types of exercise
Depends on the duration and intensity
How do muscle fibres and energy systems work together ?
Slow twitch:
Main pathway for ATP production is in the aerobic system
Produces up to 38 ATP from each glucose molecule
Production of ATP is slow but these fibres are more endurance based
Fast twitch:
Main pathway for ATP is the lactate anaerobic energy system
ATP production in the absence of oxygen is not efficient (2 ATP)
Production of ATP this way is fast but cannot last for long
Which energy system is used during low intensity exercise ?
Aerobic
What is VO2 Max and what is it measured in ?
Maximum volume of oxygen that can be taken up and used by the muscles per minute
(ml/kg/min)
Explain Sub-maximal oxygen deficit
When we start to exercise insufficient oxygen is distributed to the tissues.
Takes time for circulatory system to respond to the increase in
demand for oxygen.
Energy is provided anaerobically to satisfy the increase in demand for energy until the circulatory system and mitochondria can cope.
Explain Maximal accumulated oxygen deficit
Gives an indication for anaerobic capacity.
Oxygen deficit is bigger during maximal exercise as the performer is short of more oxygen at the start
What is Excess Post-exercise oxygen consumption (EPOC) ?
The amount of oxygen consumed during recovery above that which would have been consumed at rest during the same time.
The fast component (alactacid component)
The slow component (lactacid component)
Explain the fast component of EPOC
Myoglobin has a high affinity for oxygen
It stores O2 in the sarcoplasm
After exercise, oxygen stores in the myoglobin are limited
Surplus of oxygen supplied via EPOC helps replenish these stores
Explain the slow component of EPOC
Lactic acid accumulates during exercise
Lactic Acid can be converted back into pyruvate and oxidised into CO2 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
Maintaining breathing and heart rates
When temperature remains high, respiratory rates also remain high
Glycogen is the main energy provider
Replacement of glycogen depends on the type of exercise completed
Eating high carb meal will accelerate glycogen replenishment
What energy system is used during high intensity and short duration exercise ?
ATP-PC
Anaerobic glycolytic system
What is lactate accumulation ?
Lactic acid produced as a by-product
Lactic acid is quickly broken down releasing hydrogen ions
Remaining compound then combines with sodium or potassium ions to form the salt lactate
As lactate accumulates more hydrogen ions are present
Increased acidity slows down enzyme activity
Lactate produced in muscle diffuses into the blood
What is Lactate Threshold ?
Crossing of aerobic/anaerobic threshold
The point at which lactic acid quickly accumulates in the blood
(increase of 2 mmol per litre of blood above resting levels)
Expressed as a percentage of VO2 max
Average performers = 50-60% VO2 max
Elite performers = 70-90% VO2 max.
Training delays lactate threshold
What is OBLA ?
Onset Blood Lactate Accumulation
(increase of 4 mmol per litre of blood above resting levels)
Gives an indication of endurance capacity
Factors affecting lactate accumulation
Exercise Intensity
Muscle fibre type
Rate of blood lactate removal
The respiratory exchange ratio
Fitness of the performer
What is buffering ?
Exercise Intensity
Muscle fibre type
Rate of blood lactate removal
The respiratory exchange ratio
Fitness of the performer
Factors affecting VO2 max
Physiological
Lifestyle
Body composition
Gender
Age
Genetics
Training
Explain the physiological factor of VO2 max
Increased maximum cardiac output
Increased stroke volume/ejection fraction/cardiac hypertrophy
Greater heart rate range
Less O2 being used for heart muscle so more available to muscles
Increased levels of haemoglobin and RBC count
Increased stores of glycogen and triglycerides
Increased myoglobin content
Increased capillarisation around muscles
Increased number and size of mitochondria
Increased surface areas of alveoli
Increased lactate tolerance
Explain the lifestyle factor of VO2 max
Smoking, sedentary lifestyle, poor diet and poor fitness reduce VO2 max levels
Explain the body composition factor of VO2 max
A higher percentage of fat decreases VO2 max
Explain the gender factor of VO2 max
Men generally have approx 20% higher VO2 max than women
Explain the age factor of VO2 max
As we get older our VO2 max declines as our body systems become less efficient
Explain the genetics factor of VO2 max
Inherited factors of physiology limit possible improvement
Explain the training factor of VO2 max
VO2 max can be improved by 10-20% following a period of aerobic training (continuous, fartlek and aerobic interval)
Explain indirect calorimetry
Measures the production of CO2 and/or the consumption of O2
Calculating gas volumes also enables us to find out the main substrate being used
Explain lactate sampling
Involves taking a tiny blood sample and a handheld device analyses how much lactate is present
It is an accurate objective measure of blood lactate levels
Can also be used as a means to measure exercise intensity
Explain Direct gas analysis
Measures the concentration of O2 that is inspired and the concentration of CO2 that is expired
Run, cycle or row to exhaustion in lab conditions
Explain Respiratory exchange ratio
Ratio of carbon dioxide produced compared to oxygen consumed
Used as a measure of exercise intensity
Provides info about fuel usage during exercise
RER = Carbon dioxide expired per min (VCO2) / Oxygen consumed per min (VO2)
What are the RER values ?
1 = performer using carbohydrates
0.7 = performer using fats
>1 = anaerobic
What is altitude training ?
Training that takes place at 2500m above sea level
Partial pressure of oxygen drops as altitude increases
Reduces the diffusion gradient
Less O2 carrying capacity
Disadvantages and Advantages of altitude training
Advantages:
Improves aerobic performance
Increase the number of red blood
Increase in EPO
When return to sea level more RBC means more o2 available
More o2 = more ATP production.
Disadvantages:
Reduction in aerobic performance
Very difficult to train
Can result in loss of fitness or detraining
Altitude sickness can occur
What is HIIT ?
Aerobic and anaerobic training
Short intervals of maximum intensity
Variables ensuring HIIT training is specific
Duration of work interval
Intensity or speed of work interval
Duration of recovery interval
Number of work and recovery intervals
What is plyometric training ?
Strength training that improves speed and power
It involves high intensity explosive actions
Based on principle that muscles can generate more force if they have been previously stretched
