Energy Systems - Applied Anatomy and Physiology (Paper 1) Flashcards
where does the energy we use for muscle contractions come from
adenosine triphosphate (ATP). the energy that is stored in ATP is released by breaking down the bonds that hold this compound together. enzymes are used to break down the bonds.
what enzyme breaks down ATP into ADP + Pi
ATPase
The conversion of fuel into energy takes place in one of three pathways which are
- aerobic system
- the ATP-PC system
- the anaerobic glycolytic system
When is the aerobic system the preferred pathway
When the exercise intensity is low and oxygen availability is high
What are the by-products of the aerobic system
- Carbon Dioxide
- water
The complete oxidation of glucose can produce how many ATPs (aerobic system)
38 ATPs (net 36)
The aerobic system has 3 stages which are
- Glycolysis
- Kreb’s Cycle
- Electron Transport Chain
What is glycolysis
- the breakdown of glucose into pyruvate
- takes place in the sarcoplasm
- net 2 ATP for every glucose molecule
What happens to the pyruvate so it can move to the next stage of the system
The pyruvic acid is oxidised into two acetyl groups and is then carried into Kreb’s cycle by coenzyme A
what is the kreb’s cycle
the two acetyl groups (formerly pyruvic acid) diffuse into the matrix of the mitochondria. and they undergo a complex cycle of reactions
describe what happens in the kreb’s cycle
- the two acetyl groups combine with oxaloacetic acid to from citric acid.
- hydrogen is removed from the citric acid and the now rearranged form of citric acid undergoes oxidative carboxylation (simply meaning carbon and hydrogen are given off)
- the carbon forms carbon dioxide which is transported to the lungs and breathed out
- the hydrogen is transported to the electron transport chain
- the result of these reactions result in the production of 2 ATP molecules
what is the electron transport chain
- the hydrogen from the krebs cycle is carried to the electron transport chain by hydrogen carriers
- occurs in the cristae of the mitochondria
- the hydrogen splits into hydrogen and electrons and they are charged with potential energy
- the hydrogen ions are oxidised to form water while the hydrogen electrons provide the energy to re-synthesise ATP
- throughout this process 34 ATP are formed
other than glucose what other fuels can the aerobic system use
- fats in the form of fatty acids and proteins in the from of amino acids
what is beta oxidation
- when stored fat is broken down into glycerol and free fatty acids
- the fatty acids then undergo a process called beta oxidation where it is converted to coenzyme a (the entry molecule for the krebs cycle)
what can produce more ATP from one molecule: fatty acids or glucose
- fatty acids
what is the predominant energy source for the aerobic system
in long duration, low intensity exercise, fatty acids are the predominant energy source however does depend on the performer
what are the advantages of the aerobic system
- more ATP can be produced (36 molecules)
- there are no fatiguing by-products
- lots of glycogen and triglyceride stores so exercise can last for a long time
what are the disadvantages of the aerobic system
- complicated system so cannot be used straight away. it takes a while for enough oxygen to become available to meet the demands of the activity and ensure glycogen and fatty acids are completely broken down
- fatty acids transportation to muscles is low and also require 15% more oxygen to be broken down than glycogen
what does it mean if something is reduced
- it means the molecules has gained hydrogen or lost oxygen
what does it mean if something is oxidised
- it means the molecule has gained oxygen or lost hydrogen
what is the fuel of the atp-pc system
phosphocreatine (PC)
what is phosphocreatine
an energy rich phosphate compound found in the sarcoplasm and can be broken down quickly and easily to release energy and re-synthesise ATP
what activities may the ATP-PC system be useful for
single maximum movements such as long lump take-off or shot putt
what is the atp-pc system
- anaerobic process
- re-sythesises ATP when the enzyme creatine kinase detects high levels of ADP
what is the equation for how PC releases energy
PC –> Pi + C + energy
this energy is then used to convert ADP to ATP in a coupled reaction
Energy –> + Pi + ADP –> ATP
For every PC how much ATP do you get
1 molecule of ATP
what are the advantages of the ATP-PC system
- ATP can be re-synthesised rapidly
- phosphocreatine stores can be-synthesised quickly
- no fatiguing by products
- possible to extend the time the atp-pc system can be utilised through use of creatine supplementation
what are the disadvantages of the atp-pc system
- there is only a limited supply of phosphocreatine in the muscle cell, only can last for 10 seconds
- one mole of ATP can be re-synthesised for every mole of PC
- PC re-synthesis can only take place in the presence of oxygen
what is the anaerobic glycolytic system
an energy system that provides energy for high-intensity exercise and for longer than the atp-pc system
what is said to be the duration of the anaerobic glycolytic system
- depends on the individuals fitness and how high the intensity of the exercise is
- e.g. a 400m athlete who has jus run the 400m wont be albe to do it again at the same pace because working flat out to exhaustion means the system will last much shorter time
- usually lasts up to 2-3 minutes
how does the anaerobic glycolytic system work
- starts with anaerobic glycolysis (where PC stroes are low and the enzyme glycogen phosphorylase breaks down the glycogen into glucose and then further broken down into pyruvic acid by phosphofructokinase where the product of this reaction is 2 ATP)
- the pyruvic acid is then further broken down into lactic acid by the enzyme lactate dehydrogenase
where does the anaerobic glycolytic system take place
sarcoplasm
what is the net result of atp produced from this system
2 molecules of ATP for 1 molecule glucose
what are the advantages of the anaerobic glycolytic system
- ATP can be re-synthesised quickly due to very few chemical reactions
- lasts longer than the ATP-PC system
- in the presence of oxygen, lactic acid can be converted back into the liver glycogen or used as a fuel through oxidation into carbon dioxide and water
- it can be used to produce an extra burst of energy
what are the disadvantages of the anaerobic glycolytic system
- lactic acid as the by-product means enzymes become denatured and prevents them from increasing the rate of reaction
- only a small amount of energy can be released from glycogen under anaerobic conditions
What is the energy continuum
A term which describes the type of respiration used by physical activities. Whether it is aerobic or anaerobic respiration depends on the intensity and duration of the exercise
State where the energy will be supplied for a performance that lasts less than 10 seconds and give an example of a sport
- ATP-PC
- 100m, long jump
State where the energy will be supplied for a performance that lasts 8-90 seconds and give an example of a sport
-ATP-PC and anaerobic glycolytic
- 200m, 400m
State where the energy will be supplied for a performance that lasts 90 seconds to 3 mins and give an example of a sport
- anaerobic glycolytic and aerobic
- 1500m, round of boxing
State where the energy will be supplied for a performance that lasts 3+ mins and give an example of a sport
- aerobic
- marathon, cross country, skiing
How is ATP generated in slow twitch fibres
- main pathway for ATP production is in the aerobic system
- produces maximum amount of ATP available from each molecule (36 ATP)
- production is slow but these fibres are more endurance based so less likely to fatigue
How do fast twitch fibres generate ATP
- main pathway for ATP is via anaerobic glycolytic energy system
- ATP production in the absence of oxygen is not efficient - only two ATP produced per glucose
- production of ATP this way is fast but cannot last long as these fibres have least resistance to muscle fatigue
What is VO2 max
The maximum volume of oxugen that can be taken up by the muscles per minute
What is oxygen consumption
The amount for oxygen we use to produce ATP
How much oxygen do we consume at rest
0.3-0.4 litres a min
What is the maximal oxygen consumption
- 3-6 litres of oxygen consumed per minute (aka our VO2 max)
- happens when exercise intensity increases and therefore the amount of oxygen consumed reaches maximal oxygen consumption
What happens when we start exercise
- insufficient oxygen is distributed to the tissues
- happens because it takes time for the circulatory system to respond to the increase in demand for oxygen and also takes time for mitochondria to adjust the rate of aerobic respiration needed
- due to this energy is provided anaerobically to satisfy the increase in demand for energy until the circulatory system and mitochondrion can cope
What is sub maximal oxygen deficit
When there is not enough oxygen available at the start if exercise to provide all the energy (ATP) anaerobically
What is EPOC
- When a performer finishes exercise, oxygen consumption still remains quite high in comparison to oxygen consumption at rest. This is because extra oxygen needs to be taken in to try and help the performer recover.
- usually characterised by breathlessness
- stands for excess post-exercise oxygen consumption
what are the two main components of EPOC
- fast component
- slow component
what is the fast component of EPOC
- uses extra oxygen that is taken in during recovery to restore ATP and PC stores
- re-staurtates myoglobin with oxygem
what are the functions of the slow component of EPOC
- removal of lactic acid
- maintenance of breathing rates and heart rates
- glycogen replenishment
- increase body temperature
how can lactic acid be removed
- 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
how can the removal of lactic acid be sped up
by performing a cool down. this is because the lactic acid can be oxidised and keeps the metabolic rate of the muscles high and keeps capillaries dilated meaning oxygen can be flushed through, removing the accumulated lactic acidho
how does the slow component of EPOC maintain breathing and heart rates
maintaining breathing and heart rates requires extra oxygen to provide the energy needed for the respiratory and heart muscles. this assists recovery as the extra oxygen is used to replenish ATP and PC stores
how does EPOC replenish glycogen stores
glycogen is the main energy provider and gets depleted due to exercise. after exercise a singificant amount of glycogen can be restored as lactic acid and converted back to blood glucose and glycogen (thru the cori cycle)
how does lactate accumulation cause muscle fatigue
- lactic acid is a by-product of glycolysis
- the higher the intensity the more lactic acid produced
- lactic acid breaks own and releases hydrogen ions
- the remaining compound (formerly lactic acid)combines with sodium ions or potassium ions to from the salt lactate
- as lactate accumulates in the muscles, more hydrogen ions are present and increases acidity
- the increase in acidity enzyme activity slows down and affects the breakdown of glycogen causing muscle fatigue
- lactate produced in the muscle diffuses into the blood and blood lactate can be measured
what is the lactate threshold
the point during exercise at which lactic acid quickly accumulates in the blood
what is OBLA
- the point when lactate levels go above 4 millimoles per litre
- stands for onset blood lactate accumulation
what are the factors affecting the rate of lactate accumulation
- exercise intensity
- muscle fibre type
- rate of blood lactate removal
- respiratory exchange ratio
- fitness of the performer
how does the intensity of exercise affect lactate accumulation
- the higher the exercise intensity the greater the demand for energy and the faster OBLA occurs.
- as fast twitch fibres are used for high intensity exercise they use glycogen as a fuel to maintain their work load
- glycogen gets broken down in the absence of oxygen into pyruvic acid and then lactic acid is formed
how does muscle fibre type affect lactate accumulation
slow twitch fibres produce less lactate than fast twitch fibres. when slow twitch fibres use glycogen as a fuel, due to the presence of oxygen, the glycogen can broken down much more effectively with little lactate production
how does the rate of blood lactate removal affect lactate accumulation
- if the rate of lactate removal is equivalent to the rate of lactate production, then the concentration of blood lactate remains the constant
- if the lactate production increases, then the lactate will start to accumulate in the blood until OBLA is reached
how does the respiratory exchange ratio affect lactate accumulation
- the respiratory exchange ratio is the carbon dioxide produced compared to the the oxygen consumed
- as the ratio has a value close to 1:0, glycogen becomes the preferred fuel and there is a greater chance of the accumulation of lactate
how does the fitness of the performer affect lactate accumulation
a person who trains regularly will be in a better to delay OBLA as adaptations occur to trained muscles. increased numbers of mitochondria and myoglobin, together with an increase in capillary density , improve the capacity for aerobic respiration and therefore avoid use of the lactate anaerobic system
what is buffering
- a process which aids the removal of lactate and maintains acidity levels in the blood and muscles
- this is how elite sprinters and power athletes cope with higher levels of lactate
- means athletes will be able to work longer before fatigue sets in
- the trained status of their working muscles will lead to adaptive responses such as more mitochondria and oxidative enzymes, capillary denisty and more myoglobin
what factors affect VO2 max/aerobic power
- physiological factors
- training
- genetics
- differences in age
- gender
- body composition
- lifestyle
how do physiological factors affect VO2 max
- increased maximum cardiac output
- increased SV/ejection fraction/cardiac hypertrophy
- increased levels of haemoglobin and red blood cell count
- increased myoglobin content
- increased capillarisation around the muscles
- increased number and size of mitochondria
- increased number and size of surface area of alveoli
- increased lactate tolerance
how does training affect VO2 max
VO2 max can be improved by up to 10-20% following a period of aerobic training
how do genetics affect VO2 max
inherited factors of physiology limit possible improvement
how does difference in age affect VO2 max
as we get older our VO2 max declines as our body systems become less efficient
how does gender affect VO2 max
men generally have approx. 20% higher VO2max than women
how does body composition affect VO2 max
a higher percentage of body fat decreases VO2 max
how does lifestyle affect VO2 max
smoking, sedentary lifestyle, poor diet and poor fitness can all reduce VO2 max values
why do you measure energy expenditure
- gives an indication of the intensity of the exercise
- identify level of fitness
- highlight dietary requirements
- provide feedback on the effectiveness of training
what are the methods to investigate energy expenditure
- indirect calorimetry
- lactate sampling
- VO2 max test
- respiratory exchange ratio (RER)
what is indirect calorimetry
- a technique that provides an accurate estimate of energy expenditure through gas exchange
- it measures how much CO2 produced and how much oxygen is consumed at rest and exercise
- calculating the gas volumes enables us to find out the main substrate being used (fat or carbohydrate)
How is the indirect calorimeter test good
It is accurate, very reliable and it gives a precise calculation of VO2 and VO2 max
What sporting examples/athletes would use the indirect calorimetry test
Marathon/long distance running
What is lactate sampling
- involves taking a blood sample and a hand held device to analyse the blood and indicates how much lactate is present
- accurate and objective measure of the level of lactate in the blood
How is lactate sampling used
- to test how much lactate is in the blood
- means of measuring exercise intensity (the higher the exercise intensity at which the lactate threshold occurs, the fitter the athlete is considered to be)
- can give an idea of fitness (allows the performer to select relevant training zones in order to achieve desired effects)
- used for comparison to see if improvement has occurred (if results shows a lower lactate level at the same intensity of exercise then it indicates that the performer has increased their speed/power -> increased time to exhaustion -> improved recovery HR and therefore higher lactate threshold)
what is the VO2 max test
- a test such as the 12 min cooper run, bleep test etc. and then results get compared to a standard results table. sports science labs produce more reliable results using direct gas analysis
what is direct gas analysis
method of testing for VO2 max involving increasing intensities on a treadmill/cycle ergometer.
what is respiratory exchange ratio
the ratio to which carbon dioxide produced compared to oxygen consumed and is used as a measure of exercise intensity. provides information about the fuel usage during exercise (fats, proteins, carbs).
how do you calculate RER
CO2 expired per min
RER = ————————————————————-
O2 consumed per min
what do the RER values tell us
- RER close to 1 = main fuel is carbohydrates
- RER value approx. 0.7 = performer using fats
- RER greater than 1 = anaerboci respiration so more CO2 being produced than O2 consumed
What is the impact of high altitude on the body in terms of the respiratory system
- at high altitude partial pressure of O2 drops
- this causes a reduction in the diffusion gradient of oxygen between the air and lungs and the alveoli and blood
- this means not as much oxygen diffuses into the blood so the Haemoglobin isn’t fully saturated with oxygen and the O2 carrying capacity of the blood is lowered
- as less O2 is delivered to working muscles there is a reduction in aerobic performance and VO2 max and a quicker onset of anaerobic respiration
What is altitude training
Training done usually at 2500m+ above sea level where the partial pressure of O2 is lower. It is done to acclimatise athletes to lower levels of oxygen availability
What are the advantages of altitude training
- increased number of EPO leading to increased number of RBCs
- increased blood viscosity (enhances oxygen transport and delivery to the tissues)
- increased capillarisation
- enhanced oxygen transport
What are the disadvantages of
- difficult to train at the same intensities due to reduction of partial pressure of oxyegn
- altitude sickness
- psychological problems like homesickness
- expensive
- benefits can be lost upon return to sea level
- increased lactate production (lack of oxygen means more anaerobic respiration)
What is HIIT
Interval traning. Can be used for both anaerobic and aerobic respiration. Works by a period of work followed by a period of rest
How is made to be HIIT training specific
- the duration of the work interval
- the intensity or speed of the work interval
- duration of recovery interval
- number of work intervals and recovery intervals
What is the positives of HIIT training
Improves fat burning potential, glucose metabolism no both anaerobic and aerobic endurance
What is plyometrics
Involves rapid stretching and contracting of muscles to increase muscle power
What are the three phases of plyometrics
- eccentric phase
- amortisation phase
- concentric phase
What is the eccentric phase
On landing, the muscle performs an eccentric contraction where it lengthens under tension
What is the amortisation phase
The time between eccentric and concentric muscle contractions. This needs to be shorts as possible so the energy stored from the eccentric contraction is not lost. When an eccentric contraction occurs, a lot of energy required to stretch or lengthen the muscle is lost as heat but some of the energy can be stored and available for the subsequent concentric contraction
What is the concentric phase
This stage uses the stored energy to increase the force of contraction
What is SAQ
A type of training aiming to improve multi-directional movement through developing the neuromuscular system. As SAQ uses activities performed with maximum force at high speed, energy is provided anaerobically
