Energy systems Flashcards
ATP adenosine triphosphate
energy we use for muscle contractions
ATPase
enzyme used to break down ATP leaving adenosine di-phosphate (ADP) and inorganic phosphate (Pi)
conversion of ADP and Pi back to ATP takes place through:
the aerobic system
the ATP-PC system
the anaerobic glycolytic system
the aerobic system
low intensity- high oxygen supply-long duration e.g. jogging
breaks down glucose into CO2 and O2
produces up to 38 molecules of ATP
fats and proteins can be broken down (fatty acids and amino acids)
the aerobic system -Glycolysis
the first stage is anaerobic
the breakdown of glucose to pyruvic acid
for every molecule of glucose undergoing glycolysis, 2 molecules of ATP are produced
the aerobic system- Krebs cycle
acetyl groups combine with oxaloacetic acid to form citric acid. hydrogen is removed
carbon forms CO2 and is breathed out by the lungs
hydrogen is taken to the ETC
produces 2 molecules of ATP
the aerobic system- Electron transport chain
hydrogen splits into hydrogen ions and electrons which are charged with potential energy
hydrogen ions are oxidised to form water
hydrogen electrons provide energy to resynthesise ATP
34 ATP produced
Beta oxidation
fatty acids undergo beta oxidation where they are converted into acetyl coenzyme. (entry for krebs cycle)
advantages of the aerobic system
more ATP produced (36)
no fatiguing by products (only co2 and h2o)
lots of glycogen and triglyceride stores so exercise can last longer
disadvantages of the aerobic system
takes a while for enough oxygen to be available for system to work
fatty acid transportation to muscles is low and requires 15% more O2 to be broken down than glycogen
the ATP-PC system
uses phosphocreatine (PC) as its fuel. it can be broken down quickly and is easy to release energy to resynthesise ATP
rapidly available
important for single maximal movements (long jump, shot put)
5-8 seconds
can only replenish when oxygen is available at low intensity
how ATP-PC works to provide energy
anaerobic process
resynthesises ATP when there are high levels of ADP
breaks down phosphocreatine in muscles to release energy
energy+Pi+ADP=ATP
delays onset of anaerobic glycolytic system
advantages of ATP-PC system
ATP can resynthesise rapidly
phosphocreatine stores can be resynthesised quickly (only takes 3 mins)
no fatiguing by products
it is possible to extend duration through creatine supplimentation
disadvantages of ATP-PC system
only a limited supple of phosphocreatine in the muscles (so only lasts up to 8s)
only one mole of ATP can be resynthesised for every mole of PC
PC resynthesis can only take place in the presence of oxygen
the anaerobic glycolytic system
high intensity, longer duration (than ATP-PC) 2-3 mins if not full intensity
e.g. 400 m runner
resynthesises ATP from the breakdown of the fuel glucose
how Anaerobic glycolytic system works to provide energy
when PC stores are low, glycogen is broken down into glucose and then into pyruvic acid (this is anaerobic glycolysis)
pyruvic acid is then broken down again into lactic acid by LDH
energy is released to allow ATP to resynthesise
2 molecules of ATP produces for 1 molecule of glucose (actually 4 molecules released but 2 are used for glycolysis)
advantages of Anaerobic glycolytic system
ATP can be resynthesised quite quickly due to very few chemical reactions and lasts longer than ATP-PC system
in the presence of O2, lactic acid can be converted back into liver glycogen or used as fuel through oxidation into carbon dioxide and water
can be used for a sprint finish
disadvantages of anaerobic glycolytic system
lactic acid is the final by-product
only a small amount of energy can be released from glycogen under anaerobic conditions
energy continuum
describes which energy system is used for different types of physical activity
intensity and duration decide which energy system is used
what energy system does
100m sprinter
marathon runner
ATP-PC
aerobic energy system
energy continuum thresholds
ATP-PC system is exhausted-> anaerobic glycolytic is exhausted-> aerobic
slow twitch muscle fibres
low to medium intensity
aerobic respiration is main source of receiving fuel
fast twitch
high intensity activity
anaerobic respiration (produces only 2 atp. muscles fatigue quicker)
e.g. sprinting
slow twitch (Type II)
the main pathway for ATP production in the aerobic system
produces the maximal amount of ATP available from each gluecose molecule (up to 36 ATP)
production of ATP is slow but these fibres are more endurance based so less likely to fatigue
fast twitch (Type IIx)
the main pathway for ATP production is via the lactate anaerobic energy system
ATP production in the absence of oxygen is not efficient
production of ATP this way is fast but cannot last for long as these fibres have least resistance to muscle fatigue
oxygen consumption
amount of oxygen we use to produce ATP.
usually referred to as VO2
at the start of exercise, oxygen consumption increases to provide more ATP.
as intensity increases, so does the amount of oxygen consumed until a performer reaches maximal oxygen consumption (this is VO2 max)
VO2 max
the maximum volume of oxygen that can be taken up by the muscles per minute
determines endurance
largely genetically determined
physiological factors affecting VO2 max
increased:
maximum cardiac output
stroke volume/ejection fraction
heart rate range
oxygen to muscles
red blood cells and haemoglobin
glycogen stores
myoglobin content
capillarisation around muscles
number and size of mitochondria
surface area of alveoli
lactate tolerance
other factors affecting VO2 max
lifestyle- smoking, poor fitness
body composition- more body fat reduces VO2 max
training-aerobic training improves VO2 max by 10-20%
genetics
gender- men have about 20% higher VO2 max
differences in age- VO2 max declines with age
sub maximal oxygen deficit
when there is not enough oxygen available at the start of exercise to provide all the energy (ATP) aerobically
EPOC
the amount of oxygen consumed during recovery above that which would have been consumed at rest during the same time
the fast component EPOC (alactacid component)
uses extra O2 taken in during recovery to restore ATP + phosphocreatine + re-saturate myoglobin with oxygen
myoglobin
high affinity for oxygen
oxygen stores are limited after exercise
replenished trough EPOC
the slow component EPOC (lactacid component)
removal of lactic acid
maintenance of breathing and heart rates
glycogen replenishment
increase in body temperature
the slow component EPOC (lactacid component)
removal of lactic acid
-o2 converting it back into pyruvate and ocidised into carbon dioxide and water to be used as energy
-the cori cycle
-converted into protein
-removed in sweat and urine
the cori cycle
lactic acid is transported to the liver where it is converted to blood gluecose and glycogen
maintenance of breathing and heart rates
extra oxygen from increased breathing and HR is used to replenish ATP and phosphocreatine stores and re-saturate myoglobin and remove lactic acid (returning body to pre-exercise state)
glycogen replenishment
glycogen is main energy provider
replenishment depends on the type of exercise undertaken + how much carbohydrates are consumed
increase in body temperature
when temp is high, respiratory rates are also high
this helps performer take in more oxygen
lactate accumulation
lactate is made from broken down lactic acid
accumulates in the muscles and combines with hydrogen ions to increase acidity
slows enzyme activity and affects breakdown of glycogen- causing muscle fatigue
lactate produced in the muscles diffuses into the blood and blood lactate can be measured
lactate threshold
switching from aerobic to anaerobic
lactic acid quickly accumulates in the blood
expressed as a % of VO2 max
as fitness increases, lactate threshold becomes dalayed
exercise at just below our lactate threshold
OBLA
when lactate level go above 4 mmol per litre
body is unable to produce enough oxygen to break down lactate so levels of lactate accumulate
gives indication of endurance capacity
Multi stage fitness test and OBLA example
as the test becomes more demanding because of reduced time to complete each shuttle, the performer eventually reaches a point where energy cannot be provided aerobically. this means the performer has to use the anaerobic systems to re-synthesise ATP. levels of lactate produced in the muscles increase until muscle fatigue occurs and the performer slows down or is no longer able to keep up with the beep.
factors affecting the rate of lactate accumulation:
exercise intensity
the higher the intensity, the greater the demand for energy (ATP) and the faster OBLA occurs.
fast twitch muscle fibres used for high intensity
need glycogen as fuel.
when glycogen is broken down in the absence of oxygen, lactic acid is formed
factors affecting the rate of lactate accumulation:
muscle fibre type
slow twitch fibres produce less lactate than fast twitch fibres. when slow twitch fibres use glycogen as a fuel, it can be broken down more effectively and with little lactate production.
factors affecting the rate of lactate accumulation:
rate of blood lactate removal
if rate of removal is the same as production, blood lactate remains constant.
if production increases, it will accumulate until OBLA occurs
factors affecting the rate of lactate accumulation:
the respiratory exchange ratio
ratio of CO2 produced compares to O2 consumed
factors affecting the rate of lactate accumulation:
fitness of the performer
a fitter person will be able to delay OBLA due to increased mitochondria and myoglobin and capillary density, improve the capacity for aerobic respiration and therefore avoid using anaerobic glycolytic system
lactate producing capacity
elite sprinters and power athletes have better anaerobic endurance than non-elite sprinters
they have adapted to cope with high levels of lactate
buffering has increased the rate of removal therefore reducing lactate levels
buffering
athletes can work at higher intensity for longer before fatigue sets in.
can tolerate higher levels of lactate
greater number of mitochondria, myoglobin and capillary density
measurements of energy expenditure:
indirect calorimetry
provides and accurate measurement of energy expenditure through gas exchange.
measures how much CO2 is produced and how much O2 is consumed at rest and aerobic exercise.
gives precise calculation of VO2 and VO2 max
measurements of energy expenditure:
lactate sampling
small blood sample indicating how much lactate is present
gives idea of level of fitness
allows performer to select relevant training zones
can show lactate comparison if done regularly
measurements of energy expenditure:
VO2 max test
direct gas analysis- measures the concentration of oxygen that is inspired and the concentration of carbon dioxide expired
multi-stage fitness test can also be used
measurements of energy expenditure:
respiratory exchange ratio (RER)
ratio of co2 produced compared to the o2 consumed
provides info on fuel usage during exercise
rer= vco2/vo2
impact of specialist training methods on energy systems:
altitude training
2500m+
lower partial pressure of oxygen
reduction in diffusion gradient
haemoglobin is not fully saturated with blood so there is a lower o2 carrying capacity.
reduces vo2 max and aerobic performance
benefits of altitude training
increase RBC count
increase concentration of haemoglobin
increase in capillarisation and EPO
enhanced oxygen transport
increase lactate tolerance
negatives of altitude training
difficult to train at same intensity due to partial pressure of o2
loss of fitness/ detraining
altitude sickness has effect on training programme
homesickness
only lasts for 14 days.
impact of specialist training methods on energy systems:
high intensity interval training (HIIT)
used for aerobic and anaerobic
periods of maximal intensity work with periods of low to moderate recovery
duration of work and recovery
intensity of work and recovery
improves fat burning potential, glucose metabolism, aerobic and anaerobic performance
impact of specialist training methods on energy systems:
plyometrics
repeated rapid stretching and contracting of muscles to increase muscle power
high intensity explosive activities - hopping
uses fast twitch muscle fibres
eccentric phase-muscle lengthens under pressure
amortisation phase- time between eccentric and concentric muscle factors
concentric - uses stored energy to increase force of contraction
impact of specialist training methods on energy systems:
speed. agility, quickness SAQ
improves multi directional movement through developing the neuromuscular system
zig zag runs
foot ladders
maximal force at high speed
anaerobic energy
