Energy systems Flashcards
what are the three energy systems?
–ATP-PC system
–Anaerobic glycolytic system
–Aerobic system
what does the energy system used depend on?
–intensity of exercise
–duration of exercise
–presence of O2
what does ATP stand for?
adenosine triphosphate
what is ATP used for?
energy for muscular contractions
what is the formula for ATP break down?
ATP–> ADP + Pi
what are features of the ATP-PC system?
– uses phosphocreatine as a fuel
–initially uses stored ATP
–lasts 5-8 seconds
–takes place without O2// so anaerobic process
–its a coupled reaction
–for every molecule of PC broken down, one ATP molecule is released
what are the reactions involved in the ATP-PC system?
PC–>Pi + C + energy
energy + Pi + ADP –> ATP
what are the benefits of using the ATP-PC system?
– ATP can be re-synthesised quickly
– PC stores can be restored quickly
– no fatiguing by-products produced
–creatine supplementation can extend the time that ATP-PC system is used for
–PC stores broken down quickly and easily to release energy for short bursts of exercise
– rapid availability makes it good for a deadlift, javelin, 100m…
what are the drawbacks of using the ATP-PC system?
– there is a limited supply of phosphocreatine in the muscles – so only lasts 10 seconds max
– only one molecule of ATP can be re-synthesised per molecule of PC
–PC restoration can only take place in the presence of O2 when the intensity of exercise has decreased
what are features of the anaerobic glycolytic system?
–it involves glycolysis== glycogen->glucose->pyruvic acid->lactic acid
–LA produced when there is no O2 present
–provides energy for high intensity exercise, longer than the ATP-PC system
–can peak at 45 seconds and last for up to 3 minutes
–releases 2 ATP molecules
what are the benefits of the anaerobic glycolytic system?
–ATP can re-synthesised quickly due to very few chemical reactions
– lasts longer the the ATP-PC system
–when O2 is available LA can be converted back into liver glycogen or used as fuel for oxidation of CO2+H20
–can be used in a sprint finish
what are the drawbacks of the anaerobic glycolytic system?
–LA is a harmful/fatiguing by-product
–only a small amount of energy can be released from glycogen under anaerobic conditions
what are the features of the aerobic system?
– includes three stages: glycolysis, krebs cycle and electron transport chain
– it produces 32-34 ATP molecules
– it takes place in the presence of O2
–beta oxidation occurs when proteins and fats are added
–used at low intensity exercise
what is the process in glycolysis during the aerobic system?
glycogen-> glucose-> pyruvic acid-> acetyl coenzyme A
– releases 2 ATP molecules
what is the process or the Kreb’s cycle?
acetyl coenzyme A + oxalocetic acid = citric acid + CO2 + H+ + 2XATP
what occurs during beta oxidation?
when proteins and fats are added to the Kreb’s cycle
– fatty acids are converted into acetyl coenzyme A
– one molecule of fatty acids produces more ATP than one molecule of glucose
– low intensity so fatty acids are main energy source
what is involved in the electron transport chain?
in the presence of O2, H2O is produced and 32-34 ATP molecules released
what is the energy continuum of physical activity?
it describes which energy system is used for different types of activity
– the three energy systems don’t act independently– they all contribute during exercise but one will be more dominant provider
how are slow twitch muscle fibres and energy systems related?
– ATP is produced in aerobic system
– ATP production is slower
–more endurance based sl less likely to fatigue
– produces the max amount of ATP
how are fast twitch muscles fibres and energy systems related?
ATP produced in anaerobic glycolytic system
– only 2 ATP produced per glucose molecule
–ATP production fast
–ATP doesn’t last for long as they are less resistant to fatigue
what is oxygen consumption?
the amount of O2 we use to produce ATP (usually referred to as VO2)
what is EPOC?
the amount of O2 consumed during recovery above that which would not have been consumed at rest during the same time
what is sub-maximal oxygen deficit?
when there is not enough O2 available at the start of exercise to provide all the energy aerobically
– this is due to mitochondria and circulatory system not being ready to produce sufficient O2
what is the fast component in recovery?
alactacid/alactic debt. component
–restores ATP + PC stores
– resaturates myoglobin with O2
– uses 2-4 litres of O2
–replenishes 50% in 30 secs, 75% in 60 secs, 100% up to 3 mins
what is the slow component in recovery?
lactacid component
–takes up to an hour or longer depending on intensity of exercise
–includes: lactic acid removal, maintaining high breathing + HR, increases body temp + glycogen replenishment
explain how lactic acid is removed by the body?
– O2 needs to be present
– so LA can be converted back into pyruvate + oxidised into CO2 + H2O,, water in inactive muscles and organs
–also transported to liver where its converted into glucose + glycogen in the Cori cycle
-converted into protein
-removed in sweat and urine
what can accelerate the removal of LA?
– a cool down
– as it oxidises it
–due to high metabolic rate and capillaries kept dilated
why is a higher breathing + HR maintained?
– to bring in more O2 for energy needed for the respiratory and heart muscles
–more O2 for replenishing ATP + PC stores, re-saturating myoglobin + removing lactic acid
why is increased body temperature maintained?
– enables respiratory rates to remain high
– helps to take in more O2
explain how and why glycogen is replenished?
–glycogen stores depleted during exercise
–depends on: type of exercise + when and how much carbs are consumed following exercise
– restored when LA converted into blood glucose and glycogen
how long can glycogen replenishment take?
–several days= after marathon
–less than an hour= after 100m sprint
how can glycogen replenishment be accelerated?
– eating a high protein and carb diet
– eating within an hour after exercise
what are the two nutritional windows for optimal recovery?
1)–first 30 minutes after exercise– carbs+proteins eaten in 3:1/4:1 to help with muscle glycogen replenishment
2)–1-3hrs after exercise– meal high in protein, carbs+ healthy fats
explain how lactate accumulation occurs and its effects?
– LA produced in anaerobic glycolytic system
– the higher the intensity, the more LA produced
–accumulation of this increases acidity which slows down enzyme activity, affecting breakdown of glycogen == muscle fatigue
what is the lactate threshold/OBLA?
the point during exercise at which LA quickly accumulates in the blood
- starts at 4mmol/litre
what does OBLA stand for?
Onset
Blood
Lactate
Accumulation
what factors affect lactate accumulation?
– intensity– higher=faster accum
–fitness level– more mitochondria, improved gas exchange + higher fitness =slower accum
–VO2 max– higher= slower accum
–muscle fibre type– slow twitch=slower accum
–respiratory exchange ratio(RER)– closer to 1=faster accum
what is RER (respiratory exchange ratio)?
–the ratio of CO2 produced to O2 used
-a method for measuring energy expenditure of an athlete
-estimates use of fats+ carbs used during exercise
-tells if performer working anaerobically, aerobically and which energy system
what is lactate sampling?
taking blood samples to measure lactic acid levels
-ensures training is at correct intensity
-provides accurate measure
-measures OBLA
what do different RER values mean?
close to 1= carbs used
approx. 0.7= fats used
greater than 1= anaerobic respiration so more CO2 produced: O2 used
what is indirect calorimetry?
measures the production of CO2 and consumption of O2
what is VO2 max?
maximum vol. of O2 that can be utilised by the working muscles per minute
what are the VO2 max tests?
–multi-stage fitness test
–harvard step test
–cooper run
–direct gas analysis in a sports science lab = most accurate
what is A-VO2 difference?
the difference between partial pressure of O2 in arterial + venous blood // how much O2 is used by the muscles
what happens to A-VO2 diff during exercise?
increases – as more O2 extracted by muscles for energy production(systems)
what is lactate accumulation a percentage of?
VO2 max
what does a higher VO2 max cause?
-delay in LA accum./OBLA
-higher lactate threshold
-greater endurance capacity
-LA broken down quickly
what factors contribute to a performers VO2 max?
–age – decreases with age
–gender– men have 20% higher than women
–genetics
–training
– lifestyle– lack of exercise, smoking + poor diet
–body composition– higher % of body fat decreases VO2 max
–physiology– number of slow twitch fibres/capillary density/ no. mitochondria/ Hb content/ SA of alveoli/ RBC count/ efficiency of heart
