What is ATP?
- adenosine triphosphate
- usable form of energy in the body
- consists of adenosine and 3 phosphate groups
- broken down by ATPase
- releases energy so its an exothermic reaction
- energy from foods is converted into ATP
What are the 3 energy systems that resynthesise ATP?
- ATP-PC system
- lactate anaerobic system
- aerobic system
What does the chosing of the energy system used to resynthesise ATP depend on?
- duration of exercise
- intensity of exercise
- oxygen availibility
How long does it take for ATP stores in the muscles to be used up?
2-3 seconds
How does the ATP-PC system work?
- phosphocreatin (PC) is found in the sarcoplasm of the muscle
- creatine kinase breaks the bond in PC which releases energy
- ADP molecule uses the energy and the Pi group to create ATP in a coupled reaction
- 1 molecule of PC creates 1 molecule of ATP
- anaerobic
- lasts 10 seconds
What are the positive and negatives of the ATP-PC system?
+ ATP can regenerate quickly
+ PC stores are replenished in 3 min
+ no fatiguing by-products
+ system can be extended by the use of creatine supplements
- only lasts 10 sec
- limited supply of PC in the body
- I ATP per PC
- regeneration only takes place with oxygen
How does the lactate anaerobic energy system work?
Anaerobic glycolytic system
- provides energy for high intensity exercise
- Glycogen is broken down into glucose by phosphofructokinase (glycolysis)
- this releases 2 ATP and energy
- glucose is broken down into pyruvic acid by glycogen phosphorylase
- pyruvic acid is broken down into lactic acid by lactate dehydrogenase
- anaerobic
- produces 2 ATP total
- lasts 40 seconds
What are the advantages and disadvantages of the lactate anaerobic system?
+ ATP is regenerated quickly
+ lactic acid is converted to glycogen when O2 is present
+ produces and extra burst of energy
- lactic acid by-product
- only small amount of energy is released
What are the differences between ATP generation in fast and slow twitch muscle fibres?
Fast-twitch they are recruited for high intensity activities so anaerobic respiration is their main pathway for energy production
Slow-twitch they are recruited for low to medium intensity exercise so therefore use aerobic respiration for energy production
What is lactate accumulation?
- when during higher intensity exercise more lactic acid is produced
- this releases H+ ions
- as lactate accumulates it releases more H+ ions
- these increase the acidity of the blood
- slows down enzyme activity
- causes muscle fatigue
What is the lactate threshold?
The point at which lactic acid accumulates rapidly in the blood
What is the onset of blood lactate accumulation?
(OBLA)
- the crossing of the lactate threshold is the point at which lactic acid accumulates rapidly in the blood
- at high intensities of exercise the body is unable to produce enough O2 to break down the lactate
- the lactate levels build up and accumulate past 4millimoles/ litre
- this is known as OBLA
What are the factores affecting the rate of lactate accumulation?
- exercise intensity
- muscle fibre type
- VO2 max
- respiratory exchange ratio
- fitness level
What is buffering?
A process that aids the removal of lactate and maintains acidity levels in the blood and muscles
Hoe does the aerobic energy system work?
- consist of three stges:
- glycolysis
- krebs cycle
- electron transport chain
- low intensity exercise
- high oxygen supply
- produces large amounts of ATP
What happens during glycolysis?
- glucose is broken down into pyruvic acid
- produces 2 ATP
- happens in the sarcoplasm
(converted into acetyle coenzyme A)
What happens during the Kreb’s cycle?
- acetyle coenzyme a combines with oxaloacetate to form citric acid
- undergoes oxidative carboxylation to give off carbon dioxide and hydrogen
- produces 2 molecules of ATP
- happens in the mitochondrial matrix
- uses oxygen
What happens during beta oxidation?
- fats enter the krebs cycle and by being broken down into glycerol and three fatty acids
- fatty acids are converted into acetyl coenzyme A so it can enter the krebs cycle
- more ATP can be made from one molecule of fatty acid compared to one molecule of glucose
What happens during the electron transport chain?
- hydrogen from the krebs cycle is carried to the ETC by hydrogen carriers
- hydrogen is split into into protons and electrons which are charged
- hydrogen ions oxidise to form water with the ellectrons providing energy to resynthesise ATP
- happens in the mitochondria
- produces 28ATP
What is the net gain of ATP from aerobic respiration?
34
Describe oxygen consumption during exercise
- when exercising insufficient oxygen is distributed to the tissues for energy to be provided aerobically because it takes time for the body to respond to the increase in oxygen demand
- results in energy being provided anaerobically to satisfy the demand for energy untill the body can cope
What is maximal and submaximal oxygen deficit?
Submaximal when there is not enough O2 available at the start of exercise to provide all the energy aerobically
Maximal the difference between the estimated oxygen cost of exercise and the accumulated oxygen uptake
Describe oxygen consumption during recovery
- when a performer finishes exercise the oxygen consumption is still quite high
- extra oxygen needs to be taken in to help the performer recover
- consists of 2 main components of EPOC: fast replenishment and slow replenishment stage
What is the breathlessness after exercise referred to as?
Excess post-exercise oxygen consumption (EPOC)
