A level PE energy systems Flashcards
Identify the different Energy systems
ATP PC
glycolytic
aerobic
Describe the ATP PC system
In the sarcoplasm high intensity only lasts a few seconds (2 to 10 secs) used to resynthesises ATP from ADP PC = phosocreatine PC -> P + C + energy Enzyme creatine kinase ADP + P -> ATP yield 1 mole ATP no by products within 20 secs 50% of PC is restored
Describe the Glycolytic system including the relevant enzymes
In the sarcoplasm
high intensity short term exercise
Fuel is glycogen/glucose
enzyme glycogen phosphorylase (GPP) glycogen _. glucose
phosphofructokinase(PFK) glucose -> pyruvic acid
lactate dehydrogenase (LDH) Pyruvic acid -> lactic acid
can last up to 3 mins depending on intensity of exercise
2 molecules of ATP are used but 4 are produced therefore a net gain of 2ATP
yield 1 mole glycogen = 2 moles ATP
by product lactic acid
leads to OBLA
GPP converts glycogen to glucose if levels in blood stream fall
two stages
1 glucose to pyruvic acid (PFK)
2 pyruvic acid to lactic acid (LDH)
Describe the Aerobic energy system
What are the different stages called?
In the sarcoplasm & mitochondria Aerobic Sub maximal intensity Fuels glycogen/ glucose / triglycerides Enzymes GPP, PFK, co-enzymeA, lipase Yield 1 mole glycogen gives 38 moles ATP Duration from 3 mins by products H2O CO2
Aerobic glycolysis
Krebs cycle
Electron transport chain
What is the Energy continuum?
The contribution that each of the energy systems during exercise. Depends on duration and intensity but usually all will contribute just to a greater or lesser extent.
first 2 secs ATP HIGH INTENSITY
2secs to 10 secs ATP/PC HIGH INTENSITY
10 secs to 3 mins glycol systems HIGH INTENSITY
over 3 mins aerobic system LOW_MODERATE INTENSITY
Threshold the point at which an athlete moves from one system to another
ATP/glycolic system threshold
glycolic/aerobic threshold
Practical example energy continua
Football
player sprints out on the whistle uses stored ATP for first 2 secs then utilises ATP/PC system. Player dribbles the ball towards the goal at high speed, after 10 secs will utilise the glycolic system as the PC stores run out. Player loses possession and sprints back after the opposition, still using glycolic system. Ball goes out of player and player tracks back to position at a jogging pace, lower intensity means that aerobic system is now predominant.
Describe Recovery in relation to the different stores and explain it’s importance in high energy games
PC stores take 10 secs to deplete but replenished quickly (50% after 30 secs, 100% after 3 mins)
Oxygen which is stored in myoglobin in the muscles also relinked after 3 mins of rest or low intensity exercise
Recovery important in high intensity games such as basketball and netball. Both games played in shorter quarters to allow recovery. Also bball has timeout for the same reason and to prevent OBLA
What is OBLA?
Onset blood lactate accumulation
occurs at about 4mmol/l
causes fatigue, muscle pain.
What is the Work to relief ratio
Ratio of high intensity to low intensity or rest
Having sufficient breaks or lower intensity exercise allows
lactic acid to be broken down and removed. During intermittant exercise lactic acid builds up during high intensity bouts then is partially cleared in the relief interval enabling the performer to work for longer periods.
Taking on water and glucose during longer periods of exercise helps to maintain levels during longer periods of aerobic activity such as distance running or cycling.
How are the energy systems affected by fitness?
Higher aerobic capacity(VO2 max) enables athlete to use more oxygen increasing the intensity at which they can perform before OBLA is reached.
In trained athletes Oxygen arrives onsite earlier than in untrained reducing the time spent in the glycolic system and therefore the build up of lactic acid.
More oxygen allows more use of FFA’s (free fatty acids) these need 15% more oxygen to break down than glucose. Trained athletes can use FFA’s meaning that glucose stores can be conserved for higher intensity activity therefore increasing duration.
What are the Factors affecting the relative contribution of the energy systems
- Position of player, goalkeeper mainly aerobic, ATP-PC system for goal kicks, saves etc whereas midfielder uses all three.
- Structure of the game, field games (rugby, hockey, football) large pitch therefore increases use of aerobic system, smaller courts (netball, basketball, squash, increases use of anaerobic systems as smaller duration higher intensity work.
- Level of competition, tougher competition will mean increased use of anaerobic over the aerobic system.
- Tactics and strategies, man to man marking requires more use of the anaerobic system than zonal marking.
How are the Energy systems affected by training?
HIT training combined with aerobic training at the top end of the threshold improves buffering capacity, removal of lactic acid and recovery rates. Improves strength endurance and the efficiency of the glycolic system.
Aerobic training will improve the aerobic energy system by increasing VO2 max, size and density of mitochondria in muscles and SO fibre recruitment.
Energy systems and diet
Glucose and bicarbonate supplements pre and post match maximise stores of glycogen and increase buffering capacity, thus delaying OBLA.
Glycogen (carb) loading increases glycogen stores for an event and combined with caffeine and nitrates maximise glycogen stores and use of triglycerides, increasing duration of performance.
A football player uses all the different energy systems to resynthesise ATP during a game. Critically evaluate the energy systems that the footballer would use to resynthesise ATP during the game.
Explain the factors that might affect when each energy system is used by the footballer. [20]
- ATP is the only useable source of energy in the body/ energy currency of the body
stores last up to 2 seconds/ 1 maximal contraction
enzyme ATPase breaks down ATP to release energy
high energy bonds between the adenosine and phosphate elements
(ATP/ PC System) - ATP can be resynthesised via ATP/PC system/alactic system/PC system
involves coupled reactions
PC is broken down into P + C + energy
Energy released + ADP + P –> ATP
Site = muscle cell sarcoplasm
Enzyme = creatine kinase
Increase in ADP stimulates release of enzyme creatine kinase - A football player would use this system to resynthesise ATP when working at high intensity for under 10 seconds
Examples could include sprinting for ball, jumping for header, kicking ball to clear - An advantage of this system is that there are no fatiguing by products produced
allows for the quick re synthesis of ATP/ few reactions
doesn’t need oxygen or no delay for oxygen
PC can be quickly re synthesised (so recovery is quick)/
50% recovery in 30 seconds/100% recovery in 180 seconds
PC is readily available in the muscle - A disadvantage of this system is that only small amounts of fuel is stored in the muscle cell (PC)
low energy yield/only 1 ATP re synthesised
can only provide energy for short period of time/2-10 seconds(Glycolic system)
- ATP can be resynthesised via oanaerobic glycolysis
Glucose is (partially) broken down into pyruvic acid
by the enzyme phosphofructokinase (PFK)
This is further broken down into lactic acid
by the enzyme lactate dehydrogenase (LDH)
Site= muscle cell sarcoplasm
Glucose is stored as glycogen
Glycogen is broken down by the enzyme glycogen phosphorylase (GPP) into glucose
Drop/decrease in PC stimulates release of PFK/GPP - A football player would use this system to resynthesise ATP when working at high intensity for up to 10 sec- 2mins
Examples could include chasing a through ball a number of times or racing down the wing and tracking back - An advantage of this system is that there is a large potential fuel store of glycogen available (stored in muscles and liver)
requires few reactions
can work anaerobically/in the absence of oxygen/no delay for oxygen
can provide energy quickly/faster/quicker (than the aerobic energy system)
makes 2 moles of ATP or more ATP than ATP/ PC system - A disadvantage of this system is that it produces the by–product lactic acid
Causes fatigue
reduces pH/inhibits enzyme action
stimulates pain receptors
(relatively) low yield of ATP (in comparison to aerobic system)
longer recovery
not as quick as ATP/ PC system(Aerobic system)
- ATP can be resynthesised via Aerobic system/oxidative system
Has 3 stages/stage 1 = aerobic glycolysis/stage 2 = Krebs cycle/stage 3 = electron transport chain
(ETC)
Stage 1 site = muscle cell sarcoplasm. Glucose is broken down into pyruvic acid This combines with
coenzyme A to form Acetyl CoA
Stage 2 site = matrix of the mitochondria. Carbon Dioxide is produced Hydrogen atoms are removed
(oxidised). Use/breakdown of fats/FFAs
Stage 3 site = cristae of the mitochondria. Hydrogen atoms combine with NAD & FAD. Carried along the
ETC Hydrogen electron splits from the hydrogen atom and combines with oxygen to form water - A football player would use this system to resynthesise ATP when working at low/ moderate intensity
Examples could include jogging back into position , recovery phase - An advantage of this system is that it has a large energy yield of ATP/34-38 ATP
2 in anaerobic glycolysis, 2 in Krebs cycle/32-34 in the electron transport chain
Large potential stores of glycogen and FFAs
no fatiguing by-products are produced/carbon dioxide & water easily removed
able to work for long periods of time
fats can also be used / provide more energy - A disadvantage of this system is that it is a slower rate of ATP resynthesis
cannot instantly resysnthesise ATP at start of exercise due to delay of oxygen from the CV system
therefore using another system is essential
requires more oxygen/15% more to break down free fatty acids (FFE’s)/fats
more complex series of reactions/aerobic glycolysis & Krebs cycle & electron transport chain
not suitable for high intensity, short duration work. - A footballer would use all three energy systems during a game/ energy continuum
Due to the different intensity of the activity within the game
Due to the different duration of specific activities within the game
- The systems do not work in isolation/they interact to resynthesise ATP
energy system thresholds/the point at which one system is taken over by another as the predominant
system
exercise intensity and duration of the activity being undertaken will affect which energy system is predominant - The fitness/amount of training done will affect which system is used
Anaerobic training means ATP/PC/lactate thresholds/OBLA delayed
Due to increased stores of ATP/PC/glycogen
Increased tolerance to lactic acid
Aerobic training means more efficient CV and respiratory systems/ can use FFAs earlier - Availability of oxygen will affect which system is used
• If oxygen is available then aerobic system will be used
• If oxygen is not available then the LA system/ATP/C system is used - The fuel available will determine which energy system is in use
• If there are sufficient PC stores then the ATP/PC energy system
• PC stores depleted then glycogen is used/lactic acid system is used
• If glycogen is present then the aerobic system will be the predominant system if the exercise is of
moderate intensity (oxygen is also required)
• The greater the liver/muscle glycogen stores the longer the aerobic system can be the predominant
system (even at a higher intensity exercise)
• As the duration of the exercise continues there is a greater breakdown of fats/ fatty free acids. This
requires more oxygen therefore if fats are the available fuel then the aerobic system would be the predominant energy system - Importance of game/state of game/tactics used may affect which system is predominant • E.g. Cup final players may work at higher intensity/more anaerobic
- E.g If 1-0 down with 10 minutes to play in cup match intensity will be higher/more anaerobic • E.g. Winning 5-0 or against poor opposition intensity may drop/more aerobic
- E.g. high tempo/pressing style means more anaerobic.
Describe Aerobic glycolysis
In the sarcoplasm
PFK converts glucose to pyruvic acid
yield 2 moles ATP
Glycogen is converted to glucose by GPP which allows this to continue over time
Because there is sufficient oxygen the pyruvic acid is converted into acetyl co A instead of lactic acid the enzyme is coenzyme A
