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AQA A Level PE > 3.1.1.6 - Energy Systems > Flashcards

3.1.1.6 - Energy Systems Flashcards

(complete)

1
Q

What two things does energy depend on?

A

Intensity
Duration

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2
Q

Where does the energy we use for muscle contractions come from?

A

Adenosine triphosphate (ATP)

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3
Q

What does adenosine triphosphate consist of?

A

1 molecule adenosine and 3 phosphates
ATP is stored energy

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4
Q

What is ATP?

A
  • immediate energy
  • high energy bond/compound stored in muscle
  • usable source of energy
  • potential energy
  • reversible reaction
  • exothermic reaction
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5
Q

What is ATPase?

A

The enzyme that breaks down ATP when C02 increases.

It leaves ADP and an inorganic phosphate (Pi)
When this phosphate ion is released, so is energy

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6
Q

How is ATP resynthesised?

A

The body regenerates ADP + Pi back into ATP using certain ‘fuels’, allowing the energy to be used again.

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7
Q

What fuels are involved in resynthesis of ATP?

A

Glycogen: Stored in the muscle and liver. It is converted into glucose before being used for ATP resynthesis. This can be done both aerobically and anaerobically.

Fats: At rest 2/3 of energy requirements are met through breaking down fatty acids. Rich in energy, but require large amounts of 02 to be broken down. Transport in fats is slow so it’s only used in low intensity.

Protein: Contribute the least to the energy yield (only 15%). Used when carbohydrates and fats stores are low.

Phosphocreatine: A chemical stores within the muscle cell. Used within the first 10 seconds of intense exercise.

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8
Q

What 3 pathways are these fuels converted into energy through?

A
  1. The aerobic (oxidative) system
  2. The anaerobic glycolysis system (lactate system)
  3. The ATP-CP system
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9
Q

What energy system(s) would be used if intensity is high/short duration?

A

The anaerobic glycolytic system/ATP system

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10
Q

What energy system would be used is intensity is low/long duration?

A

Aerobic system (anything after 2.5 mins)

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11
Q

How does the aerobic (oxidative) system work?

A

It uses the fuel from glycogen, fats and protein to resynthesise ATP and has 3 stages.

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12
Q

What is the difference between the fuels of glucose, fats and protein in the aerobic system?

A

Glucose is the most efficient way of resynthesis ATP, as it’s oxidation produces 38 molecules of ATP.

When fats (fatty acids) are broken down, they’re reduced to the molecule acetyl coenzyme A. This molecule enters the krebs cycle.

When the proteins (amino acids) are broken down, they too are reduced to the molecule acetyl coenzyme A. This molecule enters the krebs cycle

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13
Q

3 stages of the aerobic system?

A
  1. Glycolysis
  2. The Krebs cycle
  3. The electron transport chain
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14
Q

What occurs in glycolysis? (Oxidative system)

A

Takes place in the sarcoplasm of the muscle cell.
Breaks glucose down into pyruvic acid via the enzyme phosphofructokinase (due to 02 present).
During glycolysis, every 1 molecule of glucose produces 2 molecules of ATP.
Pyruvid acid is then converted into acetyl coenzyme A as 02 is present.
If there isn’t sufficient oxygen present, it will turn into lactic acid.
Acetyl coenzyme A is carried into the Krebs cycle.

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15
Q

What occurs in the Krebs cycle?

A

Takes place in the mitochondria which produces high levels of energy.
As a result of the Krebs cycle, the acetyl groups carried in combine with oxaloacetic acid.
This forms citric acid: citric acid produced then undergoes oxidative carboxylation.

As a result, the following are produced: C02, H20, H+ions (or) hydrogen atoms, 2 ATP.
The hydrogen atoms that enter the third stage of the aerobic system.

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16
Q

What occurs in the electron transport chain?

A

Takes place in cristae of the mitochondria.
Hydrogen atoms enter the electron transport chain where lots of energy is produced - enough to resynthesis 32-34 more ATP.
Consequently, that 1 molecule of glucose/fat/protein has produced 36-38 ATP which is a really high energy yield.

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17
Q

What is beta oxidation?

A

Stored fats can be used in a very similar way to glucose.
Firstly, they must be broken down from triglycerides into glycerol and free fatty acids.
The glycerol and free fatty acid go through the process of beta oxidation (glycolysis for fats).
This forms oxaloacetic acid which combines with Acetyl Coenzyme A.
Once combined with Acetyl Coenzyme A, it can now enter krebs.

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18
Q

Positives of the oxidative system?

A
  • 1 molecule of glucose/fat/protein has produced 36-38 ATP
  • a really high energy yield
  • lots of energy over a long period of time
  • no fatiguing by-products
  • high stored of glycogen and triglyceride meaning exercise lasts for a long time
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19
Q

Negatives of aerobic system?

A
  • system can only be used during submaximal activities
  • energy production is not rapid, will take minutes
  • fatty acid transportation in muscles is low
  • fatty acids require 15% more oxygen to be broken down
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20
Q

How does the anaerobic glycolytic system work?

A

The anaerobic glycolytic system:
- provides energy for high intensity activity
- resynthesises ATP which involves the breakdown of glucose
- depends on the intensity of the activity
- has a duration that depends on the fitness of the athlete (lasts between 8/10 seconds and 3 minutes (e.g.400m))
- takes place in the sarcoplasm

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21
Q

How does the anaerobic glycolytic system provide energy?

A

Uses the following enzymes to break down glucose:
Glycogen phosphorylase - breaks glycogen into glucose
Phosphofructokinase - breaks glucose into pyruvic acid
Lactate dehydrogenase (LDH) - breaks pyruvic acid down into lactic acid

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22
Q

Positives of the anaerobic glycolytic system?

A
  • ATP resynthesised quickly due to fewer reactions
  • Lasts longer than ATP-PC system
  • If oxygen present, lactic acid is converted back to glycogen
  • Used during a sprint finish for extra bursts of energy
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23
Q

Negatives of anaerobic glycolytic system?

A
  • Lactic acid is the by-product
  • Accumulation of lactic acid denatures enzymes
  • Prevents the rate at which chemical reactions can take place
  • Small energy yield (2ATP)
  • Energy from anaerobic conditions is low (5%) compared to energy from aerobic conditions (95%)
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24
Q

How does the ATP-PC system work?

A
  • The breakdown of ATP and the increase in the volume of ADP triggers an enzyme known as Creatine Kinase.
  • This initiates the breakdown of PC into Phosphate and Creatine in the sarcoplasm of the muscles.
  • Being an exothermic reaction, this provides the energy required to resynthesise ATP at a fast rate.
  • It’s rapid availability is important for a single maximal movement e.g. long jump/high jump take off.
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25
Q

Summary of ATP-PC system?

A
  • stores are phosphocreatine limited
  • ATP system lasts for 2 seconds
  • phosphocreatine lasts for 6-8 seconds meaning energy is provided for this duration
  • can only replenish itself during low intensity exercise and when oxygen is present

For every 1 molecule of phosphocreatine broken down, 1 ATP is resynthesised.

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26
Q

Positives of ATP-PC system?

A
  • energy released quickly
  • ATP resynthesised quickly
  • allows high intensity to be completed again in a short space of time
  • no waste by-products formed
  • can extend duration of system through creatine supplementation
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27
Q

Negatives of ATP-PC system?

A
  • limited phosphocreatine stores
  • can only be completed for 8-10 seconds
  • full recovery takes 2-3 minutes
  • PC resynthesis can only take place in the presence of oxygen
  • only one molecule of ATP can be resynthesised for every one molecule or PC (poor energy yield)
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28
Q

What does the energy continuum allow us to see?

A
  • which energy system is used for different types of activity
  • contribution of each system depending on intensity/duration
  • that energy systems don’t work in isolation but 1 is predominant
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29
Q

What do energy thresholds represent?

A

The time when one system becomes exhausted, and then the other takes over.

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30
Q

What is the ATP-PC/anaerobic glycolytic threshold?

A

The point at which the ATP-PC energy system is exhausted and the anaerobic glycolytic system takes over.
This happens at 10 seconds.

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31
Q

What is the anaerobic glycolytic/aerobic threshold?

A

The point at which the anaerobic glycolytic system is exhausted and the aerobic system takes over.
This happens at 3 minutes.

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32
Q

Characteristics of slow twitch (type 1) muscle fibres (and ATP produced)?

A
  • used for low/medium intensity
  • used for aerobic respiration
  • main pathway for ATP production is the aerobic system

Slow twitch produces up to 36 ATP - production is slow, but you are less likely to fatigue.

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33
Q

Characteristics of fast twitch (type 2) muscle fibres (and ATP produced)?

A
  • recruited for high intensity
  • anaerobic respiration is main energy pathway
  • a much quicker process (does not require oxygen)

Only produces 2 ATP per mole of glucose - fatigue quicker due to buildup of lactic acid (anaerobic glycolysis)

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34
Q

What is oxygen consumption?

A

The term given to the amount of oxygen we use to produce ATP

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35
Q

What is oxygen consumption often referred to as?

A

VO2

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36
Q

What is oxygen consumption at rest?

A

0.3-0.4 li/min

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37
Q

What is the average maximal oxygen consumption?

A

3-6 li/min

This is our VO2 max

38
Q

VO2 max definition?

A

The maximal amount of oxygen taken up and used by the muscles per minute.

39
Q

What is sub-maximal oxygen deficit?

A

When there is not enough oxygen present at the start of exercise to provide all the energy (ATP) aerobically.
Energy is provided anaerobically as a result.

40
Q

Why does sub-maximal oxygen deficit occur?

A
  • It takes time for the circulatory system to respond to the increased demand for oxygen.
  • The mitochondria too takes time to respond to the rate of aerobic respiration.
41
Q

Define EPOC

A

Post-exercise oxygen consumption

  • this is our recovery phase
  • when we recover from any activity, we go into EPOC
42
Q

How do we know if someone is in EPOC?

A

→ faster and deeper breathing rate

→ they are consuming excess oxygen post exercise

43
Q

What are the 2 main parts to EPOC?

A

Fast component
Slow component

44
Q

What is involved in the fast (alactacid) component of EPOC?

A
  • faster and deeper breathing after exercise
  • recovery achieved within 2-3 mins
  • takes 3-4L of extra oxygen to complete this component

2 most important things about this component:

→ Resynthesising ATP + PC stores (2-3 mins)
→ Replenishing myoglobin stores

45
Q

What is involved in the slow (lactacid) component of EPOC?

A
  1. Removal/buffering of lactic acid
  2. Maintenance of breathing + HR
  3. Glycogen replenishment
  4. Increase in body temperature
46
Q

How is lactic acid removed in the slow component?

A

4 ways:
- When O2 present: Lactic acid → pyruvate → CO2 +H2O in the inactive muscles and organs - this can then be used by the muscles as an energy source.

  • Cori cycle: Transported in the blood → liver, then converted into blood glucose and glycogen
  • Converted into protein
  • Removed in sweat and urine
47
Q

How long does lactic acid take to be removed in the slow component?

A

Full recovery can take 1/2 hours depending on intensity/duration

48
Q

How does the fast (alactacid) component work?

A
  • uses the extra 02 taken in during recovery to release ATP + PC and to re-saturate myoglobin with O2
  • complete restoration of PC takes up to 3 mins, 50% of stores can be replenished after 30 secs
  • used approx. 3L of O2 during this time
49
Q

Why does maintenance of breathing and HR require extra oxygen?

A

To provide energy for the respiratory and cardiac muscles.

50
Q

How does maintenance of breathing and HR aid recovery? (Slow component)

A
  • extra oxygen replenishes ATP + PC stores
  • re-saturates myoglobin
  • removes lactic acid
51
Q

What does glycogen replenishment depend on? (Slow component)

A

→ Replenishment of glycogen stores will depend on when and how much carbohydrate is consumed after exercise.
→ If within the first hour after high duration, short intensity - we can restore a significant amount of glucose

52
Q

How do we restore a significant amount of glucose?

A
  • a significant amount of glucose can be restored as lactic and converted back to blood glucose and glycogen in the liver via the Cori cycle
  • eating a high carbohydrate meal within the first hour (commonly chocolate milk)
53
Q

How does an increase in body temperature aid recovery? (Slow component)

A
  • when temperature remains high, respiratory rates remain high
  • this helps the performer to take in more oxygen during recovery
54
Q

How is lactic acid produced?

A

Anaerobic glycolysis produces lactic acid in glycolysis.
Higher intensity → more lactic is produced

55
Q

How does lactic acid break down to create lactate?

A

Lactic acid → break down → releases hydrogen ions (H+) → combines with sodium ions (Na+) or potassium ions (K+) → forms the salt lactate

56
Q

Impact of lactate accumulation?

A

As lactate accumulates, more hydrogen ions are present.
An increase in hydrogen ions causes an increase in acidity

This increase in acidity denatures enzymes meaning glycogen can not be broken down as efficiently so fatigue sets in.

Lactate moves from the muscle to blood (blood lactate can be measured)

57
Q

Define lactate threshold

A

The point at which lactic acid starts to accumulate in the blood.
As exercise intensity increases, oxygen production is reduced and we are unable to break down lactate.

58
Q

What is OBLA

A

Onset of blood lactate accumulation

Also known as the accumulation of lactate in the blood

59
Q

What is lactate threshold and what is it’s relationship with VO2 max?

A

Lactate threshold is expressed as a percentage of VO2 max.

→ Average performers may have a lactate threshold that is 50-60 percent of their VO2 max, whereas for elite performers, the threshold may be more like 70,80 or 90% of their VO2 max.

→ The higher the VO2 max, the more the delay in lactic acid build-up so as VO2 max increases, so does lactate threshold.

→ Trained athletes can exercise for longer periods at the same/higher intensity compared to an untrained athlete.

60
Q

When does OBLA start?

A

→ Starts at 4mmol/litre OR 2mmol/litre above resting levels
→ Occurs as body is unable to provide enough oxygen to break down lactic acid

61
Q

How much lactate can be found in the blood at rest?

A

Approximately 1-2 millimoles per litre of lactate can be found in the blood.

62
Q

What fitness test is good to illustrate OBLA?

A

The multi-stage fitness test

63
Q

Factors affecting the rate of lactate accumulation?

A

→ 𝐈𝐧𝐭𝐞𝐧𝐬𝐢𝐭𝐲 𝐨𝐟 𝐞𝐱𝐞𝐫𝐜𝐢𝐬𝐞 : higher the intensity, the greater the demand for energy and the faster OBLA occurs - glycogen broken down with no O2 into pyruvic acid = lactic acid.

→ 𝐅𝐢𝐭𝐧𝐞𝐬𝐬 𝐨𝐟 𝐭𝐡𝐞 𝐩𝐞𝐫𝐟𝐨𝐫𝐦𝐞𝐫: physiological adaptive responses due to training e.g. greater amount of mitochondria and myoglobin = greater capillary density, improved gaseous exchange (both delay OBLA).

→ 𝐕𝐎𝟐 𝐦𝐚𝐱 𝐨𝐟 𝐭𝐡𝐞 𝐩𝐞𝐫𝐟𝐨𝐫𝐦𝐞𝐫

→𝐑𝐚𝐭𝐞 𝐨𝐟 𝐛𝐥𝐨𝐨𝐝 𝐥𝐚𝐜𝐭𝐚𝐭𝐞 𝐫𝐞𝐦𝐨𝐯𝐚𝐥: If rate of lactate removal is equivalent to the rate of lactate production, then the concentration of blood lactate remains constant.

→ 𝐌𝐮𝐬𝐜𝐥𝐞 𝐟𝐢𝐛𝐫𝐞 𝐭𝐲𝐩𝐞𝐬: if slow twitch used, OBLA is delayed as they produce less lactate.

→ 𝐑𝐞𝐬𝐩𝐢𝐫𝐚𝐭𝐨𝐫𝐲 𝐞𝐱𝐜𝐡𝐚𝐧𝐠𝐞 𝐫𝐚𝐭𝐢𝐨: The ratio of CO2 produced compared to O2 consumed - the closer the value to 1:0, the greater the chance of lactate accumulation.

→ 𝐋𝐚𝐜𝐭𝐚𝐭𝐞-𝐩𝐫𝐨𝐝𝐮𝐜𝐢𝐧𝐠 𝐜𝐚𝐩𝐚𝐜𝐢𝐭𝐲

64
Q

How does lactate-producing capacity work?

A

(For sprint/power athletes)
Elite sprinters have much better anaerobic endurance than untrained as the body adapts to high levels of lactate.

A process known as buffering enables them to remove lactate at a greater rate meaning elite athletes can work at a higher intensity for a longer duration without fatigue setting in.

The following adaptations occur as a result of training: number and size of mitochondria, associated oxidative enzymes, increased capillary density and more myoglobin.

65
Q

Average VO2 max for males and females?

A

Males: 45-55 ml/kg/min
Females: 35-44 ml/kg/min

66
Q

Factors affecting VO2 max/aerobic power?

A
  • Training
  • Differences in age
  • Genetics
  • Body composition
  • Lifestyle
  • Gender
  • Physiological
67
Q

How does training affect VO2 max?

A

VO2 max can be improved by up to 10-20% following a period of aerobic training including:
- continuous
- fartlek
- aerobic interval

68
Q

How does differences in age affect VO2 max?

A

As we get older our VO2 max declines as our body systems become less efficient.

69
Q

How does body composition affect VO2 max?

A

A higher percentage of body fat decreases VO2 max

70
Q

How does lifestyle affect VO2 max?

A

Smoking, sedentary lifestyle, poor diet and poor fitness can all reduce VO2 max values.

71
Q

How does gender affect VO2 max?

A

Men generally have approx. 20 per cent higher VO2 max than women.

72
Q

How does genetics affect VO2 max?

A

Inherited factors of physiology could limit possible improvement.

73
Q

What physiological factors affect VO2 max?

A
  • Increased maximum cardiac output
  • Increased stroke volume/ejection fraction/cardiac hypertrophy
  • Greater HR range
  • Less O2 used for cardiac muscle so more is available at the muscles
  • Increased haemoglobin and RBC count
  • Increased myoglobin content
  • Increased capillarisation around the muscles
  • Increased stores of glycogen and triglycerides
  • Increased number and size of mitochondria
  • Increased surface area of alveoli
  • Increased lactate tolerance
74
Q

What are the measurements of energy expenditure?

A
  1. Indirect Calorimetry
  2. Lactate sampling
  3. Respiratory exchange ratio
  4. VO2 max test
75
Q

What is indirect calorimetry and how does it work?

A

It measures the production of CO2 and the consumption of O2.

  • Provides an accurate estimate of energy expenditure through gas exchange.
  • Measures the production of CO2 and O2 at both rest and during exercise.
  • Enables the performer to find the main fuel being used (e.g. fats/carbohydrates).
  • It is an accurate test which provides a precise calculation of VO2 and VO2 max.
76
Q

What is lactate sampling and how does it work?

A

(used predominantly by runners, swimmers and rowers)
Involves taking blood samples to measure the level of lactic acid in the blood.

  • Provides accurate and objective measures by measuring OBLA/lactate threshold which occurs at 4mmols.
  • The higher the intensity at which OBLA occurs, the fitter the athlete.
  • Ensures training is at the correct intensity, gives an idea of fitness levels and enables the coach to monitor improvements over time.
77
Q

What is respiratory exchange ratio and how does it work?

A

Measures the ratio of CO2 released compared to O2 used by the body.

  • Estimates the use of fats and carbohydrates used during exercise/calculates energy expenditure.
  • Requires the performer to be attached to a gas analyser while on a treadmill or cycle ergometer.
  • Enables accurate readings.
  • Tells if performer is working aerobically or anaerobically and indicates which energy system is being used.
78
Q

What do different RER (Respiratory exchange ratio) values mean?

A

RER close to 1 - using carbohydrates
RER close to 0.7 - using fats (aerobic)
RER greater than 1 - anaerobic respiration (more CO2 produced than O2 consumed)

79
Q

What is a VO2 max test and how does it work?

A

Sports scientists use equipment in laboratories to produce valid and reliable results using gas analysis.

  • Involves increasing intensities on a treadmill, cycle ergometer or rowing machine.
  • Perform until exhaustion while the air expired is calculated by computer software.
  • The volume and concentration of O2 in expired air is measured and compared with the percentage of O2 in the atmosphere to see how much O2 has been used.
80
Q

What are other non-scientific ways to test VO2 max?

A
  • Multi-stage fitness test
  • Harvard step test
  • Cooper’s 12 minute run

However, these only provide a prediction of VO2 max.

81
Q

What specialist training methods have an impact on energy systems?

A

Altitude training
HIIT
Plyometrics
SAQ (speed, agility, quickness)

82
Q

What is involved in altitude training?

A
  • Over 2500m/8000 feet above sea level.
  • Lasts for 30 days.
  • 3 stages: acclimatisation, primary training and recovery.
  • Partial pressure of O2 is lower.
  • Not as much O2 diffuses into the blood so haemoglobin is not as fully saturated, decreasing oxygen carrying capacity of blood.
  • Decreases aerobic performance leading to quicker onset of anaerobic respiration.

Alternatives: hypoxic tents, altitude tents, oxygen tents etc

83
Q

Evaluation of altitude training?

A

:)
- Body produces EPO
- Increased RBCs
- Increased capillarisation
- Increased conc. of haemoglobin
- Increased tolerance to lactic acid/buffering
- Benefits last up to 14 days

:(
- Altitude sickness
- Hard to train at same intensity meaning loss of fitness/detraining could occur
- Benefits lost within a few days back at sea level
- Body produces limited EPO
- Psychological issues due to travel e.g. homesickness

84
Q

What is involved in HIIT (High intensity interval training)?

A
  • Short duration(20s intense)
  • Anaerobic - working at anaerobic threshold
  • 10s recovery (aerobic)
  • 6-8 cycles
85
Q

Variations of HIIT?

A
  • different numbers of high intensity work intervals
  • different numbers of low intensity recovery intervals
  • different lengths of time for work and recovery
  • different exercise intensity for the recovery (low/medium)
86
Q

Benefits of HIIT?

A
  • Increased anaerobic capacity
  • Increased fat burning potential
  • Reduced body fat
  • Motivational as it is short duration
87
Q

What is involved in plyometrics?

A

Involves hopping/jumping/bouncing/depth jumping.

  • Aims to develop power
  • Activates and develops fast twitch (type 2) muscle fibres
  • Works on the idea that muscles generate more force if they have previously been stretched
  • The stretch of a muscle before contraction = stretch shortening cycle
88
Q

What are the stretch shortening cycle stages and how do they work?

A
  1. Eccentric phase → (pre-loading phase)
    - mechanically on landing the muscle performs an eccentric contraction where it lengthens under tension.
  2. Amortisation phase
    - time between the eccentric and concentric muscle contractions
    - needs to be as short as possible so stored energy is not lost through heat
    - stored energy from eccentric contraction is then available for concentric phase
  3. Concentric contraction → (muscle contraction)
    - uses the stored energy
    - in doing so, increases the force of the contraction
89
Q

How is the energy stored in the amortisation phase?

A
  • during eccentric contraction, stretch reflex activated
  • detected by muscle spindles
  • proprioceptors send nerve impulses to spinal cord/CNS
  • elastic energy is stored
  • protects over stretching of muscles/avoids injury
90
Q

What is involved in SAQ?

A

Improves multi-directional movements through the development of the neuromuscular system

  • involves increasing the speed in which muscle contracts
  • all energy for all activities provided anaerobically at maximum force, high speed
  • used by sprinters but games players may also use e.g. basketball players
91
Q

What drills are involves in SAQ?

A
  • zig-zag runs
  • foot ladders
  • often ball introduced to make it sport-specific
92
Q

Benefits of SAQ?

A
  • Increased muscular power
  • Improved kinaesthetic and spatial awareness
  • Improved motor skills/techniques
  • Improved reaction time

AQA A Level PE (19 decks)

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