Edexcel A Level Physical Education A 9536
Edexcel Examinations
A Level Physical Education
A 9536
Unit 6 : Section A
part 1
Scientific Principles of Exercise and Performance
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Unit 6 A.1.1
INDEX
Index
Edexcel A Level Physical Education A 9536
3 - ENERGY - DEFINITIONS
4 - ENERGY CONCEPTS
APPLICATIONS / RATES OF ENERGY EXPENDITURE
5 - INVESTIGATIONS
RUNNING UP STAIRS (Margaria Staircase Test)
ENERGY VALUE OF FOOD EATEN
6 - ENERGY CONCEPTS
7 - METABOLISM - ENERGY METABOLISM
BASAL METABOLIC RATE (BMR) / TOTAL METABOLIC RATE
8 - MOTOR NEURONE STRUCTURE
CELL BODY / DENSRITES / AXON
9 - TRANSMISSION OF NEURAL IMPULSE
AN ACTION POTENTIAL
10 - TRANSMISSION OF NEURAL IMPULSE - CONDUCTION OF
ACTION POTENTIAL / MYELIN SHEATH
11 - TRANSMISSION OF NEURAL IMPULSE
The MOTOR END PLATE / FUNCTION / ACTION
12 - IMPULSE TRANSMISSION AT A NEUROMUSCULAR JUNCTION
13 - PRODUCTION OF COORDINATED MOVEMENT
MOTOR NEURAL FIRING PATTERNS / SINGLE FIBRE TWITCH
WAVE SUMMATION
14 - PRODUCTION OF COORDINATED MOVEMENT
MOTOR NEURAL FIRING PATTERNS / MULTIPLE FIBRE
TWITCHES / SPATIAL SUMMATION
15 - PRODUCTION OF COORDINATED MOVEMENT
MOTOR NEURAL FIRING PATTERNS / MULTIPLE FIBRE
TWITCHES / GRADATION OF CONTRACTION
16 - CONTROL OF COORDINATED MOVEMENT
THE CEREBELLUM / THE LEARNING OF SPORTS SKILLS
17 - CONTROL OF COORDINATED MOVEMENT
RECIPROCAL INNERVATION
18 - SKELETAL MUSCLE ANATOMY
TENDON / CONNECTIVE TISSUE / FASCICULI / MUSCLE FIBRE
/ MYOFIBRIL / SARCOMERE
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19 - SKELETAL MUSCLE ANATOMY - STRUCTURE / PHYSIOLOGY
20 - SKELETAL MUSCLE ANATOMY - STRUCTURES
SARCOPLASMIC RETICULUM / TROPOMYOSIN
TROPONIN
21 - STRUCTURE and PHYSIOLOGY of MUSCLE CELL
CONTRACTION
STRUCTURE of a SARCOMERE / CONTRACTION
22 - PHYSIOLOGY of MUSCLE CELL CONTRACTION
EXCITATION and CONTRACTION
23 - PHYSIOLOGY of MUSCLE CELL CONTRACTION
RELAXATION
24 - STRENGTH OF MUSCLE CONTRACTION
FACTORS AFFECTING
25 - ATP - ADENOSINE TRIPHOSPHATE
26 - ATP - RESYNTHESIS OF ATP
27 - ATP / PC ALACTIC SYSTEM - THE PC SYSTEM
28 - ATP / PC ALACTIC SYSTEM - THE PC SYSTEM
THE COUPLED REACTION
29 - ATP / PC ALACTIC SYSTEM - THE PC SYSTEM
EFFECT OF TRAINING
30 - THE LACTIC ACID SYSTEM - GLYCOLYSIS
31 - THE LACTIC ACID SYSTEM - EVENTS / SPORTS
EFFECTS OF CONTINUED HIGH INTENSITY EXERCISE
32 - THE AEROBIC SYSTEM
GLYCOLYSIS / KREB’S CYCLE (CITRIC ACID CYCLE)
ELECTRON TRANSPORT CHAIN
33 - THE AEROBIC SYSTEM
34 - THE AEROBIC SYSTEM
AEROBIC RESPIRATION / EXERCISE TYPES
35 - THE ENERGY CONTINUUM
36 - THE ENERGY CONTINUUM
FACTORS AFFECTING PROPORTIONS OF ENERGY SYSTEMS
VARIATION IN CONTRIBUTION OF ENERGY SYSTEMS
Unit 6 A.1.2
Edexcel A Level Physical Education A 9536
Energy Concepts
ENERGY
DEFINITIONS
ENERGY
• is the capacity to do work
WORK
• = force x distance moved
• measured in joules J
CHEMICAL ENERGY
• is energy that is produced by a complex series of chemical reactions
• which can then be made available as :
KINETIC ENERGY
• is energy due to movement
• which results from muscular contractions
POTENTIAL ENERGY
• is stored energy due to gravity
POWER
• is the rate at which energy is used
• the energy used per second
• unit watt W
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Unit 6 A.1.3
Edexcel A Level Physical Education A 9536
Energy Concepts
ENERGY CONCEPTS
APPLICATIONS
• warming-up
• the construction of training
programmes
• prevention of fatigue
• delay of fatigue
• recovery from fatigue
• nutrition
• performance
• bodyweight control
• body temperature maintenance
GENERAL CHARACTERISTICS
• measurement of energy expenditure
DIRECT METHOD
• involves burning of food
• and measuring heat energy produced
INDIRECT METHOD
• involves measurement of oxygen
consumed or oxygen uptake during
exercise
RATES OF ENERGY EXPENDITURE (per kg of body mass)
• above basal requirements kJ kg-1 min-1
sitting at rest
0.14
walking
0.2
jogging / swimming (moderate)
0.6
cycling (moderate)
0.46
vigorous exercise
0.8
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Unit 6 A.1.4
Edexcel A Level Physical Education A 9536
Energy Concepts
INVESTIGATIONS
RUNNING UP STAIRS (Margaria Staircase Test)
• energy gained = weight x height
• power
= energy (joules)
•
time taken (sec)
• answer in watts
ENERGY VALUE OF FOOD EATEN
• calculate full energy value of food eaten
• compared with measured energy output
• results show that only a small proportion of the
energy is converted into useful work
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Unit 6 A.1.5
Edexcel A Level Physical Education A 9536
Energy Concepts
ENERGY CONCEPTS
applications
molecular muscle
cell structures
ATP
definitions
the recovery
process
tem
s
y
ENERGY
1 ATP - PC system
(alactic)
s
syst
em 2
m
te
s
sy
lactic acid system
3
fuel for
exercise
sports activities
and the energy
continuum
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aerobic system
general
characteristcis
Unit 6 A.1.6
Edexcel A Level Physical Education A 9536
Energy Concepts
METABOLISM
ENERGY METABOLISM
• total intake of food sufficient to supply enough energy to :
– keep cells alive
– keep systems working
– meet demands of life
BASAL METABOLIC RATE (BMR)
• this is the least rate of energy usage needed to carry out basic body
functions
• measured after lying down after 8 hours sleep / 12 hours fasting
TOTAL METABOLIC RATE
• sum of BMR + energy required for all daily activities
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Unit 6 A.1.7
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
MOTOR NEURONE STRUCTURE
CELL BODY
• includes nucleus and cytoplasm
• membrane is receptive to stimuli from other
neurones
DENDRITES
• highly branched processes which extend out
from the cell body
• specialised to receive stimuli from sensory
organs or from other neurones
AXON
• conducts nerve impulses to other cells (nerve,
muscle, gland cells)
• special structures include :
– myelin sheath insulates nerve
– nodes of Ranvier are gaps in myelin sheath
where action potential jumps from node to
node
– axon terminal ends with synaptic end bulbs
containing neurotransmitter substances
– enabling action potential to be applied to
adjacent cells
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Unit 6 A.1.8
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
TRANSMISSION of NEURAL IMPULSE
AN ACTION POTENTIAL
• transmission of neural messages along a neurone is an
electrochemical process
• an action potential is initiated when sufficient numbers
of Na+ ions diffuse into the neuron
•
•
•
this depolarises the axon to a
critical threshold level
called the all-or-none law
followed by repolarisation back to
the resting potential
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Unit 6 A.1.9
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
TRANSMISSION of NEURAL IMPULSE
CONDUCTION of an ACTION POTENTIAL in a MYELINATED AXON
• the myelin sheath insulates the axon
• the action potential travels from node to node in a wave-like action
The MYELIN SHEATH offers :
• increased conduction velocity
• less costly in terms of ion run-down
• since ion exchange only occurs at the nodes of Ranvier
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Unit 6 A.1.10
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
TRANSMISSION of NEURAL IMPULSE
The MOTOR END PLATE
FUNCTION
• to transfer an impulse from the motor
neurones to the muscle fibre block
• this causes all muscle fibres attached to this
end-plate to contract
ACTION
• nerve action potential is followed by the
muscle action potential
• a delay of 0.5 milliseconds occurs due to
release of transmitter substances (such
as acetylcholine from synaptic knobs) which
initiate the muscle action potential
• the area of depolarisation travels down
muscle cell passing the entrances to ‘T’
vesicles which secrete Calcium ions needed
to initiate muscle contraction
• each different fibre type (slow twitch, fast
twitch etc) is innervated by a separate and
different type of motor neurone
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The ALL OR NONE LAW
• stimulation of the motor neurone
will result in contraction of ALL the
fibres in that motor unit
SYNAPSE
• a junction where the axon of one
neurone interacts with another
neurone
Unit 6 A.1.11
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
IMPULSE TRANSMISSION at a NEUROMUSCULAR JUNCTION
Ach
= Acetylcholine
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Unit 6 A.1.12
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
PRODUCTION OF COORDINATED MOVEMENT
MOTOR NEURAL FIRING PATTERNS
• all-or-none law
• all fibres associated with a single motor unit are fired at once
• different fibre groups (attached to different motor units) are
fired at different times
SINGLE FIBRE TWITCH
WAVE SUMMATION
• the same fibre group fired repeatedly will build the force
exerted by wave summation
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Unit 6 A.1.13
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
PRODUCTION OF COORDINATED MOVEMENT
MOTOR NEURAL FIRING PATTERNS
MULTIPLE FIBRE TWITCHES
SPATIAL SUMMATION
• different fibre groups are fired in succession to control a movement
• the total force across the space of a muscle is the sum of the effect of different fibre
groups
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Unit 6 A.1.14
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
PRODUCTION OF COORDINATED MOVEMENT
MOTOR NEURAL FIRING PATTERNS
MULTIPLE FIBRE TWITCHES
GRADATION OF CONTRACTION
• refers to the ability of muscle to produce forces
• varying from very light to maximum force or tension
• achieved in two ways :
– increasing the frequency of stimulus (wave summation)
– varying the number of motor units recruited
• example in hockey :
– fine control of movement required for a flick
– as opposed to the maximum effort required for a full hit
TETANIC CONTRACTION
• no time for relaxation between motor unit firing
• causes complete lock up of muscle
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Unit 6 A.1.15
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
CONTROL OF COORDINATED MOVEMENT
THE CEREBELLUM
• the balance of fine and gross control is under the control of the
CEREBELLUM
• to produce smooth coordinated movement, the cerebellum compares
the intended movement with the actual movement (from sensors within
the moving structure)
• if a difference is detected, the cerebellum sends impulses to the
appropriate motor units in the spinal cord which would produce a
correction
THE LEARNING OF SPORTS SKILLS
• in sport, the cerebellum is involved in the learning of fine motor
skills (as in archery) or gross motor skills (as in weight lifting)
• gross movements use leg and arm muscles having about 1000 muscle
fibres associated with one motor unit
• fine movements (of the eyes and fingers for example) require muscles
with far fewer (10 - 100) muscle fibres controlled by a single motor
unit
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Unit 6 A.1.16
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
CONTROL OF COORDINATED MOVEMENT
CONTROL
• control is achieved by changing the frequency of stimulus - wave
summation
• by increasing or decreasing the number of motor units in
operation - gradation of contraction
• and as a result of different motor units being activated in turn
across a muscle - spatial summation
• to enable very small forces to be maintained if required
• and changes in muscle forces to occur
RECIPROCAL INNERVATION
• this is the self-regulation of rhythmic movements between one
muscle and its antagonist
• control of movements requires regulation of relaxation of
antagonists during dynamic activity of an agonist
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Unit 6 A.1.17
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
SKELETAL MUSCLE ANATOMY
TENDON
• dense connective tissue
• attaches muscle to bone
CONNECTIVE TISSUE
• called fascia (epimysium,
perimysium, endomysium)
• holds muscle tissue together
• allows free movement
• stabilises nerves and blood
vessels
FASCICULI
• bundle of muscle fibres
MUSCLE FIBRE
• muscle cell contains many myofibrils
• several nuclei inside sarcolemma
• mitochondria positioned throughout
• sarcoplasm contains fat / glycogen stores, myoglobin, PC, ATP
MYOFIBRIL
• protein filaments
SARCOMERE
• the basic contractile unit
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Unit 6 A.1.18
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
SKELETAL MUSCLE ANATOMY
STRUCTURE
• called STRIPED or STRIATED
muscle
• every muscle cell is long and thin
called a MYOFIBRIL
• this runs lengthways down the muscle
• each muscle cell has several nuclei
just under the SARCOLEMMA
PHYSIOLOGY
• voluntary
• neurogenic
(actively controlled by thoughts
of sportsperson, and innervated by
action of nervous system)
• DEPOLARISATION (in the motor
end plate) stimulates energy release
• this energy provides the work
necessary for muscle contraction
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Unit 6 A.1.19
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
SKELETAL MUSCLE ANATOMY
STRUCTURES INVOLVED
• the motor unit
• VESICLES in cell sarcoplasm pump
out CALCIUM ions (Ca++)
• Ca++ activates ATPase
• this releases energy bond by
ATP -> ADP + Pi + energy
• this occurs in MITOCHONDRIA
SARCOPLASMIC RETICULUM (SR)
• a network of tubules and sacs in muscle cells
• these t-tubules transmit muscle action potential to myofibril
• the SR is also a storage site for Ca++
TROPOMYOSIN
• long protein molecule that covers active myosin sites enabling actin to bind to
myosin during contraction of the muscle
TROPONIN
• a molecule spaced at intervals along actin filaments
• at rest troponin holds the tropomyosin in position to prevent exposure of the
myosin binding sites on actin filaments
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Unit 6 A.1.20
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
STRUCTURE and PHYSIOLOGY of MUSCLE CELL CONTRACTION
STRUCTURE of a SARCOMERE
• the Z lines are the ends of the sarcomere
• which are attached to actin filaments which
comprise the I zone of the relaxed unit
• the myosin filaments lie in between actin
filaments which they just overlap (relaxed)
• the H zone is the space between the ends
of the actin filaments
CONTRACTION
• during contraction the cross-bridges
between the myosin and actin filaments
pull them towards one another
• this increases the overlap and pulls the Z
lines towards one another
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Unit 6 A.1.21
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
PHYSIOLOGY of MUSCLE CELL CONTRACTION
EXCITATION and CONTRACTION
• a neural action potential travels via a motor neurone to
the motor-end plate
• to create a muscle action potential over the muscle fibre’s
sarcoplasm
• and inward along the ‘T’ tubules
• triggering the release of Ca++ from
‘T’
vesicles (located within SR) into the
sarcoplasm
• where it binds to a troponin molecule
on an actin filament
• tropomyosin molecules on the thin
actin filament move exposing actin’s active sites
• energised myosin cross-bridges bind to actin’s active sites
• and use their energy (released from ATP) to pull the thin
actin filaments towards the centre of the sarcomere (called
the power stroke)
• attach, detach, reattach of cross-bridges is called the
ratchet mechanism
• this cycle repeats itself as long as ATP is available
• when fully contracted the H zone disappears
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Unit 6 A.1.22
Edexcel A Level Physical Education A 9536
Molecular Muscle Cell Structures
PHYSIOLOGY of MUSCLE CELL CONTRACTION
RELAXATION
• after the impulse is over, the SR actively pumps Ca++ back
into its sacs
• tropomyosin returns to its position
• blocking actin’s active sites
• muscle fibre returns to its resting length
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Unit 6 A.1.23
Edexcel A Level Physical Education A 9536
Muscle Strength
STRENGTH OF MUSCLE CONTRACTION
FACTORS AFFECTING THE STRENGTH OF MUSCLE CONTRACTION
metabolic condition
(fatigue)
amount of load
(stretch reflex)
STRENGTH OF
MUSCLE
CONTRACTION
recruitment of
motor units
(number of fibres
activated)
initial length of
muscle fibres
(length tension
relationship)
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Unit 6 A.1.24
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
ATP
ATP - ADENOSINE TRIPHOSPHATE
•
•
•
ATP is the energy currency linked to intensity and duration of physical
activity
ATP exists in every living tissue
its breakdown gives energy for all life functions
•
•
•
•
•
•
energy released during tissue respiration is stored in the chemical bonds in ATP
energy is released during the reaction :
ATP --> ADP + Pi + energy
ATPase is an enzyme which facilitates this reaction
ADP is adenosine diphosphate
the reaction is exothermic - it releases energy
•
the supply of ATP in muscle (and other tissue) will only last for 2 seconds if
vigorous exercise is undertaken
therefore ATP needs to be regenerated by other chemical reactions if exercise is
to continue past 2 seconds
•
•
example : an exercise like standing long jump would use energy from stored ATP
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Unit 6 A.1.25
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
ATP
RESYNTHESIS OF ATP
•
•
•
•
ATP is resynthesised from ADP within the following reaction :
energy + ADP + Pi ---> ATP
this is an endothermic reaction - energy is given to the molecule to enable the
reaction to happen
this energy will be derived from food fuels
•
there are 3 main systems by which this resynthesis occurs
ATP - PC system
(alactic)
lactic acid system
resynthesis of ATP from
ADP, Pi and energy
aerobic system
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Unit 6 A.1.26
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
ATP / PC ALACTIC SYSTEM - THE PHOSPHOCREATINE SYSTEM
ATP / PC SYSTEM
•
•
for activity which lasts between 3 and 10
seconds
for high intensity maximum work
•
example : flat out sprinting - 100m sprint
•
no oxygen is needed - ANAEROBIC
•
the chemical reactions within this system are
a coupled reaction
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Unit 6 A.1.27
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
ATP / PC ALACTIC SYSTEM - THE PHOSPHOCREATINE SYSTEM
THE COUPLED REACTION
•
•
ATP is resynthesised via phosphocreatine (PC)
PC is stored in muscle cell sarcoplasm
•
•
•
•
•
the following reactions takes place :
PC ---> Pi + C + energy
energy + ADP + Pi ---> ATP
the two reactions together are called a coupled reaction
these reactions are facilitated by the enzyme creatine
kinase
•
•
the net effect of these two coupled reactions is :
PC + ADP ---> ATP + C
•
PC is recreated in muscle cells during the recovery
process
this requires energy and is an endothermic reaction
•
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Unit 6 A.1.28
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
ATP / PC ALACTIC SYSTEM - THE PHOSPHOCREATINE SYSTEM
EFFECTS OF TRAINING ON THE ALACTIC
ANAEROBIC SYSTEM
•
muscle cells adapt by :
– increase in ATP and PC stores
•
therefore the ATP / PC system provides energy for
slightly longer
•
•
when exercise is taken at maximum effort
the alactic / lactic threshold is delayed
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Unit 6 A.1.29
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
THE
THE LACTIC ACID SYSTEM
• depends on a chemical process called GLYCOLYSIS
• glycolysis is the breakdown of sugar
•
•
carbohydrate is stored as GLYCOGEN in the muscles
and liver
the breakdown of glycogen provides the
energy to rebuild ATP from ADP
•
the breakdown of glycogen in this way is
facilitated by the enzymes glycogen
phosphorylase (GPP),
phosphofructokinase (PFK)
•
this process is ANAEROBIC and takes place
in the SARCOPLASM of the muscle cell
no oxygen is needed
•
•
•
LACTIC ACID SYSTEM
the end product of this reaction (in the
absence of oxygen) is lactic acid
the enzyme facilitating the conversion from pyruvic
acid to lactic acid is lactate dehydrogenase (LDH)
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Unit 6 A.1.30
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
EFFECTS OF CONTINUED HIGH
INTENSITY EXERCISE
• lactic acid accumulates
• this produces muscle fatigue and pain
• the resultant low pH inhibits enzyme
action and cross-bridge formation
• hence muscle action is inhibited
• physical performance deteriorates
THE LACTIC ACID SYSTEM
EVENTS AND SPORTS
• up to 30 - 60 seconds
• 400m run
• 100m swim
• after exercise stops, extra oxygen is
taken up to remove lactic acid by
changing it back into pyruvic acid
• the OXYGEN DEBT
TRAINING
• develops body adaptations :
– the ability to tolerate higher levels of lactic acid
– more glycogen is stored
– the lactic acid / aerobic threshold is delayed
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Unit 6 A.1.31
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
THE AEROBIC SYSTEM
STAGE ONE - GLYCOLYSIS
• this takes place in muscle cell SARCOPLASM
• and is identical to the lactic acid system
• ATP regenerated = 2ATP per molecule of glucose
STAGE TWO - KREB’S CYCLE (CITRIC ACID CYCLE)
• occurs in the presence of oxygen
• taking place in the muscle cell MITOCHONDRIA within the inner fluid filled
matrix
• pyruvic acid (from glycolysis) promoted by enzymes of the citric acid
cycle, or fatty acids (from body fat) facilitated by the enzyme lipoprotein
lipase or protein (keto acids - from muscle) act as the fuel for this stage
STAGE THREE - ELECTRON TRANSPORT CHAIN
• occurs in the presence of oxygen
• within the cristae of the muscle cell MITOCHONDRIA
• hydrogen ions and electrons have potential energy which is released to
produce the ATP
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Unit 6 A.1.32
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
THE AEROBIC SYSTEM
STAGE ONE - GLYCOLYSIS
STAGE TWO - KREB’S (CITRIC ACID) CYCLE
• 2 molecules of pyruvic acid combine with
oxaloacetic acid (4 carbons) and acetyl
coA (2 carbons)
• to form citric acid (6 carbons)
• the cycle produces H+ and electron pairs,
and CO2, and 2 ATP
• fats and proteins enter the cycle
STAGE THREE - THE ELCTRON
TRANSPORT CHAIN
• the H+ and electron pairs have potential
energy
• which is released in a controlled step by
step manner
• oxygen combines with final H+ ions to
produce water and 32 ATP
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Unit 6 A.1.33
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
THE AEROBIC SYSTEM
AEROBIC RESPIRATION
• the net effect is of an endothermic reaction
• glucose + 36 ADP + 36 Pi + 6O2 ---> 6CO2 + 36 ATP + 6 H2O
•
fat fuels produce 2 ATP less than glucose
AEROBIC EXERCISE TYPES
• low intensity, long duration activities
• examples : game of hockey, 800m swim, long distance jog
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Unit 6 A.1.34
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
THE ENERGY CONTINUUM
THE ENERGY CONTINUUM
• this describes the process by which ATP is
regenerated via the different energy
systems
• depending on the intensity and duration
of exercise
•
•
•
each of the alactic, lactic acid and
aerobic systems contribute some ATP
during the performance of all sports
one or other of the energy systems
usually provides the major contribution
for a given activity
the diagram shows approximate
proportions of ATP resynthesised via
aerobic / anaerobic for some sporting
activities
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Unit 6 A.1.35
Edexcel A Level Physical Education A 9536
Energy Systems and the Energy Continuum
THE ENERGY CONTINUUM
OTHER FACTORS AFFECTING THE PROPORTIONS OF ENERGY SYSTEMS
• used in any given exercise activity are :
– level of fitness (whether adaptations to training have included enhancement of
relevant enzymes - which would for example postpone levels of lactate accumulation)
– availability of O2 and food
fuels, for example a high CHO
diet would assist replenishment
of glycogen stores which would
then be available for glycolysis
VARIATION IN CONTRIBUTION OF
ENERGY SYSTEMS
• as time progresses during intense
exercise, the following chart shows
the contribution of the different
energy systems to the resynthesis
of ATP
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Unit 6 A.1.36