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Edexcel A Level Physical Education A 9536
Edexcel Examinations
A Level Physical Education
A 9536
Unit 6 : Section A
part 2
Scientific Principles of Exercise and Performance
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Unit 6 A.2.1
INDEX
Index
Edexcel A Level Physical Education A 9536
3 - MUSCLE FATIGUE
DEPLETION OF ENERGY STORES / FIBRE TYPE / METABOLIC
ACCUMULATION
4 - MUSCLE FATIGUE
INTERRUPTION OF NEUROMUSCULAR EVENTS
ANTICIPATED FATIGUE / BODY FLUID BALANCE
5 - MUSCLE FATIGUE - FLUID INTAKE
6 - EXCESS POST-EXERCISE OXYGEN CONSUMPTION (EPOC)
FACTORS CONTRIBUTING TO EPOC
7 - THE RECOVERY PROCESS
EPOC / AIM OF RECOVERY PROCESS
OXYGEN DEFICIT / DEBT
8 - THE RECOVERY PROCESS
THE ALACTACID COMPONENT
9 - THE RECOVERY PROCESS
IMPLICATIONS FOR INTERVAL TRAINING / EFFECTS OF
TRAINING
10 - THE RECOVERY PROCESS
LACTACID OXYGEN RECOVERY / RECOVERY
11 - THE RECOVERY PROCESS FATE OF LACTIC ACID / THE LACTATE SHUTTLE / BUFFERING
12 - EFFECT OF COOL-DOWN ON LACTIC ACID REMOVAL
REMOVAL OF LACTIC ACID FOLLOWING EXERCISE
13 - RECOVERY OF BODY STORES
RESTORATION OF MUSCLE GLYCOGEN / MYGLOBIN STORES
14 - IMPLICATIONS FOR INTERVAL TRAINING OF LACTACID
RECOVERY
15 - FUEL FOR EXERCISE
A BALANCED DIET / CARBOHYDRATE / FATS / PROTEIN
16 - STORAGE AND RELEASE OF FOOD FUELS
CARBOHYDRATES / GLUCOSE / FATS / FATTY ACIDS
17 - FOOD FUEL USAGE DURING EXERCISE
DURING HIGH INTENSITY EXERCISE / AT REST
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18 - EXERCISE AND FOOD FUEL USAGE
FOOD FUEL USAGE AT REST AND DIFFERNET INTENSITY
AND DURATION
19 - FOOD FUEL UTILISATION DURING EXERCISE
20 - FOOD FUEL USAGE FOR AEROBIC ACTIVITY
FOOD FUEL USAGE / EXERCISE INTENSITY / DURATION
21 - FOOD FUEL USAGE FOR AEROBIC ACTIVITY
SOURCES OF FUELS
22 - NUTRITION AND EXERCISE - CARBOLOADING
23 - NUTRITION AND EXERCISE - CARBOLOADING
IMPORTANCE OF HIGH GLYCOGEN CONTENT
24 - NUTRITION AND EXERCISE
PRE / POST / DURING COMPETITION NUTRITION
25 - WATER BALANCE
26 - NUTRITION AND EXERCISE - FLUID INTAKE
27 - NUTRITION AND EXERCISE - DIETARY MANIPULATION
28 - FOOD FUEL UTILISATION DURING ANAEROBIC ACTIVITY
HIGH INTENSITY 8 seconds / 60 seconds
29 - RESPONSE TO EXERCISE and TRAINING on the ENERGY
SYSTEMS - and your IPP
Unit 6 A.2.2
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
MUSCLE FATIGUE
MUSCLE FATIGUE
• a reduction of muscular performance
• an inability to maintain expected power output
DEPLETION OF ENERGY STORES
• depletion of PC and muscle / liver glycogen stores
• fatigue in marathon runners is due to depletion of muscle glycogen in both ST
and FT fibres
FIBRE TYPE
• FT muscle fibres have low aerobic capacity
• therefore quickly fatigue during maximal activity
METABOLIC ACCUMULATION
• accumulation of lactic acid and CO2 in muscle cells
• hence increase in H+ ions (decrease in pH)
• inhibits enzyme action (both aerobic and anaerobic) required for ATP
regeneration
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Unit 6 A.2.3
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
MUSCLE FATIGUE
MUSCLE FATIGUE
• is caused by :
– depletion of energy stores
– accumulation of metabolites (lactic acid / CO2)
– low energy stores in certain fibre types
• which in turn cause :
INTERRUPTION OF NEUROMUSCULAR EVENTS
• decrease in Calcium ion (Ca++) availability at motor end-plate
• and failure of Acetylcholine generation mechanism
• which delay release and synthesis of Acetylcholine which reduces transmission of
action potential to skeletal muscle fibre
OTHER CAUSES :
ANTICIPATED FATIGUE
• the CNS might perceive fatigue prior to physiological fatigue
BODY FLUID BALANCE
• fluid loss decreases plasma volume which reduces blood pressure
• hence a reduction in blood flow to skin and muscles
• hence the heart has to work harder, body temperature rises, hence fatigue occurs
• hence fluid intake is important during endurance activities
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Unit 6 A.2.4
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
MUSCLE FATIGUE
FLUID INTAKE
• water loss of as little as 2% to 3% can reduce performance
• the graph shows how heart rate is affected by fluid intake during prolonged exercise
•
•
hence an isotonic sports
drink including glucose
and essential electrolytes
prevents dehydration
and supplements energy
and electrolytes lost
through sweating
•
or just take water
•
hypertonic sports drink
immediately after exercise
has finished
begins replenishment of
blood glucose,
glycogen store and
essential electrolytes
•
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Unit 6 A.2.5
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
EXCESS POST-EXERCISE OXYGEN CONSUMPTION (EPOC)
FACTORS CONTRIBUTING TO EPOC
elevated
hormonal levels
resynthesis of
muscle PC stores
factors affecting
EPOC
removal of lactic
acid
resaturation of
muscle myoglobin
with oxygen
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elevated HR and
breathing rate
elevated body
temperature
Unit 6 A.2.6
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
THE RECOVERY PROCESS
EXCESS POST-EXERCISE OXYGEN CONSUMPTION (EPOC)
• this is the excess O2 consumed following exercise
• needed to provide the energy needed to resynthesise ATP used
• and remove lactic acid created during previous exercise
• EPOC has two components :
– ALACTIC
– LACTIC
AIM OF RECOVERY PROCESS
• to replace ATP and
glycogen stores as soon as
possible
OXYGEN DEFICIT
• the difference between the
O2 required during
exercise and the O2 actually
consumed during the
activity
OXYGEN DEBT
• the graph shows the relationship between O2 consumption and
the time before, during and after exercise
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Unit 6 A.2.7
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
THE RECOVERY PROCESS
THE ALACTACID COMPONENT
• involves the conversion of ADP back into PC
and ATP
•
•
•
this is known as restoration of muscle
phosphagen
and is a very rapid process (120 seconds to
full restoration)
size 2 to 3.5 litres of O2
this is achieved via THREE MECHANISMS :
•
aerobic conversion of carbohydrates into CO2 and H2O to resynthesise ATP
from ADP and Pi
•
some of the ATP is immediately utilised to create PC using the coupled reaction :
ATP + C ---> ADP + PC
•
small amount of ATP is resynthesised via glycogen producing small amounts of
lactic acid
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Unit 6 A.2.8
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
THE RECOVERY PROCESS
IMPLICATIONS FOR INTERVAL TRAINING
• if there is only a short interval between bouts of exercise
• level of phosphagen stores gradually reduces
EFFECTS OF TRAINING ON THE ALACTACID COMPONENT
• increase ATP and PC stores in muscle cells
• improved ability to provide O2
• therefore increase in possible size of alactic component
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Unit 6 A.2.9
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
THE RECOVERY PROCESS
LACTACID OXYGEN RECOVERY
• high intensity exercise up to 60
seconds creates lactic acid
• oxygen is needed to remove this lactic
acid
• the process begins to restore muscle
and liver glycogen
RECOVERY
• the process is relatively slow
• full recovery takes up to 1 hour
• relatively large amounts of lactic
acid (15 to 20 times the resting value of
1 to 2 mmol litre-1) are produced during
high intensity exercise
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Unit 6 A.2.10
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
THE RECOVERY PROCESS
FATE OF THE LACTIC ACID
• oxidation into CO2 + H2O
65%
• conversion into glycogen
20%
then stored in muscle and
liver (Cori cycle)
• conversion into protein
10%
• conversion into glucose
5%
THE LACTATE SHUTTLE
• during the recovery process after intense execise
• a small proportion of the lactic acid produced is recycled back into
glucose in the muscle cell
• this is the reverse process to glycolysis
• requiring energy from ATP breakdown
BUFFERING
• A blood buffer is a chemical substance which resists abrupt changes in
hydrogen ion (H+) concentration
• example : when H+ concentration increases as a result of intense exercise
• H+ reacts with oxyhaemoglobin (buffer) to form haemoglobinic acid
• these ions are released when H+ concentration falls
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Unit 6 A.2.11
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
EFFECT OF COOL-DOWN ON LACTIC ACID REMOVAL
REMOVAL OF LACTIC ACID FOLLOWING EXERCISE
• cool-down continues to provide oxygen to skeletal muscle
• which therefore enhances oxidation of lactic acid
• and ensures that less lactic acid remains in tissue
• and there is less muscle soreness
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Unit 6 A.2.12
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
RECOVERY OF BODY STORES
RESTORATION OF MUSCLE GLYCOGEN STORES
• short duration high intensity exercise, restoration of glycogen takes up to 2
hours
• prolonged low intensity aerobic exercise, restoration can take days
•
•
•
a high carbohydrate diet speeds up the glycogen recovery process
there is a need for the athlete to restore stores as soon as possible after activity
example : a high CHO loaded drink immediately following exercise
MUSCLE MYOGLOBIN
• an iron protein molecule located in skeletal muscle (similar to haemoglobin)
• serves as a storage site for O2
• has a temporary but greater affinity for O2
• acts as a carrier of O2 from HbO2 (in blood) to mitochondria (in muscle cell)
• important in high intensity exercise
RESTORATION OF MYOGLOBIN
• myoglobin is reoxygenated within 2 minutes
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Unit 6 A.2.13
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
IMPLICATIONS FOR INTERVAL TRAINING OF LACTACID
RECOVERY
INTERVAL TRAINING
• when planning training sessions, rates of recovery must be take into account
• recovery between bouts of exercise is dependent on heart rate values
• as heart rate (HR) falls during recovery, its value is a measure of lactacid
recovery
• therefore repeating an exercise bout may not be possible until HR has fallen by
a certain amount
•
active recovery / cool-down speeds up removal of lactic acid
•
variance in intensity of workload in sessions doesn’t always stress the lactic
acid system
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Unit 6 A.2.14
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
FUEL FOR EXERCISE
A BALANCED DIET
• contains proportions of :
– carbohydrates, fats and proteins
– minerals, vitamins, water and roughage (fibre)
• needed to maintain good health
CARBOHYDRATE - 55%
• principal energy giver
FATS - 30%
• storage of energy
• another cource of energy
• carrier of fat soluble vitamins
PROTEIN - 15%
• essential for growth, body building and repair
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Unit 6 A.2.15
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
STORAGE AND RELEASE OF FOOD FUELS
CARBOHYDRATES
• glucose is absorbed in the small intestine
GLUCOSE
• is utilised as fuel in the liver
• then stored as liver glycogen
• transported as glucose in the blood to other tissues (for example skeletal
muscle)
• used as an immediate source of energy
• or converted and stored as muscle glycogen
FATS
• absorbed as fatty acids or glycerol in the small intestine
FATTY ACIDS
• utilised as fuel in the liver
• stored as triglycerides in adipose tissue or skeletal muscle
• recalled from fat deposits to the liver
• converted to glucose (this is a slow process)
• enters the Kreb’s cycle in aerobic respiration
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Unit 6 A.2.16
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
FOOD FUEL USAGE DURING EXERCISE
DURING HIGH INTENSITY EXERCISE
AT REST
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Unit 6 A.2.17
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
EXERCISE AND FOOD FUEL USAGE
FOOD FUEL USAGE
• dependent on exercise intensity and duration
AT REST
• ATP utilisation slow
• a mixture of fats and carbohydrates
INTENSITY HIGH / DURATION SHORT
• rapid and immediate increase in ATP usage
• PC provides ATP resynthesis
• muscle and liver glycogen stores used
• lactic acid produced
INTENSITY LOW / DURATION LONG
• oxidation of a mixture of carbohydrates and fats
• the longer the exercise the bigger the proportion of ATP regenerated from
fats
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Unit 6 A.2.18
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
FOOD FUEL UTILISATION DURING EXERCISE
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Unit 6 A.2.19
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
FOOD FUEL USAGE FOR AEROBIC ACTIVITY
FOOD FUEL USAGE
• this depends on :
– EXERCISE INTENSITY
– EXERCISE DURATION
AT REST
• ATP utilisation is slow
• a mixture of fats and carbohydrates is
used to resynthesise ATP
FOR LOW INTENSITY LONG DURATION
AEROBIC ACTIVITY
• usage of a variety of fuels
• but mainly the oxidation of a mixture of
CHO and fats
• the longer the exercise the bigger the
proportion of ATP resynthesis provided
by fats
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Unit 6 A.2.20
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
FOOD FUEL USAGE FOR AEROBIC ACTIVITY
SOURCES OF FUELS
• main source of CHO for muscular energy during exercise is glucose
• derived from stored muscle and liver glycogen
• lack of CHO fuel is the limiting factor for aerobic endurance performance
•
•
•
•
•
main source of fat for muscular energy during exercise is free fatty acids
(FFA)
derived from triglycerides stored as adipose tissue under the skin and in
muscle tissue
triglycerides break
down into FFA for
entry into the
aerobic energy
system
proteins become a
significant source of
energy only in
extreme conditions
when CHO and fats
are depleted
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Unit 6 A.2.21
Fatigue and the Recovery Process
Edexcel A Level Physical Education A 9536
NUTRITION AND EXERCISE
CARBOLOADING
• aims to raise muscle glycogen stores above their normal resting levels
• prior to endurance competitions with over 90 minutes continuous activity
• suitable for activities with low anaerobic and high aerobic components
• based on :
• depletion - prolonged exercise to reduce levels of liver and muscle
glycogen stores - at least seven days before event
• repletion - a high CHO diet in the period (three to four days) before
activity
• combined with light exercise or rest
• also suitable for activities lasting 15 - 20 minutes
• with a two day high CHO diet beforehand
Carbohydrate loading (new technique after Williams 1998)
Endurance
taper
taper
taper
taper
taper
taper
training
training training training training training training
day 1
day 2
normal
diet
moderate----------------------
CHO diet
•
day 3
day 4
day 5
day 6
day 7
race
high ----------------------------------
CHO diet
this technique omits the glycogen depletion phase associated with earlier methods
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Unit 6 A.2.22
Fatigue and the Recovery Process
Edexcel A Level Physical Education A 9536
NUTRITION AND EXERCISE
CARBOLOADING
THE IMPORTANCE OF HIGH GLYCOGEN CONTENT IN MUSCLE BEFORE A
MARATHON RACE
• the graph shows
that a runner’s time
would increase by
more than 10
minutes in a 2 hour
run
• if muscle glycogen
is at 50% of its
maximum possible
• the effect of
reduced muscle
glycogen begins to
be felt at the 1 hour
mark
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Unit 6 A.2.23
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
NUTRITION AND EXERCISE
DIETARY MANIPULATION
PRECOMPETITION NUTRITION
• fluids for hydration
• light complex CHO such as pasta / wholemeal bread at least 3
hours before activity
• fruit (banana) contains complex CHO and small amounts of
glucose
• effect is to provide the slow release of blood glucose
• and reduce hunger sensations
POST COMPETITION / TRAINING NUTRITION
• hypertonic sports drink immediately after exercise has finished
• begins replenishment of blood glucose and glycogen store
• a high CHO meal within 15 minutes of exercise ending
continues glycogen replenishment
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Unit 6 A.2.24
Edexcel A Level Physical Education A 9536
Energy Sources
WATER BALANCE
WATER BALANCE
• excessive loss of fluid impairs
performance
• as blood plasma volume
decreases
• and body temperature rises
• extra strain is placed on the
heart, lungs and circulatory
system
• which means that the heart has
to work harder to pump blood
around the body
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Unit 6 A.2.25
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
NUTRITION AND EXERCISE
FLUID INTAKE DURING OR IN BETWEEN EXERCISE
• water loss of as little as 2% to 3% can reduce performance
• the graph shows how heart rate is affected by fluid intake during prolonged exercise
•
•
•
hence an isotonic sports
drink including very
diluted sodium and
glucose content
prevents dehydration
and supplements energy
reserves
or just take water
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Unit 6 A.2.26
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
NUTRITION AND EXERCISE
DIETARY MANIPULATION
• the following graph shows the influence of dietary carbohydrate on muscle
glycogen stores
• repeated daily exercise of 2 hours is followed by a either a high CHO or low
CHO diet
• on a low CHO diet, muscle fatigue would be considerably greater
accumulating over a period of days
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Unit 6 A.2.27
Edexcel A Level Physical Education A 9536
Fatigue and the Recovery Process
FOOD FUEL UTILISATION DURING ANAEROBIC ACTIVITY
ENERGY SYSTEMS
HIGH INTENSITY MAXIMAL WORK FOR LESS THAN 8 seconds
• the PC alactic energy system provides the majority of ATP resynthesis for this
period
• food fuels used are direct use of PC stored in the muscle cell
• then those involved in the oxygen recovery phase after exercise
• which is an aerobic process, and inputs food fuel from mostly CHO and some fats
HIGH INTENSITY WORK FOR UP TO 60 seconds (STRENGTH ENDURANCE)
• the lactic acid energy system provides the bulk of ATP for this period
• food fuels used directly are muscle glycogen via glycolysis
• then those involved in the oxygen recovery phase after exercise
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Unit 6 A.2.28
Edexcel A Level Physical Education A 9536
Physiological Adaptations
RESPONSE TO EXERCISE and TRAINING
on the ENERGY SYSTEMS - and your IPP
YOUR PEP and TRAINING RESULTS
YOUR PEP
• students are required to plan, perform, report and evaluate their physical
activity
• which will form the basis of their personal exercise plan (PEP)
THE RESULTS AND YOUR IPP
• the PEP and the outcomes of the physical activity are to be recorded in
the student’s individual performance portfolio (IPP)
• students should analyse their performance in terms of :
– explaining short-term effects of exercise in terms of energy systems
– explaining physiological adaptations observed in their own activity
– explain how these adaptations enhance performance
•
•
this is in addition to the recording of the results of fitness tests integrated
into unit 3
which could be a means of assessing whether adaptations have occurred
or not
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Unit 6 A.2.29