Edexcel A Level Physical Education A 9536 Next Previous Unit 6 A.2.1 Edexcel Examinations A Level Physical Education A 9536 Unit 6 : Section A part 2 Scientific

Unit 6 A.2.1

Edexcel A Level Physical Education A 9536

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Edexcel ExaminationsA Level Physical Education

A 9536

Unit 6 : Section Apart 2

Scientific Principles of Exercise and Performance

Unit 6 A.2.2


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INDEX18 - EXERCISE AND FOOD FUEL USAGE FOOD FUEL USAGE AT REST AND DIFFERNET

INTENSITY AND DURATION19 - FOOD FUEL UTILISATION DURING EXERCISE20 - FOOD FUEL USAGE FOR AEROBIC ACTIVITY FOOD FUEL USAGE / EXERCISE INTENSITY /

DURATION21 - FOOD FUEL USAGE FOR AEROBIC ACTIVITY SOURCES OF FUELS22 - NUTRITION AND EXERCISE - CARBOLOADING23 - NUTRITION AND EXERCISE - CARBOLOADING IMPORTANCE OF HIGH GLYCOGEN CONTENT24 - NUTRITION AND EXERCISE PRE / POST / DURING COMPETITION NUTRITION25 - WATER BALANCE26 - NUTRITION AND EXERCISE - FLUID INTAKE27 - NUTRITION AND EXERCISE - DIETARY MANIPULATION28 - FOOD FUEL UTILISATION DURING ANAEROBIC

ACTIVITYHIGH INTENSITY 8 seconds / 60 seconds

29 - RESPONSE TO EXERCISE and TRAINING on the ENERGY SYSTEMS - and your IPP

Index

3 - MUSCLE FATIGUEDEPLETION OF ENERGY STORES / FIBRE TYPE / METABOLIC ACCUMULATION

4 - MUSCLE FATIGUEINTERRUPTION OF NEUROMUSCULAR EVENTSANTICIPATED FATIGUE / BODY FLUID BALANCE

5 - MUSCLE FATIGUE - FLUID INTAKE6 - EXCESS POST-EXERCISE OXYGEN CONSUMPTION (EPOC)

FACTORS CONTRIBUTING TO EPOC7 - THE RECOVERY PROCESS

EPOC / AIM OF RECOVERY PROCESSOXYGEN DEFICIT / DEBT

8 - THE RECOVERY PROCESSTHE ALACTACID COMPONENT

9 - THE RECOVERY PROCESSIMPLICATIONS FOR INTERVAL TRAINING / EFFECTS OF TRAINING

10 - THE RECOVERY PROCESSLACTACID OXYGEN RECOVERY / RECOVERY

11 - THE RECOVERY PROCESS - FATE OF LACTIC ACID / THE LACTATE SHUTTLE /

BUFFERING12 - EFFECT OF COOL-DOWN ON LACTIC ACID REMOVAL

REMOVAL OF LACTIC ACID FOLLOWING EXERCISE13 - RECOVERY OF BODY STORES

RESTORATION OF MUSCLE GLYCOGEN / MYGLOBIN STORES

14 - IMPLICATIONS FOR INTERVAL TRAINING OF LACTACID RECOVERY

15 - FUEL FOR EXERCISEA BALANCED DIET / CARBOHYDRATE / FATS / PROTEIN

16 - STORAGE AND RELEASE OF FOOD FUELSCARBOHYDRATES / GLUCOSE / FATS / FATTY ACIDS

17 - FOOD FUEL USAGE DURING EXERCISEDURING HIGH INTENSITY EXERCISE / AT REST

Unit 6 A.2.3


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MUSCLE FATIGUEFatigue and the Recovery Process

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

Unit 6 A.2.4


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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 fatigueBODY 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

Unit 6 A.2.5


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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

Unit 6 A.2.6


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EXCESS POST-EXERCISE OXYGEN CONSUMPTION (EPOC)

FACTORS CONTRIBUTING TO EPOC

Fatigue and the Recovery Process

factors aff ectingEPO C

elevatedhormonal levels

elevated HR andbreathing rate

resynthesis ofmuscle PC stores

removal of lacticacid

elevated bodytemperature

resaturation ofmuscle myoglobin

w ith oxygen

Unit 6 A.2.7


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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

Unit 6 A.2.8


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THE RECOVERY PROCESSTHE 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

Unit 6 A.2.9


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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

Unit 6 A.2.10


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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


Unit 6 A.2.11


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THE RECOVERY PROCESSFatigue and the Recovery Process

FATE OF THE LACTIC ACID

• oxidation into CO2 + H2O 65%

• conversion into glycogen 20%then stored in muscle andliver (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 breakdownBUFFERING• 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

Unit 6 A.2.12


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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


Unit 6 A.2.13


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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 exerciseRESTORATION OF MYOGLOBIN• myoglobin is reoxygenated within 2 minutes


Unit 6 A.2.14


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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


Unit 6 A.2.15


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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


Unit 6 A.2.16


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STORAGE AND RELEASE OF FOOD FUELSCARBOHYDRATES• 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


Unit 6 A.2.17


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FOOD FUEL USAGE DURING EXERCISEDURING HIGH INTENSITY EXERCISE


AT REST

Unit 6 A.2.18


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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


Unit 6 A.2.19


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FOOD FUEL UTILISATION DURING EXERCISEFatigue and the Recovery Process

Unit 6 A.2.20


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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


Unit 6 A.2.21


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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


Unit 6 A.2.22


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NUTRITION AND EXERCISEFatigue and the Recovery Process

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 tapertraining training training training trainingtraining trainingday 1 day 2 day 3 day 4 day 5 day 6 day 7 race normal moderate---------------------- high ---------------------------------- diet

CHO diet CHO diet

• this technique omits the glycogen depletion phase associated with earlier methods

Unit 6 A.2.23


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CARBOLOADINGTHE 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

Unit 6 A.2.24


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DIETARY MANIPULATIONPRECOMPETITION 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

Unit 6 A.2.25


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WATER BALANCE

Energy Sources

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

Unit 6 A.2.26


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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

Unit 6 A.2.27


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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

Unit 6 A.2.28


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FOOD FUEL UTILISATION DURING ANAEROBIC ACTIVITY


ENERGY SYSTEMSHIGH 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

Unit 6 A.2.29


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RESPONSE TO EXERCISE and TRAINING on the ENERGY SYSTEMS - and your IPP

Physiological Adaptations

YOUR PEP and TRAINING RESULTSYOUR 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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Edexcel A Level Physical Education A 9536 Next Previous Unit 6 A.2.1 Edexcel Examinations A Level Physical Education A 9536 Unit 6 : Section A part 2 Scientific