13.Effects of Exercise
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Transcript of 13.Effects of Exercise
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Boardworks Ltd 20061 of 30
The Effects of Exercise
Boardworks Ltd 20061 of 30
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For more detailed instructions, see the Gett ing Startedpresentation.
KS4 Physical
Education
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Learning objectives
What we will learn in this presentation:
Lea
rningo
bjective
s
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The immediate effects of exercise on therespiratory system
The immediate effects of exercise on the
circulatory system
How levels of lactic acid, water and heat are
affected by exercise
How the body recovers from exercise
Recovery ratesThe long term effects of exercise on the heart,
lungs, skeleton and muscles
How different components of fitness can be
tested.
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The immediate effects of exercise
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Immediate effects on the respiratory system
Exercise causes the muscles to use more oxygen.
This means that the lungsmust work harderand fastertokeep the body supplied with oxygen and also to exhale the
carbon dioxide that is produced. This is why exercise
makes you out-of-breath.
Breathing rate increases from around 18 breaths perminute to up to 80!
The amount of air inhaled and exhaled in each breath also
increases from around 0.5 litres to up to 4.5 litres.
Duringaerobic exercise, the lungs are able to workfast enough to supply the muscles with oxygen.
During anaerobic exercise, the lungs cant supply
enough oxygen. Once the exercise is over,
breathing remains fast to repay the oxygen debt.
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Immediate effects on the circulatory system
During exercise, the circulatory systems most important
function is transportation.The heart and blood vessels work to transport the oxygen
from the lungs to the muscles where it is needed. Glucose
and other substances needed by the muscles are
transported in the blood too.The by-products of respiration, including carbon dioxide
and lactic acid, are also carried away from the muscles.
If these by-products build up in the muscles,
they can cause them to stop working.
glucose + oxygen energycarbon
diox ide+ + water
g lucose energy + lact ic acid
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Immediate effects on the circulatory system
Write a paragraph explaining how the roles of the
heart and lungs in supporting exercise are connected.
In response to exercise, the heart beats not only faster,
but stronger.Heart rateincreases from around 70 bpm to up to 200 bpm.
Stroke volume(the volume of blood pumped per beat)
increases from around 50 ml to around 120 ml. In highly
trained athletes, stroke volume can reach 200 ml.The arteriesrespond to the bodys increased demands by
widening slightly to allow more blood to pass through them.
Blood is also divertedaway from systems that are not
involved in the activity, for example, the digestive system.
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The immediate effects: lactic acid
Lactic acidis produced during anaerobic respiration.
This happens when there is not enough oxygen fornormal aerobic respiration to take place.
Lactic acid is a mild toxin. It is responsible
for the pain you feel in your muscles when
they get tired.
When too much of it builds up in a muscle,it can prevent the muscle contracting. At
this point, the performers muscles will
crampand they will be forced to stop.
glucose energy + lact ic acid
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The immediate effects: heat loss
The body has twomain ways of getting rid of the extra
heatproduced by muscles during exercise.1. Vasodilation
The capillariesclose to the surface of the
skin dilate, allowing more blood to flow into
them. Because the blood is closer to theskin, more heat is lost to the environment.
2. Sweating
Sweat glands in the skin excretesweata mixture of water, salts and
urea. As the sweat evaporates, it
takes heat away with it.
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The immediate effects: water loss
When you sweat, water is lostfrom the
body. Water is vital to maintaining properbody functions.
The body produces less urineto
compensate, but during prolonged exercise
or in hot weather, this is often not enough.Extra water must also be consumed.
The body does not only lose waterit also loses important
saltscalled electrolytes. These are necessary in many
areas of the body, including the nervous system.
Salts can be replaced during exercise by drinking isotonic
drinks, or eating foods rich in these minerals.
Severe salt depletion can lead to cramps,
fainting and, in extreme cases, death.
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Immediate effects of exercise
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Recovery rates
Muscles
Your recovery rateis how quickly your body returns to
normal following a period of exercise.Recovery rate is a good indicator of fitness. The quicker
you recover, the fitter you are.
As you recover from exercise, changes happen in the
following areas:
Heart rate
Lactic acid levels in the blood
Glycogen stores
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Heart rate
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Lactic acid
Lactic acid is produced when the body cannot supply the
muscles with enough oxygen.In this situation, the body builds up an oxygen debtthis is
repaid by continuing to breathe heavily for a period after
exercise ceases.
The rate at which lactic acidis removed can be increased
by performing a cool-down
at the end of a session.
As more oxygen becomesavailable, it reacts with the
lactic acid to form
harmless substances.
Resting
recovery
Active
recovery
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Glycogen stores
Food is converted to
glycogenby the body andstored in the muscles and
liver as an energy reserve.
As you exercise, muscle
glycogen is used up and ittakes some time to replace.
After prolonged exercise, for
example a marathon, it can
take more than 48 hoursfor
the glycogen stores to fully
recover.
You can increase the rate at which glycogen is
replenished by eating a carbohydrate rich diet.
This graph shows glycogen levels
during and after a marathon.
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Muscles
Strenuous exercise can cause slight
damageto the muscle fibres.It is actually through this process of damage
and repair that muscles become stronger.
As you would expect, your body needs time
to repair the damage done to musclesduring exercise or training.
After exercise, we sometimes experience
stiffnessor soreness for a period of time
until our muscles have fully recovered.This soreness can also be caused by lactic
acid remaining in the muscles.
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Recovery time
When you plan your training,
ensure that you allow yourbody enough time to recover
between training sessions.
It you train hard every day,
try and alternatebetweenheavy sessions and light
sessions to aid recovery
Always ensure that you have
the appropriate rest periodsor you run the risk of injury
through overtraining.
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Recovery
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Testing recoverythe Harvard Step Test
To undertake this test, you will require:
a gym bench (approx 45 cm or 18 inches high)Ensure that the bench is firmly fixed and will not slip.
The Harvard Step Testis a fitness test that uses recovery
rate to help assess a performers aerobic endurance.
a stop watch
someone to help youkeep the required pace.
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ProcedureHarvard Step Test
Before you start, record your resting heart rate.
Step up onto the bench once every two seconds for fiveminutes (150 steps in total).
At the end of the five minute period of stepping, rest for one
minute and then check and record the number of times
your heart beats in the next 30 seconds.
Two minutes after you have finished exercising, count your
heart beats again for 30 seconds.
Three minutes after you have finished exercising, count
your heart beats again for 30 seconds.
You can then use these three
figures to work out your score.
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RecordingHarvard Step Test
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The long term effect of exercise
As you would expect, training causes the body to adapt
and grow stronger.
The following areas are particularly affected:
the heart
the lungs
the skeleton
the muscles.
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The long term effect of exercisethe heart
Aerobic exercise strengthens the heart.
The heart becomes bigger.
The walls become thickerand
stronger.
The stroke volumeincreases.
Your resting heart rategets sloweras you get fitter, because
the heart needs fewer beats to pump blood round the body.
Training also results in new capillariesgrowing to improve
the supply of blood to the muscles.
The result is that the heart
becomes a more efficientpump.
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The long term effect of exercisethe lungs
Training makes the lungsmore effective
at supplying the body with oxygen.New capillaries
grow around the
alveoli, making
gas exchangemore efficient.
The musclesinvolved in
breathing in and out become
stronger and can work for longer.Vital capacity(the maximum
amount of air that can be inhaled
in one breath) increases.
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The long term effect of exercisethe skeleton
Exercise has been shown to increase
bone densityand strength.Stronger, denser bones are better
at carrying weight and more
resistant to injury.
The increase in bone density isspecificto the activitywalking
will strengthen your leg bones,
but not your arm bones.
Both aerobic exercise and weighttraining are effective in increasing
bone strength, but the activity must
be weight-bearing.
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The long term effect of exercisethe muscles
Training obviously has a large effect on the muscles.
The other effects will depend on the type of training.
Weight and power training
increases the strength of muscles.
The number of fast twitch fibres
increase. Muscles increase in size.
New capillariesgrow in and around themuscles to supply them with blood.
Endurance trainingmakesmuscles able to work for
longer. The number of slow
twitch fibres increase. EMPICS Ltd
EMPICS Ltd
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The effects of exercise
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Testing cardiovascular fitness
The best way of measuring cardiovascular fitness is to
calculate a performers VO2max.this measures themaximum amount of oxygen the body can take in.
However, calculating VO2max. requires very
specialized equipment.
The easiest test is the 12 minute run. Performers simply
run for 12 minutes and the distance covered is recorded.
An alternative is the bleep test.Performers have to do 20 metre shuttle
runs, keeping pace with a series of
recorded bleeps which gradually get
faster. The point at which the
performer has to drop out is recorded.
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Testing speed, flexibility and balance
Speedis easy to test. Simply record how fast a
performer can sprint a short distance. 100 metreand 60 metre distances are often used.
Flexibilitycan be tested by
measuring a performers range of
movement. A common test forflexibility is the sit and reach test.
Balancecan be tested using the stork stand test. The
performer stands on one leg, with their free foot on their
standing knee. How long they can hold the position for is timed.
How far the performer can reach relative to their feet is
measured on a ruler.
T i ili d l d
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Testing agility and muscular endurance
Agilitycan be tested by setting up
an agility runand timing how long ittakes for a performer to complete it.
When retestingperformers to
measure improvement, you must
take care that the agility run is set
up exactly the same as before.
Muscular endurancecan be tested
easily by seeing how many times a
performer can repeat a movementrequiring strength. Sit-upsand
press-ups are often used.
E t l ti
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Exam-style questions
1. Describe the changes that occur in the functioning of the
cardio-respiratorysystem during moderate, sustainedexercise.
2. List twoways in which each of the following structures
are affected by training.
a) The lungsb) The skeleton
3. Neena has just completed a 10 km fun run.
a) Explain how the run will have affected the levels of
lactic acidand glycogenin her body.
b) Suggest twothings that she could do to aid her
recovery.