13.effects of exercise

8/10/2019 13.Effects of Exercise

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Boardworks Ltd 20061 of 30

The Effects of Exercise


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KS4 Physical

Education


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Learning objectives

What we will learn in this presentation:

Lea

rningo

bjective

s


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.



Immediate effects of exercise



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



Heart rate



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



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.



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.



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.



Recovery



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.



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.



RecordingHarvard Step Test



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.



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.



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.



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.



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



The effects of exercise



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.

13.effects of exercise

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