KS4 Physical Education - St Christopher's Church of .... effects of exercise (o2... · Procedure...

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The Effects of Exercise


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KS4 Physical

Education


Learning objectives

What we will learn in this presentation:

Le

arn

ing

ob

jecti

ves


The immediate effects of exercise on the

respiratory 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 rates

The long term effects of exercise on the heart,

lungs, skeleton and muscles

How different components of fitness can be

tested.


The immediate effects of exercise


Immediate effects on the respiratory system

Exercise causes the muscles to use more oxygen.

This means that the lungs must work harder and faster to

keep 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 per

minute 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.

During aerobic exercise, the lungs are able to work

fast enough to supply the muscles with oxygen.

During anaerobic exercise, the lungs can’t supply

enough oxygen. Once the exercise is over,

breathing remains fast to repay the ‘oxygen debt’.


Immediate effects on the circulatory system

During exercise, the circulatory system’s 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

dioxide+ + water

glucose energy + lactic acid


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 rate increases 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 arteries respond to the body’s increased demands by

widening slightly to allow more blood to pass through them.

Blood is also diverted away from systems that are not

involved in the activity, for example, the digestive system.


The immediate effects: lactic acid

Lactic acid is produced during anaerobic respiration.

This happens when there is not enough oxygen for

normal 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 performer’s muscles will

cramp and they will be forced to stop.

glucose energy + lactic acid


The immediate effects: heat loss

The body has two main ways of getting rid of the extra

heat produced by muscles during exercise.

1. Vasodilation

The capillaries close to the surface of the

skin dilate, allowing more blood to flow into

them. Because the blood is closer to the

skin, more heat is lost to the environment.

2. Sweating

Sweat glands in the skin excrete

sweat – a mixture of water, salts and

urea. As the sweat evaporates, it

takes heat away with it.


The immediate effects: water loss

When you sweat, water is lost from the

body. Water is vital to maintaining proper

body functions.

The body produces less urine to

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 water – it also loses important

salts called 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 rate is 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 debt – this is

repaid by continuing to breathe heavily for a period after

exercise ceases.

The rate at which lactic acid

is removed can be increased

by performing a cool-down

at the end of a session.

As more oxygen becomes

available, it reacts with the

lactic acid to form

harmless substances.

Resting

recovery

Active

recovery


Glycogen stores

Food is converted to

glycogen by the body and

stored in the muscles and

liver as an energy reserve.

As you exercise, muscle

glycogen is used up and it

takes some time to replace.

After prolonged exercise, for

example a marathon, it can

take more than 48 hours for

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

damage to 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 muscles

during exercise or training.

After exercise, we sometimes experience

stiffness or 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 your

body enough time to recover

between training sessions.

It you train hard every day,

try and alternate between

heavy sessions and light

sessions to aid recovery

Always ensure that you have

the appropriate rest periods

or you run the risk of injury

through overtraining.


Recovery


Testing recovery – the 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 Test is a fitness test that uses recovery

rate to help assess a performer’s aerobic endurance.

a stop watch

someone to help you

keep the required pace.


Procedure – Harvard Step Test

Before you start, record your resting heart rate.

Step up onto the bench once every two seconds for five

minutes (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.


Recording – Harvard 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 exercise – the heart

Aerobic exercise strengthens the heart.

The heart becomes bigger.

The walls become thicker and

stronger.

The stroke volume increases.

Your resting heart rate gets slower as you get fitter, because

the heart needs fewer beats to pump blood round the body.

Training also results in new capillaries growing to improve

the supply of blood to the muscles.

The result is that the heart

becomes a more efficient pump.


The long term effect of exercise – the lungs

Training makes the lungs more effective

at supplying the body with oxygen.

New capillaries

grow around the

alveoli, making

gas exchange

more efficient.

The muscles involved 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 exercise – the skeleton

Exercise has been shown to increase

bone density and strength.

Stronger, denser bones are better

at carrying weight and more

resistant to injury.

The increase in bone density is

specific to the activity – walking

will strengthen your leg bones,

but not your arm bones.

Both aerobic exercise and weight

training are effective in increasing

bone strength, but the activity must

be weight-bearing.


The long term effect of exercise – the 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 capillaries grow in and around the

muscles to supply them with blood.

Endurance training makes

muscles 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 performer’s VO2 max. – this measures the

maximum amount of oxygen the body can take in.

However, calculating VO2 max. 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.


Testing speed, flexibility and balance

Speed is easy to test. Simply record how fast a

performer can sprint a short distance. 100 metre

and 60 metre distances are often used.

Flexibility can be tested by

measuring a performer’s range of

movement. A common test for

flexibility is the sit and reach test.

Balance can 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.


Testing agility and muscular endurance

Agility can be tested by setting up

an agility run and timing how long it

takes for a performer to complete it.

When retesting performers to

measure improvement, you must

take care that the agility run is set

up exactly the same as before.

Muscular endurance can be tested

easily by seeing how many times a

performer can repeat a movement

requiring strength. Sit-ups and

press-ups are often used.


Exam-style questions

1. Describe the changes that occur in the functioning of the

cardio-respiratory system during moderate, sustained

exercise.

2. List two ways in which each of the following structures

are affected by training.

a) The lungs

b) The skeleton

3. Neena has just completed a 10 km fun run.

a) Explain how the run will have affected the levels of

lactic acid and glycogen in her body.

b) Suggest two things that she could do to aid her

recovery.

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