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The Effects of Exercise
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KS4 Physical Education
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Learning objectives
What we will learn in this presentation:Le
arni
ng o
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tives
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The immediate effects of exercise on the respiratory systemThe immediate effects of exercise on the circulatory systemHow levels of lactic acid, water and heat are affected by exerciseHow the body recovers from exerciseRecovery ratesThe long term effects of exercise on the heart, lungs, skeleton and musclesHow 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 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’.
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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 energy carbon dioxide+ + water
glucose energy + lactic 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 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.
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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
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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. SweatingSweat glands in the skin excretesweat – a 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 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.
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Immediate effects of exercise
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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
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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 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-downat the end of a session.
As more oxygen becomes available, it reacts with the lactic acid to form harmless substances.
Resting recovery
Active recovery
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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.
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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.
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Recovery time
When you plan your training, ensure that you allow your body enough time to recoverbetween 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.
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Recovery
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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.
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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.
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Recording – Harvard 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 heartthe lungs
the skeletonthe muscles.
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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.
long term effect of exercise – the lungs
Training makes the lungs more effective at supplying the body with oxygen.
New capillariesgrow 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
ong term effect of exercise – the skeleton
rcise has been shown to increase ne density and strength.onger, denser bones are better arrying weight and more stant to injury.increase in bone density is
cific to the activity – walking strengthen your leg bones, not your arm bones.h aerobic exercise and weight ning are effective in increasing e strength, but the activity must
i ht b i
ong term effect of exercise – the muscles
ning obviously has a large effect on the muscles.
other effects will depend on the type of training.
Weight and power trainingincreases 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
PICS Ltd
effects of exercise
ng cardiovascular fitness
best way of measuring cardiovascular fitness is to culate a performer’s VO2 max. – this measures the ximum amount of oxygen the body can take in.wever, calculating VO2 max. requires very cialized equipment.
easiest test is the 12 minute run. Performers simply f 12 i t d th di t d i d d
alternative is the bleep test. formers have to do 20 metre shuttle s, keeping pace with a series of orded bleeps which gradually get er. The point at which the former has to drop out is recorded.
ng speed, flexibility and balance
eed is easy to test. Simply record how fast a former can sprint a short distance. 100 metre 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.
ance can be tested using the stork stand test. The former stands on one leg, with their free foot on their nding knee How long they can hold the position for is timed
w far the performer can reach relative to their feet is asured on a ruler.
ng agility and muscular endurance
lity can be tested by setting up agility run and timing how long it es for a performer to complete it.en retesting performers to asure improvement, you must e care that the agility run is set 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.
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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 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 acid and glycogen in her body.b) Suggest two things that she could do to aid her
recovery.
