Investigate the effect of exercise on the breathing rate or pulse rate of a human

INVESTIGATE THE EFFECT OF EXERCISE ON THE PULSE RATE OF A HUMAN

Do not attempt this activity if you have a health problem or if you are recovering from an illness

Materials/Equipment

Procedure

1. Familiarise yourself with all procedures before starting.
2. Sit down comfortably on a chair. Take 5 minutes to settle. Locate your pulse. If, at this point, you are using a pulse monitor, follow the manufacturer's instructions.
3. Count the number of pulses per minute and record.
4. Repeat twice and calculate the average number of pulses per minute and record. This is called the resting heart rate.
5. Stand up. Immediately measure your pulse rate and record.
6. Walk gently for 5 minutes. Immediately measure the pulse rate and record.
7. Walk briskly for 5 minutes. Immediately measure the pulse rate and record.
8. Run for 5 minutes. Immediately measure the pulse rate and record.
9. Compare the pulse rates after the different levels of exercise.
10. Replicate the investigation or cross reference your results with other groups.
11. A bar chart of the results should be drawn.

Result

Conclusion/Comment

To locate and measure your pulse
The most common place for you to feel a pulse is on your wrist. The pulse on your wrist is called a radial pulse because you measure the pulse near a bone called the radius. You can feel your radial pulse on either wrist, about an inch below your thumb.

If you do not use a pulse monitor, it is usually not possible to measure your pulse rate accurately while participating in most activities. However, an estimate of your exercise pulse rate can be obtained if your pulse rate is measured immediately after exercising. If you do not start counting within 10 seconds after stopping the exercise, the result is likely to be inaccurate.

With the palm of one hand facing upwards, hold the index and middle fingers of the other hand together and press lightly on the pulse site as in the diagram. You should feel an indented area. You may need to change the position of your fingers in order to feel your pulse really well.

Count the number of pulses in 10 seconds and multiply this value by 6 to convert it to beats/min. Do not count for a longer time because your heart rate begins to slow down as soon as you stop exercising. The fitter you are, the quicker your heart rate will decrease after exercise.

SKILL ATTAINMENT

Following instructions
Familiarise yourself with all procedures before starting
Follow instructions step by step
Listen to the teacher's instructions

Correct manipulation of apparatus
Use the timer
Attach the pulse monitor (if in use) to the body

Observation
Find a pulse
Observe changes in the pulse rate
Observe the effect of exercise on the pulse rate

Recording
Write up the procedure
Record the average resting pulse rate
Record the pulse rate after standing
Record the pulse rate after gentle walking
Record the pulse rate after brisk walking
Record the pulse rate after running
Draw a bar chart

Interpretation
Draw reasonable conclusions from your observations and results

Application
Become aware of any other application(s) of what you learned in this activity

Organisation
Exercise caution for your personal safety and for the safety of others
Work in an organised and efficient manner
Work as part of a group or team
Clean up after the practical activity

INVESTIGATE THE EFFECT OF EXERCISE ON THE BREATHING RATE OF A HUMAN

Do not attempt this activity if you have a health problem or if you are recovering from an illness

Materials/Equipment

Procedure

1. Familiarise yourself with all procedures before starting.
2. Sit down comfortably on a chair. Take 5 minutes to settle.
3. Count the number of breaths per minute and record.
4. Repeat step 4 twice and calculate the average. This is the resting breathing rate.
5. Stand up. Immediately measure the breathing rate and record.
6. Walk gently for 5 minutes. Immediately measure the breathing rate and record.
7. Walk briskly for 5 minutes. Immediately measure the breathing rate and record.
8. Run for 5 minutes. Immediately measure the breathing rate and record.
9. Compare the breathing rates after the different levels of exercise.
10. A bar chart of the results should be drawn.

Result

Conclusion/Comment

SKILL ATTAINMENT

Following instructions
Familiarise yourself with all procedures before starting
Follow instructions step by step
Listen to the teacher's instructions

Correct manipulation of apparatus
Use the timer

Observation
Observe changes in breathing
Observe the effect of exercise on the breathing rate

Recording
Write up the procedure
Record the average resting breathing rate
Record the breathing rate after standing
Record the breathing rate after gentle walking
Record the breathing rate after brisk walking
Record the breathing rate after running
Draw a bar chart

Interpretation
Draw reasonable conclusions from your observations and results

Application
Become aware of any other application(s) of what you learned in this activity

Organisation
Exercise caution for your personal safety and for the safety of others
Work in an organised and efficient manner
Work as part of a group or team
Clean up after the practical activity

Background information

It is important to remember that your heart rate varies depending on a number of different factors such as age, sex and exercise. It also depends on when it is measured and what you were doing immediately before measuring it. Allowing for this, the heart rates listed are considered to be average. Adults have a heart rate of 60 ­ 90 bpm (beats per minute) while resting. In the first year of life, the average heart rate is 120 ­ 160 bpm, and by the age of l2, it has usually fallen to 70 ­ 80 bpm. A child's heart rate continues to fall as he or she reaches adulthood.

Vigorous exercise accelerates heart rate in two ways: (i) Increased carbon dioxide production, due to respiration in muscle cells, causes a decrease in blood pH. This change in pH is detected by chemoreceptors in the walls of various blood vessels such as the aorta, carotid artery and vena cava. Impulses are sent from these receptors to the cardiovascular centre of the medulla oblongata, which also possesses receptors. Impulses are sent from the medulla oblongata, through the sympathetic nervous system, to the sino-atrial node (pacemaker) where the production of noradrenaline by the accelerator nerve brings about an increase in heart rate. (ii) As muscular activity increases, more blood is driven back to the right atrium. The atrium becomes distended with blood, thus stimulating stretch receptors in its wall. The stretching of the heart wall makes the heart pump more blood into the circulation.

The fastest heart rate that you can reach is known as the maximal heart rate. It is highest in childhood and gets lower with age. The maximal heart rate of a 20 year old when exercising is around 200 bpm, whereas a 60 year old has a maximal heart rate of around 160 bpm. To work out your maximal heart rate you need to do a simple calculation. You subtract your age in years from 220 e.g. 220 - 20 = 200 bpm. During exercise, your heart rate should reach no more than 60 ­ 75% of the maximal heart rate that you have calculated. To ease yourself into and out of exercise, it is best to have substantial warm up and cool down sessions.

A trained athlete's heart can pump more blood than average with each beat, therefore, his or her heart rate is slower. Likewise, an athlete's recovery time is shorter. Similar to the heart, the lungs have two ways to increase oxygen intake in response to a changing demand during exercise. One is to breathe more quickly (respiratory rate) and the other is to breathe more deeply (volume).

Advance preparation

• Check to see if any student should avoid this activity.

Helpful hints

• It is not essential to undergo each level of exercise for this activity e.g. a student may stop at brisk walking.
• The pulse can be felt at various points on the body where the arteries are just under the skin, such as the temples, neck, crook of the elbow, wrist, groin, back of the knee.
• The thumb should not be used when measuring the pulse. The thumb has its own pulse and may confuse your count.
• Do not press too hard when feeling for the pulse or you may block it.
• Heart recovery time can also be determined while doing this activity. After running, the pulse is measured and recorded every minute until it returns to resting heart rate. The time taken to return to resting heart rate is known as the heart recovery time.
• To measure breathing rate: breathing in and out once is counted as one breath, so just count the out breaths. Do keep in mind that it is difficult to accurately measure the effect of exercise on breathing as there is a certain degree of voluntary control involved.