Method
I am going to get my person to carry out several exercises for 2 minutes. Before deciding on this I did some preliminary work. This showed that exercising for 1 minute did not increase the heart rate hugely and that 3 minutes proved too difficult for my person.
The exercises I will carry out are:
- Step-ups
- Star jumps
- Skipping
- Jogging
I had originally planned to carry out more different other exercises but this was too much for my person to do, and so decided to do these four as I thought they would be good for the investigation
At the beginning of each of the exercises the resting pulse will be taken and recorded. The exercise will begin and the pulse will be taken and recorded a second time after the 2 minutes. I will then compare this with the original, heart rate, at rest.
I will repeat my experiment once more after this so that I will be able to take an average heart rate for each exercise and to ensure that no errors are made when recording my person’s heart rate.
Fair Testing and Safety
To ensure that the investigation is fair all of the exercises will be carried out on the same day to make it as accurate as possible. Weather conditions may change from day to day, and so therefore this could affect the heart rate for example on a hot day our heart beats faster then it does on a cold day. The same person will carry out the exercises each time. I will allow a further 3 minutes between each exercise to allow the heart rate to get back to normal.
As for the safety my person will carry out each of the exercises in a wide, open space. I have done this to hopefully avoid conflict with objects or other people especially when my person is using a skipping rope. Of course there is the danger of me being present during these exercises but I shall stand at a good distance and therefore I am present in case my person should result in an injury.
Apparatus
- Skipping rope.
- Steps
- Stop watch
Prediction
From knowledge of which I already know I predict that the rate of respiration will increase as a result of the exercise. I think that there will be a gradual increase to begin with, but as the body has to work harder I believe that the heart will then increase at a faster rate... The harder the person exercises the faster they will loose oxygen in my muscles therefore the heart will need to pump blood faster the more I exercise. When the exercise is complete I think that the heart rate will gradually decrease back to the resting pulse rate
Obtaining Evidence
I carried out my set of exercises twice to ensure an accurate set of results.
First set of results
Second set of results
Results (Taken from average)
As I needed to record all of my results on the same day to ensure that they were as accurate as possible and my testing was fair I did not have time to repeat my exercises a third time, if I had been able to do this then my results may have made my average results more accurate.
For the sake of my graph I have decided to show the increase in heart rate by using the average heart rate at rest, which was 74bpm.
Analysing and concluding
My graph shows the type of exercises against the heart rate after 2 minutes of carrying out each exercise. The points here have formed a straight-line graph. The graph shows that heart rate increases as we exercise, this is shown by the steepness of the line from the heart rate at rest. The graph also shows that the increase in heart rate after 2 minutes gets higher as the exercise become more energetic. As the graph gets steeper it shows that the more vigorous the exercise the faster the heart has to beat.
There is a genuine pattern in my results. My prediction I made earlier was correct, and that was the more intense the exercise, the faster the subjects heart rate. The reason this happens is because when you start moving at a faster pace the body uses up more oxygen, so therefore the body needs to provide more oxygen to replace it with the increasing carbon dioxide building up in the muscles.
The graph gets steeper because heart rate is increasing dramatically the more I exercise. This is because the heart has to supply more oxygen to the muscles when you take exercise so it has to beat faster.
If a person is not fit, although their heart beats faster they still do not get enough oxygen to their muscles so they build up an oxygen debt. This is because their muscles are respiring anaerobically and making lactic acid. It takes them a long time remove the lactic acid from their muscles. Anaerobic respiration occurs when oxygen is not available. Anaerobic respiration in muscles produces lactic acid, which is toxic and can cause cramp. A fitter person does not build up an oxygen debt so their muscles respire aerobically. In aerobic respiration glucose is combined with oxygen to be converted into carbon dioxide and water releasing energy.
Evaluation
Although a straight-line graph would normally indicate accuracy, this particular investigation was not very accurate at all. There were many factors in this. It was difficult to know whether the stop watch began at the same time as the person began the exercise and so therefore the timing of the exercise could not be 100%. Another problem I came across was that my person’s heart rate at rest was not exactly the same before the beginning of each exercise; this will have affected the increase in heart rate after 2 minutes and will also have affected the accuracy of my results.
Another problem was that I could not always find a pulse straight away and in the time it had taken me to find my pulse my person’s heart rate could have dropped although it would not have been very major, this too could have altered the accuracy of my results.
I tried to make my experiment as accurate as possible. All of my exercises were conducted in the same conditions on the same day as temperature and surroundings could have influenced my heart rate. I also carried out each exercise myself, there were many reasons for this, if I had used different subjects for each exercise things like sex, age and level of fitness would affect each persons heart rate and this would not have been fair.
My experiment was made less reliable by the fact that it has to be done by an individual and nobody could expect to get exactly the same results as the heart rate is affected by age, diet, sex, level of fitness, etc. Another thing that made it unreliable would be that the exercises would have to be carried out in exactly the same conditions each time and we can not predict how the weather will change from day to day as this is out of our control. Also not all of the equipment used will be the same each time for example the height of the step-ups and length of the skipping rope, reliability is lost if not everything matches.
There are several improvements that could be made to increase the reliability of this investigation. To begin with another person could be with the subject to take down recordings and check the heart rate of the person doing the exercises. Each exercise could be carried out under controlled conditions where light and heat are kept the same to avoid these factors affecting heart rate. Specific measurements for the height of the step-ups and length of the skipping rope so that all equipment used is exactly the same each time and everything matches. Another thing would be to make sure the heart rate was exactly the same at rest before the next exercise was begun as this significantly changes the amount that the heart rate increases.
The major thing that affects the reliability of this experiment is that it has to be done by an individual and no two people would ever get exactly the same results, as there are many factors that affect heart rate, which I have listed above. There is nothing that could be done to improve this as the investigation has to be conducted by a human being. However the title could be made more specific so that results could be compared, for example ‘Investigate the effects of exercise on the heart rate on two different individuals’
