Apparatus List
- Stool-15cm step
- Stopwatch
- If necessary, a stethoscope
Diagram
Range of Measurements
I have decided on my range of measurements after carrying out a preliminary experiment. The preliminary experiment told me that the more step-ups I do in a minute, the higher my heart rate will become. This will also increase my recovery period, which is the time taken for my heart to return to its normal resting heart rate. In the preliminary experiment, I only took 2 sets of results just to see what the outcomes would be like. I did the exercise at 1 step-up per 3 seconds, and 1 step-up per 2 seconds. My results were as follows:
Resting Pulse Rates: 74bpm, 76bpm, 75bpm
Exercise 1:- After 1 minute=96bpm
2 minutes=84bpm
3 minutes=72bpm
Exercise 2:- After 1 minute=105bpm
2 minutes=81bpm
3 minutes=73bpm
I have concluded that if I were to increase the intensity of what I am doing, by increasing the number of step-ups every minute, I would have a higher heart rate after exercise.
This has helped me to decide this range of measurements for the main experiment:
- 1 step-up every 3 seconds=20 per minute
- 1 step-up every 2 seconds=30 per minute
- 2 step-ups every 3 seconds=40 per minute
- 1 step-up every second=60 per minute
- 3 step-ups every 2 seconds=90 per minute
From these measurements, I think I will obtain a good set of results covering a wide range of intensities.
Variables
Independent Variable- The number of step-ups per minute (the rate of exercise)
Dependant Variables- The pulse rate after exercise (beats per minute)
The time taken for recovery (minutes)
Controlled Variables- The height of the step (metres)
Time for step-ups (1 minute)
The time we measure our heart rate for (minutes)
Controlling rate of exercise during the minute (using a clock)
The person doing the exercise
The equipment used
Safety- to make sure this experiment is safe, I will be making sure that the stool that I am using to set-up on to is against a wall so it does not slide about.
Fair Test- This will be a fair test because I can measure accurately, the height of the step and the number of step-ups per minute. The height of the step will always stay the same. It also means that I can compare results as it is fair. The only thing that might make it unfair is the step-up technique and whether it is efficient enough for me to complete the task accurately.
OBTAINING EVIDENCE
After following my method to highest degree of accuracy I could, I have come up with these results:
I have worked out an average resting heart rate so that when I draw my graph, this will be my starting point.
These are my results from the exercises:
ANALYSIS
I have drawn three graphs to show my results. The first graph shows my heart 1 minute after exercise at the different intensities. The second graph shows my heart rate 2 minutes after exercise at the different intensities. The third and final graph shows the time taken for the heart beat to return to its resting heart rate, after the exercises at different intensities.
I have drawn a line of best fit on the first graph because in my prediction, I said that the graphs would show direct proportion between heart rate after exercise and rate of exercise. From my results, the line would be a curve, which shows the inaccuracy of my results. However, the results do support my prediction in that as I increase my rate of exercise, I increase my heart rate.
The second graph was similar to the first graph because it depended on the results of the first graph as to what it would look like. I also drew a line of best fit on this graph for the same reason as before. These results were also slightly inaccurate because they were not in a straight line like I had predicted. It seemed to be the latter results which were the most inaccurate.
The third graph was different to the first two in that it was showing the length of the recovery period from the exercise at the different intensities. I drew a line of best fit to show direct proportion between the minutes for recovery and the rate of exercise. This also supports my prediction in a way, because the longer the period of recovery, means the heart rate has to drop down from higher.
The three graphs support my prediction where I said, ‘I predict that the more intense the exercise we do, the higher our heart rate will become’. Although the results did not form a straight line, with direct proportion, the lines of best fit showed the direction the results were in, which was all that could be done for this experiment.
EVALUATION
After following out my plan as accurately as I could, and recording the results, I believe that my experiment did work and did support my prediction but was not accurate enough. The graphs show that the results were quite inaccurate.
I found that the latter results at the higher intensities of exercise were the most inaccurate, and I think this is because I did not complete that exercise correctly and therefore came out with anomalous results. The first few results seem to be following a pattern of increasing heart rate with exercise rate although not quite directly proportional. This is why I have drawn a line of best fit to show what I think my results should have been and then I can see where it went wrong. I think the last exercise was not possible to complete accurately, and if I were to do this experiment again, I would include that final exercise. If I were to do it again I would choose more manageable exercises where the results would be accurate. I also think that my pulse rate reading after the exercising was not completely accurate, because of the element of human error in counting the beats per minute.
I think that I should have repeated the exercises a few times to see how my results varied and if my average results would have shown direct proportion. This is another place where I could improve for next time.
I think to improve the accuracy of the results; I would need to count my heart rate more accurately. To do this I would need to use either a stethoscope or a heart beat monitor, which would give me true results. However, a stethoscope could still leave the chance of human error in counting the beats per minute so I think a heart rate monitor would be most accurate. I would need to use straight after the exercises.
I would need to make sure that the exercises that I set out to do could be completed and were actually possible. For instance, the exercise where I had to do 90 step-ups in 1 minute; I do not think I actually did that many. This was because it is hard to do 3 step-ups in 2 seconds and also the fact when doing the exercise that quick meant I got fatigued towards the end of the minute and I was not reaching that required exercise rate.
If I was to do it again with these improvements, I would also repeat the exercise a few times so that my results were even more accurate and I could work out an average set of results.
I think my range of results would have to be changed because of the final exercise, and I would have to limit it to the first four exercises that I did. I think I would do an extra exercise at a lower intensity e.g., 1 step-up every 6 seconds, which would mean I would 10 step-ups in a minute.
