Prediction: I predict that the longer I exercise for, the higher my heart rate will become.
Theory:
When we exercise we need energy. We need to respire to create this energy. In our cells, respiration takes place all the time. Energy is released from glucose in tiny structures called mitochondria. Respiration must increase during exercise due to the higher demand of oxygen to the muscles. This means the body will have to work harder therefore the heart will need to increase. If the body is unable to continue aerobic respiration anaerobic respiration will take place. This results in lactic acid being formed. Finally, the CO2 levels would also rise which would also contribute to the heart rate rising.
Controls and Fair test
I am going to keep the type of exercise the same and the pace. I will be running on the spot for different times. This will ensure a fair test. I will change the length of time to get results. I will take my resting rate, running on the spot for 30 seconds, 60, 90, 120, 150 and 180. Although the temperature is out of my control, so I will try to take the results on the same day. Further more I will take each result (including resting rate) three times to ensure reliable results.
Apparatus:
- Stop watch
- Sensible and safe shoes.
Safety:
During the experiment, there are no major safety hazards, although I have conducted a list to follow to ensure safety:
- Clear ample space required (in the lab) for the exercise.
- Make sure the floor is not slippery or hazardous in any way.
- Make sure sensible shoes are worn (trainers.)
Method
- Firstly take resting pulse rate three times and record the results. To take my heart rate I will find my pulse on my wrist or neck. I will then time 30 seconds while simultaneously counting the pulse. I will then double this to get one minutes worth.
- Next jog on the spot for the selected amount of time (i.e. 30, 60, 90, 120, 150 and 180. )
- Then take pulse rate and record the results.
- Wait for pulse rate to return to resting rate, then repeat step ii and iii two more times.
- Lastly repeat all steps until all results are collected and represent it in a table.
Results:
Graph:
Conclusion:
The graph shows that there is a stable gradient to the points. They show that as the length of exercise goes up, the higher the pulse rate becomes. My prediction was correct. The graph shows that the heart rate increased at a steady rate. However, during the final minute the heart rate doesn't increase much at all. After each interval the heart rate does not return to normal straight away. This is because during the exercise anaerobic respiration begins to take place therefore the body has to pay back that oxygen back when it is resting. Therefore, when the exercise is complete the body's heart rate does not immediately return to the normal resting pulse rate. This is because of the pay back the body has to complete first. After two minutes, after the exercise is complete, the heart rate begins to gradually fall as the pay back becomes complete.
Evaluation:
Although I believe that my experiment produced fairly valid results, I am not sure that my experiment was particularly accurate. For instance, I cannot be sure that the jogging on the spot exercise was done at the same rate throughout the experiment.
If I were doing this experiment again I would have to look closely at the method of exercise I used. I think that exercising on a piece of equipment like a running machine would produce more accurate results because I would be able to guarantee that the exercise remained constant throughout this experiment. Jogging on the spot is not reliable as the pace can change easily. Furthermore the experiment was taken over two days,(this is because our lessons are not long enough) this could have altered the results as pace and energy levels could have changed. So if I was to do it again, I would arrange a suitable time slot so that the experiment was completed as fairly as possible
Finally, an actual 'pulse-meter' might have helped the experiment to be more accurate. This is simply strapped round the chest of the person during exercise and measures your current heart rate. I believe that this would produce a more accurate heart rate and destroyed the problem of my heart going back to resting rate.
To further the experiment I could look at a different range of activities and have a wider range of times. This would allow me to make a fully valid comment.
