The heart rate of a human varies from 150 beats per minute in young children, to about 60 in the aged. However, I am going to investigate whether doing exercise may alter the rate substantially.

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Analysis

The graph shows that the heart rate didn't increase a huge amount for the first minute but then increased very steeply for most of the rest of the exercise. However, during the final minute the heart rate doesn't increase much at all. This happened because the supply of Oxygen to the muscles decreased, a lot of energy will be used up as the exercise took place, the body was unable to continue aerobic respiration and anaerobic respiration took place. This resulted in lactic acid being formed. Finally, the CO2 levels also rose which also contributed to the heart rate rising..

When the exercise was complete, the graph tells us that during the next two minutes the heart rate falls very dramatically however it doesn't return immediately to the resting pulse rate. 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 decrease rate then 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 step-up exercise was done at the same rate throughout the experiment. Also, I am not sure that the 30-second intervals were kept exactly to this timing.

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. Finally, an actual 'pulse-meter' might have helped the experiment to be more accurate. This is simply strapped round the chest of the exercise and it measures your current heart rate. I believe that this would produce a more accurate heart rate and destroyed any necessity to have the 30-second breaks during the exercise.

The people doing the breathing rate experiments are doing the experiment to see how fit each person is. They do this by timing how long it takes for their breathing rate to get back to their normal rate (the rate it was at before they started to do the exercise). The method they stated they would use is extremely vague and is not very concise. The experiment was to find the 'effect'. The experiment could have been improved if they had a specific effect that they were going to measure. An example of this would be to find out if boys were better than girls at jogging for 5 minutes.

There are also many things that are not fair about the test. Firstly, there is one male and two females. This means that if they were testing to see whether or not boys were fitter than girls they could get biased results. This would result because the two females they chose could be extremely fit and the male could be extremely unfit. To overcome this problem I would use an equal amount of males and females (5 males and 5 females). I would also make sure that each of the people being tested would have a uniform lifestyle. Although I could never be completely sure if they had the exact same lifestyle I would try to find the closest match. They also do not state which form of exercise they are doing and this means that one person could have been running at 5 miles per hour whilst another could have been cycling at 2 miles per hour. This meant that their method was not very suitable at all. I would change this by making them do a uniform exercise like jogging at 5mph. Other factors which made their method unsuitable were the way in which they measured the results. It looks as if they have asked each person to measure their own amount of breaths they have taken. I have come to this conclusion because Johns result seems to be anomalous. This was probably because he had measured his own result and had probably measured his exhaling separately from his inhaling. This would cause his results to double. A way to overcome this problem would be to use a heart rate monitor and a breath meter (respirator). This would guarantee that the results were accurate. I would also take an average by repeating the test at least 4 times. This would help me because one result may come out with odd results and this would be a way of making that result less affective. It would also ensure they were much more accurate.

To extend the investigation I could do another experiment using people with worse lifestyles. I could then compare these results with the ones I had obtained in the previous test to see how peoples lifestyles affects their breathing rate. I could also use more people as the more results I obtain the more accurate the results will be.

The Effects of Exercise on the Heart Rate

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... 136 124 120 128 3 128 152 132 144 140 4 156 160 152 156 156 5 172 176 164 168 172 Results of Effects of Exercise on the Heart Rate

Pulse rate per minute (beats)

Conclusion: The graph shows that as the length of exercise increases the pulse rate raises until it starts to level off. The highest increase in the pulse rate occurs between 0-1minute. The pulse rate rises by 22 beats per minute. Thereafter it continues to rise by 21 beats every minute. When the body is exercising the muscles respire to produce energy, so the muscles can contract. Oxygen is needed for this process; the oxygen is carried in the haemoglobin of the red blood cell. The heart and lungs need to work harder in order to get a greater amount of oxygen to the muscles for respiration. In muscle cells digested food substances are oxidised to release energy. These oxidation reactions are called cellular respiration. When muscles use oxygen in order to respire the process is called aerobic respiration: Glucose + Oxygen Carbon Dioxide + Water

C H O (aq) + 6O (g) 6CO (g) + 6H O (l)

Energy released = 16.1kJ/g glucose

The heart rate rises because during exercise, cell respiration in the muscles increases, so the level of carbon dioxide in the blood rises. Carbon dioxide is slightly acid; the brain detects the rising acidity in the blood, the brain then sends a signal through the nervous system to the lungs to breathe faster and deeper. Gaseous exchange in the lungs increases allowing more oxygen into the circulatory system and removing more carbon dioxide. The brain then sends a signal to the sinoatrial node to make the heart beat faster. As a result the heart rate would rise.

The 'Nursing Practice Hospital and Home, the Adult' explains in detail how the heart beats and how the heart would beat faster. It states that 'the cardiac cycle is the cyclical contraction (systole) and the relaxation (diastole) of the two atria and the ventricles. Each cycle is initiated by the spontaneous generation of an action potential in the sinoatrial node. Diastol ...