Effect of exercise on blood pressure.

Sarah Dawson 11V4

Research

The heart is made almost entirely of muscle. It is a hollow organ that pumps blood around the body and is in the centre of the circulatory system. It is divided up into four chambers: Two atria or auricles situated in the upper part of the heart, whose function is to receive blood. Two ventricles, situated in the lower part of the heart whose function is to pump blood.

The average heart rate of an adult is around 60-90 bpm (beats per minute) and blood pressure of 120/80, while resting, With each beat pumping 5 ounces of blood, which is approximately 4,000 gallons a day. The heart rests in between beats so it rests more then it works, so in a 70-year lifetime the average human heart works for about 30 years and rests for about 40 years.

When we exercise our heart rate increases. This is because our muscles are working harder and need more energy. Our heart rate increases to supply more oxygen, carried in the blood, to these muscles. The oxygen is needed in the muscles for aerobic respiration that is to break down glucose, which we get from food, into glycogen, which is the main type of energy we use when we exercise. This can be shown in the word and symbol equations:

Glucose + Oxygen → Energy + Carbon dioxide + Water

C6H12O6 + 6O2 → E + 6CO2 + 6H2O

Exercise is good for us and can make us fitter by making our heart work harder. The heart gets bigger and rests in between beats for longer, therefore becoming more efficient. People who are not fit do not get enough oxygen pumped to their muscle even though their heart still beats fast; the muscles build up an oxygen debt. Because the muscles are not getting enough oxygen they start respiring anarobically, that is, without oxygen. This type of respiration produces much less energy then aerobic respiration and produces lactic acid.

Blood pressure is a measurement of the force applied to the walls of the arteries as the heart pumps blood through the body. The pressure is determined by the force and amount of blood pumped, and the size and flexibility of the arteries.There are 2 types of blood pressure, Diastolic blood pressure and Systolic blood pressure. Blood pressure readings are usually given as 2 numbers e.g. 120 over 80 (written as 120/80). The first number is the blood pressure reading, and it represents the maximum pressure exerted when the heart contracts. The second number is the diastolic blood pressure reading, and it represents the pressure in the arteries when the heart is at rest.

Planning

Aim

The aim of this investigation is to examine the effect of exercise on blood pressure.

Prediction

I predict that my blood pressure after exercise will be faster than my resting rate. I know this because of my research, i.e. my heart will have to work harder to supply more oxygen to the muscle for aerobic respiration to take place and supply energy.

Apparatus

Sphygmomanometer- reads blood pressure
2 Stopwatches
A human subject
A suitable room

Obtaining evidence

Safety

As this experiment did not involve any acids or dangerous chemicals there ...

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Planning

Aim

The aim of this investigation is to examine the effect of exercise on blood pressure.

Prediction

Apparatus

Sphygmomanometer- reads blood pressure
2 Stopwatches
A human subject
A suitable room

Obtaining evidence

Safety

As this experiment did not involve any acids or dangerous chemicals there weren’t many safety issues. But some of the safety matters I shall observe while conducting the experiment are mentioned below-

As we were conducting the experiment in a school classroom, we had to make sure that there were no any dangerous objects that we could trip over and no sharp edged we could run into.
We were to use the Sphygmomanometer very carefully, making sure we did not put it on to tight.
As we were working in a classroom with other groups, we worked in our own space, and carried our exercises sensibly.

Fair test

Our experiment is about how blood pressure is affected by exercise. It crucial that we obtain reliable results, so we have to make our experiment a fair test. I will follow these steps to ensure that my results are trustworthy:

We have to keep the same person throughout. This is because every person has a different diet, fitness level, weight, build or is a different gender. All these factors affect a person’s heart rate.
The trial must be taken on the same day. The person’s health may be different or they may haven taken caffeine or medication, which could or risen or lowered their heart rate.
We must measure the person’s heart rate after exercise in the same position as when we took their resting blood pressure. If we do not we will not get accurate results. If the person were standing instead of sitting while their blood pressure is being taken, the heart would rise because the muscles are working to keep the person standing.
The pace of the person doing the exercises, because this will affect the person’s blood pressure. Because our test uses the leg and arm muscles repeatedly, the person must rest between each trial so that all the lactic acid can be carried away.
How long the exercise will go on for, I have decided to make this one-minute. Each exercise must take the same amount of time so that I can compare the blood pressures.

So my fixed variables are: keeping the same person, the same time, same positions, the same pace of exercises, and the time of the exercises. I will also repeat the experiment 3 times, which has allowed me to work out an average. Therefore this made the reading more accurate.

Method

1) First we thought of which exercises to choose for our subject. We decided to use walking, jogging, start jumps, and step-ups. We then set up all the equipment needed

2) To start with we measured each person’s blood pressure in the group to see which individuals blood pressure was nearest 120/80 (average persons blood pressure). This was to ensure we did not get anomalous results.

3) Once we had chosen our subject we measured the persons resting heart rate where there was no strain on the muscles. We decided to sit down while taking our blood pressure. If there were any strain on the muscles this would make our results unreliable because it would increase the blood pressure.

4) The subject then carried out the exercise for 1 minute, while 1-person timed it and then we took down their blood pressure. Another person timed how long it took for the blood pressure to return to normal. We recorded the results.

5) We repeated this for each exercise and repeated it 3 times to gain accurate results.

Analysing evidence

Results

Averages

Conclusion

My results show me that that my blood pressure after exercise will be faster than my resting rate. From this investigation I have learnt that the blood pressure goes up when exercise takes place. From the results you can see that there is a very quick increase in blood pressure once the exercise had started. This means that as the cells needed to respire a lot more as soon as exercise had begun. This is because my heart had to work harder to supply more oxygen to the muscle for aerobic respiration to take place and supply energy. My results show me a pattern that the more vigorous the exercise, then the higher the blood pressure. However I believe that my walking for my systolic results may be an anomaly because the blood pressure after exercises is lower than the resting blood pressure, and this goes against the pattern. Overall my results comply with my prediction.

Evaluating

Evaluation

I believe that I have a firm conclusion. I have determined this due to a number of factors. We repeated our results three times in order to take an average, which would produce more reliable results. All our results were of a similar pattern. There were no anomalies that were totally unexpected and completely went against my prediction.

Throughout the experiment I kept the following things the same to ensure reliable results:

-We measured the first beat of the heart,

-We kept the same person throughout the trials,

-The trial was taken on the same day and not in intervals,

-The pace of the exercise was kept constant,

-Starting blood pressure was always the resting blood pressure,

We controlled all the above variables that could have affected our results.

Our experiment was fairly accurate, we measured the carotid artery and although this is not a direct measure of the heart, the ripple felt is directly proportional to the heart rate. So as a result by measuring the pulse rate we were measuring the heart rate.

There were areas of my experiment that would question the reliability of my results. The pace of the person carrying out the trial may have changed during the trial. Even though another person was counting on a stopwatch the exerciser may have not kept the pace of the exercise constant. When one trial was over, and we would be lying down relaxing so that our heart rate would return to normal, we did not account enough time for the lactic acid in our muscles to be carried away. We would not be able to judge if all traces of lactic acid had indeed been carried from the muscles.

As the trial was being carried out the body temperature of the exerciser was rising. The heat of the body would increase the blood pressure, which would adversely affect our results, making them less accurate and reliable. The food consumed by the participating people may have contained different amounts of fats, carbohydrates and lipids. This would affect their available glucose levels during exercise.

To improve upon this experiment I would increase the amount of times it is repeated, to give a wider range for the average to be taken from. I would make the experiment longer to be able to see if the blood pressure will actually level out and at which point. I could have also carried out all the experiments in the same day, because the breakfast etc. may have changed throughout each day. However, this was difficult to do because we only had a lesson to carry out the exercises.

Further experiments I could carry out within my aim could involve exercising different muscle groups of the body. This could show which muscles need the most amount of blood supply. I could also try different intensities of the exercise carried out, by doing them for longer.