Blood Pressure

By Alwin Wen


The purpose of this experiment is to see how different body positions affect the blood pressures of people in order to see how beneficial body positions are to blood pressure.

Background Information

A common misconception that people have is that body positions have no effect on your mind or anything about you. This is entirely wrong. On the contrary, body positions have a very powerful effect on you emotionally. They may change your mood, the way you think, or what you may even be thinking about.

Some fairly simple facts about body positions affecting a person’s mind include when a person is sitting down. When people are sitting down, they tend to report a greater sense of power and action if they had their ankle resting on their thighs and arms resting on the back of chairs than people that sat in constricted positions like legs together, shoulders dropped, and hands behind their thighs. This is just one example of how body positions affect a person and their mind.

Body positions can also change a person’s mood and what they are feeling. A study in the European Journal of Social Psychology in 2008 found that when a person crossed their arms while trying to solve an unsolvable puzzle, they persisted longer at the task than those in a neutral position with their arms over their thighs. Even though a person crossing their arms can give the sense of defensiveness of disinterest, researchers say that this pose can be good for achievement. Another helpful body pose is tensing your muscles. Although this may seem weird, researchers say that this body pose helps with willpower. Subjects that clenched their fits or contracted their leg muscles better responded to various situations like having to drink a nasty health tonic or getting ice water dumped on them.

The old myth that smiling makes you feel better proved to be true by a study in Psychological Science in 2012. People that smiled while performing stressful tasks had lower heart rates than people that had neutral expressions. Donning a positive expression and smiling more in general gave a much more positive effect and gave people lower stress levels. In contrast, lowering eyebrows or frowning immediately gave a negative effect on mood according to a 2012 study entitled Emotion.

Sleeping positions also say a lot about a person. The most common sleeping position is the fetal position, where a person might hug a pillow or a stuffed animal while in this position. Out of 1,000 people, 41% surveyed said they slept in this position, with 51% of females saying they sleep in this position. People that sleep in this position are described as being artistic, emotional, and sensitive with the ability and capacity to have intense relationships.

Another popular sleeping position is the free fall position. In this position, a person sleeps on their stomach with their hands around their pillow and their head facing one side. People that sleep in this position are said to be gregarious, brash, and dislike criticism. They are also stubborn, persistent, and goal-oriented. Sleeping in this position is good for digestion. If you are suddenly sleeping in this position, there may be something you are afraid of.

Blood pressure is an important part of this experiment. Blood pressure is the force of the blood against the walls of arteries as the heart pumps blood throughout the body. Some factors that contribute to blood pressure, like age, race, and diabetes or other medical conditions are unable to be controlled but some are. Higher blood pressure can damage the body more in many different ways. Regular exercise and an active lifestyle are just a few things people can do to prevent high blood pressure.

High blood pressure is a dangerous thing that can severely damage your blood vessels and arteries. It can also cause heart disease and enlargement of the heart muscles. To avoid having high blood pressure, it is recommended that a person eat more than eight servings of fruit and vegetables a day if they are at risk of high blood pressure. Some foods that can help include apricots, oranges, grapes, potatoes, and more. Alcohol can also be detrimental and regular over-consumption can lead to high blood pressure. Smoking is also a contributing factor to high blood pressure.

Blood pressure can vary depending on body position. When a person stands, in order for enough blood to be pumped through your body, there must be enough pressure to propel it against gravity. However, when a person is lying down, the blood is able to flow more freely through the veins because the force of gravity acting on the body has changed, therefore requiring less pressure. The arm position also highly affects the blood pressure. When an arm is hanging down, the blood pressure can change by as much as 12 mm Hg.

The blood pressure measurements on different people may not be the most precise measurements. Some people have an imbalance in their autonomic nervous system. This is important to blood pressure measurements because the autonomic nervous system, or ANS, controls constriction (narrowing) and dilation (widening) of blood vessels. This helps regulate your blood pressure.

Blood pressure is regulated with a stethoscope. A stethoscope is a fairly simple object to use. The cuff of the stethoscope must be placed over the bare upper arm of the patient. It is important that the arm should be fully supported on a flat surface near your heart level. The patient should have their back and arm supported and their legs not crossing. Wrap the end of the cuff around the arm snugly and wait for the stethoscope to finish taking measurements.


I believe that if a person is standing up in a straight position, then their blood pressure will be higher. If a person is in a sitting or lying position, or in a position that requires less effort, their blood pressure will be lower.


You will need…

-50 volunteers

-A clear room

-A chair of some sort

-A timer

-A blood pressure meter


  1. You will need a test subject for experimentation.

  2. Make sure you have a blood pressure meter along with a timer.

  3. Have your subject stand in a straight pose, arms by their side for no less than 3 minutes.

  4. Once that time is up, wait 5 more minutes.

  5. Test the subject’s blood pressure with the blood pressure meter.

  6. Do the same thing in steps 3-5. except this time have the person sit down.

  7. Continue to repeat steps 3-5, making sure to do all 5 body positions:

-Standing up (BP1)

-Sitting down (BP2)

-Laying down (BP3)

-Squatting (BP4)

-Pushup Position (BP5)

8. Repeat trials if necessary


Independent Variable - Body Position

Dependent Variable - Blood Pressure

Control - Human Test Subjects

Experimental Groups - Body Positions

Factors Held Constant - Human Test Subjects & Original Blood Pressures

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  • After being in certain body positions for a certain period of time, people’s heart rates began to increase.

  • People in pushup position started breathing quicker and some were sweating due to being in an uncomfortable body position.

  • Blood pressure decreased in individuality and the average when it went from initial to standing to sitting to lying down. This is likely due to less stress on the blood to flow when lying down.

  • The squatting position and push up position had similar averages of blood pressure likely due to the fact that both acts required similar amounts of stress, which explains why both positions had people saying they felt lots of stress, pressure, and soreness. The soreness of their bodies after they were in the positions is likely due to lactic acid fermentation.

  • The most stable body position was when people were lying down.

  • People were breathing the steadiest when they were in a standing position, however they also reported feeling sore in their feet after standing for a long period of time.

  • The blood pressure meter, or sphygmomanometer, has been wrapped around the arm of a subject and is being tested to see their initial blood pressure in a classroom setting.

  • When we did this with many subjects, they were breathing very heavily and complained of hand and leg soreness. This may or may not correlate directly with the increased blood pressure.

  • In the picture, the subject is in push up position. The subject must stay in push up position for a certain amount of time in order to successfully get an effective blood pressure reading.

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% change from BLP1 average to BLP2 :

BLP1 - 113.95

BLP2 - 110.63

BLP1/BLP2 = 113.95/110.63 = 1.03000994 = ~3% decrease

% change from BLP2 average to BLP3:

BLP2 - 110.63

BLP3 - 106.32

BLP2/BLP3 = 110.63/106.32 = 1.040538 = ~4% decrease

% change from BLP3 to BLP4

BLP3 - 106.32

BLP4 - 113.56

BLP3/BLP4 = 106.32/113.56 = 0.93624516 = 1 - 0.93624516 = ~6.74% increase

% change from BLP4 to BLP5

BLP4 - 113.56

BLP5 - 115.17

BLP4/BLP5 = 113.56/115.17 = 0.98602067 = 1 - 0.98602067 = ~1.24% increase


% change from BLP1 to BLP2

BLP1 - 75.62

BLP2 - 73.45

BLP1/BLP2 = 75.62/73.45 = 1.02954391 = ~3% decrease

% change from BLP2 to BLP3

BLP2 - 73.45

BLP3 - 68.41

BLP2/BLP3 = 73.45/68.41 = 1.07367344 = ~7.37% decrease

% change from BLP3 to BLP4

BLP3 - 68.41

BLP4 - 72.97

BLP3/BLP4 = 68.41/72.97 = 0.93750857 = 1 - 0.93750857 = ~6.35% increase

% change from BLP4 to BLP5

BLP4 - 72.97

BLP5 - 74.34

BLP4/BLP5 = 72.97/74.34 = 0.98157116 = 1 - 0.98157116 = ~1.95% increase

Statistical Analysis

The graphs below show the variance, standard deviation, and standard error between the group, calculating the errors in the experiment and the samples of each blood pressure average and calculating through ANOVA the means, variances, etc.
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In the experiment it was found that the blood pressure did decrease when the body position moved from a normal standing position and then increased once it went back to positions that required effort, like the squatting and push up positions. The change and fluctuation of the blood pressure was observed during the experiment based on every body position to determine if there was a connection between the two.

In the experiment, the averages for body position 1 were at a reasonable level. However, when the body positions changed from standing to sitting to laying, it continued to decrease. For example, subject AE had a BLP1 of 116.42/75.54. However, in BLP2, it decreased to 113.52/75.51, which showed that standing required more pressure and effort than sitting. In BLP3 it reached its minimum, at 110.45, 74.01. While it may not be a drastic decrease compared to other subjects, it is still a notable change in blood pressure. It then rose up to 111.89/75.24 in BLP4, and then peaked at 113.10, 76.21 at BLP5. The reason for these increases is likely due to the fact that there is obviously more effort required in BP4 and BP5 than in BP3.

When we looked at our research, it said that when someone is in a position requiring more effort than another, there is more pressure needed in these positions to pump blood throughout the body, hence why most tests result in a higher blood pressure. When this test was conducted, we observed our subjects and how they reacted externally to see if the research matched out subjects. True to the research’s word, the subjects were breathing harder and had started to feel more soreness in push up position, one of the more effort requiring positions. This would correlate with the fact that this position had higher blood pressure averages, which would be important for someone with high blood pressure to know.


The original claim for the experiment was that as a body position changed from a normal body position to one that required less effort, the blood pressure would decrease. This was proven true in the experiment. The hypothesis was well supported by the data and there were over 200 trials overall to test the experiment. The purpose was achieved when the experiment was tested. The different body positions showed in the experiment how they affect the blood pressures of the different positions and it showed when the multiple trials were looked at and compared in relation to one another. If a person is standing or in a position requiring more effort, their blood pressure will increase, yet if a person is in a position of low effort, their blood pressure will decrease.

Sources of Error and Inaccuracies

In my experiment, we used a sphygmomanometer to measure the blood pressure of several different subjects. Our novice handling of the equipment could have led to faulty results as well as results that were not entirely true. At the same time, our time keeping may have been slightly off so the blood pressures could not have been entirely accurate, which would have been another problem in the experiment that may have affected the end results. This would have made our graphs somewhat unreliable as they took the averages of what could have been faulty results. I also rounded a lot of numbers to try and make them smaller to work with, which could have affected the averages when I took them to see how they matched with each other, because the numbers could vary give or take a few.


This experiment can be used in real life in various different ways. People with high blood pressure can use it to determine what body position they could be in in order to keep their blood pressure lower. People that may be nearing the high blood pressure threshold will be able to know how they should be spending their day so that they can avoid high blood pressure and stay healthy. Doctors may also need to know things like this so that they can better understand how high blood pressure can be fought and what they need to tell their patients in order for them to lower their blood pressure. It is important that people know this so that with just a few steps they can take their own measures to try and stop high blood pressure from affecting them. The results of this experiment can be used by scientists developing new medicines to combat blood pressure to investigate further on why this is the case. There may be something deeper that could lead to a medical breakthrough in relation to high blood pressure.


There are many things that could be changed in the experiment to make it more effective and have better results. We could learn how to use a sphygmomanometer more effectively so that there would be no miscalculations based on our usage of equipment. Along with the equipment used, we can also use multiple timekeepers in order to keep track of time easier and get more than one person’s timekeeping. We could also have person do two trials of each body position for more effective data that could be rounded easier. To expand on the experiment, we can test more body positions and not only would blood pressure be tested, we could also test heart rate to see if it has relation to blood pressure changing. The expanded amount of body positions tested would help make our data more reliable as well as provide more information on certain body positions and to check our background information.