Experiment report: effect of exercise on blood pressure Essay Example

Abstract

Blood pressure (BP) is one of the primary vital signs .It refers to the force that is exerted by blood circulation against the walls of blood vessels. Blood pressure can be described as the arterial pressure in the systemic regulation. The hearts’ pumping action is mainly the cause of blood pressure. The resistance of flow caused by blood vessels influences the rate of mean blood flow. Blood pressure measurement is conveyed by measuring the pressure at the upper right arm of a person and refers to pressure of the major artery found in the upper arm and the brachial artery (Pesola, Pesola & Westfal, 2001).

Blood pressure in a person is usually measured in millimeters of mercury (mmHg) and is given as an individual’s systolic pressure over diastolic pressure. Blood pressure can be normal, low or high. High blood pressure (hypertension), is a chronic medical condition whereby, blood pressure is elevated in the arteries .This causes the heart to pump harder than is normal so as to enable flow of blood through the blood vessels. Hypertension causes major health risks such as, artery aneurisms, stroke, heart attacks, and chronic kidney disease.

Introduction

High blood pressure is a primary cause of shortened life expectancy. Physicians have frequently recommended diet change, drug prescription, dynamic exercise and aerobic exercise in order to rest BP. The long term effects of physical training on resting arterial blood pressure have been studied widely over a long period of time..

The problem of how blood pressure is affected by exercise is significant for research due the fact that it is beneficial for understanding cardiovascular malfunction and general health. This experiment was undertaken in order to test if exercise has a major impact on systolic blood pressure, MAP, and diastolic blood pressure. The study would also test the hypothesis that blood pressure increases during exercise.

Methods

Nine students were randomly picked from the university without any medical screening beforehand. They consisted of both men and women.They were all different gender, age, body mass, and fitness level. However, the only requirement in order to take part in the experiment was that the subjects were able to do an exercise 2-5 minutes long.

Experimental design

The experiment did not focus on one type of exercise. That is, the subjects could perform any type of exercise they wished as long as it took 2-5 minutes long. The instrument used to measure the blood pressure was a sphygmomanometer, an instrument made up of a stethoscope, pump, valve, dial and arm cuff. The cuff was positioned around the upper arm and then the pulse was checked by use of the stethoscope. An accurate measurement of blood pressure was taken by hearing the sound of the pulse beats after the cuff was released. Before the blood pressure was taken, the subjects were to rest for at least five minutes and then they were required to empty their bladder. In order to acquire an accurate reading, the subjects were supposed to be sitting down and they were supposed to remain silent and make no movements. The systolic measurement was observed first followed by the diastolic reading. The blood pressure was measured twice, that was before and after exercise.

Statistical analyses

The variations from pre exercise to post exercise protocol were analyzed by use of a paired sample t-test. The descriptive statististics are given as means +-SE. Once the change of variables was derived, a regression equation was applied to denote the determinants of the change of both the systolic blood pressure and the diastolic blood pressure. The statistics were performed by use of SPSS. The level of significance applied was P<0.05.

Results

Table 1. Effect of exercise on blood pressure

The systolic Bp in the subjects increased after the exercise from 112 mmHg to 14.0 mmHg. The diastolic Bp increased after exercise from 75 to 85.Pulse pressure increased after the exercise session from 37 mmHg to 60 mmHg .HR also increased post exercise from 64 to 132.MAP increased post exercise from 87.3 to 100 mmHg. The average SBP, DBP, HR ,Pulse Pressure, and MAP also increase respectively post exercise.

Figure 1. Plot of blood pressure response before, during, and after exercise for the subjects.

Discussion

The blood pressure was taken while the subjects were sited down. The reason for this was that the arm should comfortably be at the level of the heart, positioned horizontally. If the arm is left hanging down (standing position), the blood pressure may be falsely lowered by a significant difference of 12mmHg.

The systolic pressure increases gradually during exercise. This happens as the cardiovascular system works to deliver adequate oxygen to the active muscles. The systolic pressure increases due to the fact that blood pressure is determined by two things; systemic vascular resistance and cardiac output. The heart rate and stroke volume controls the cardiac output .The heart rate increases during exercise (due to the increased metabolism and greater demand for blood flow to the muscles) and as more blood goes back to the heart the stroke volume increases too. Because of this increase in cardiac output, the systolic blood pressure increases. During exercise, the heart rate (HR)increases and the diastolic pressure remains about the same or goes slightly lower due to the fact that the blood vessels are dilated in order to help heat escape. The heart rate also increases due to the release of lactic acid and adrenalin into the blood stream. The pulse pressure is the difference between the systolic pressure and the diastolic pressure. During a cardiac cycle the average pressure is called mean arterial pressure. Both pulse pressure and MAP increase during exercise due to the fact that every time the body needs extra energy it makes use of oxygen to disintegrate adenosine triphosphate (ATP) and glucose. Whenever we do anything strenuous, there is increase in BP due to the fact that oxygen is carried by the blood. During exercise, the heart pumps harder and faster thus a large amount of blood is pushed into the fixed normal space of the blood vessels. Arteries cannot expand to contain the extra blood thus the BP raises.

Conclusion

Similar to the hypothesis, the results of the exercise showed an increase of SBP,DBP,HR and MAP as the exercise levels increased. Blood pressure increases in direct proportion with the intensity of exercise.

References

Caro, Colin, G. (1978). The Mechanics of the circulation: Oxford shire: Oxford University Press.

Dampney, R.A.L., Coleman, M.J, Hirooka & Tagawa ,T. (2006) Central Mechanisms Underlying Short-term and Long-term regulation of the Cardiovascular System, University of Sydney, Australia: Department of Physiology and Institute for Biomedical Research.

Pescatello, LS., Fargo, AE ., Leach, CN & Scherzer, HH (1991) Short-term effect of dynamic exercise on arterial blood pressure, Greenville Avenue, Dallas, TX: American Heart Association.

Pesola GR, Pesola HR, Nelson MJ, Westfal RE (2001). The normal difference in bilateral indirect blood pressure recordings in normotensive individuals: American Journal of Emergency Medicine 19 (1): 43–5.

Williams, B, Poulter, NR, Brown MJ. (2004). Guidelines for management of hypertension: report of the fourth working party of the British Hypertension Society, Hum Hypertens 18 (3): 139–85.