Kyle Rulka  

&

Blake Gonzalez

(Research Proposal, KAAP400-011 - Fall 2016)

Title:

Effects of Different Exercise Protocols on Hypertension

University of Delaware

November, 201 6

Abstract

Exercise training has been shown to benefit hypertensive individuals by lowering their blood pressure over time.  There is little evidence separating one type of exercise from another type by their ability to lower blood pressure. The purpose of this study is to find evidence that would help medical professionals suggest a type of exercise that is optimal for lowering blood pressure, to individuals with hypertension.  100 participants (males age 20-50 with blood pressure readings >140/90mm Hg) will be broken into 5 groups of 20 and given exercise protocols to complete 3x/week  for 12 weeks.  These exercise protocols are swimming, running, weight lifting, yoga, and going to the park(control).  The participants will be taking their blood pressure 3 times a day for the 12 weeks to track any changes.  It is predicted that all groups (except for the control) will experience a decrease in blood pressure due to exercise.  The group with the greatest decrease is predicted to be the swimming group, followed by running, yoga, and weightlifting, respectively. This study will assist medical experts in suggesting the most optimal type of exercise to patients with hypertension, which in turn will help facilitate a decrease in their blood pressure and a decrease in the prevalence of hypertension as a whole.  

Keywords: Blood pressure, sphygmomanometer, swimming, health risks, and heart disease

Introduction:

Hypertension is the single biggest contributor to the global burden of disease and to global mortality.16 In 2008, approximately 40% of adults aged 25 and above had been diagnosed with hypertension and the total number of people worldwide with the condition was around 1 billion.21  Hypertension (also known as high blood pressure) is defined as having a blood pressure high enough that long term conditions may cause health problems, such as heart disease, heart attack, or stroke.8  Blood pressure is the measured pressure that is exerted by the blood against the walls of the arteries while circulating through the body.8  Blood pressure is most commonly measured using a device called a sphygmomanometer.19  A blood pressure reading, given in millimeters of mercury, has two numbers associated with it.8  The first number corresponds to the pressure measured while the heart is beating (systolic pressure), while the second number corresponds to the pressure measured in between heart beats (diastolic pressure).8  These two numbers make up a blood pressure reading which is used to diagnose an individual with hypertension.  A diagnosis of hypertension should not be given until multiple high readings have been taken across several days.9  A normal blood pressure reading is <120/80mm Hg, while hypertension is characterized by a blood pressure of >140/90mm Hg.7  There are other categories that a reading can fall into such as prehypertensive (120-139mm Hg systolic or 80-89mm Hg diastolic) or hypertensive crisis (>180mm Hg systolic or >110mm Hg diastolic).7

        Hypertension complications account for 9.4 million of 17 million deaths every year attributed to cardiovascular disease.14,21 This number is projected to rise as more individuals are diagnosed with hypertension each day than ever before.21  A staggering 80% of these deaths take place in low-income and middle-income countries.21  The prevalence of hypertension is highest in Africa at 46% of adults above age 25, and it is lowest in the Americas at 35% of adults above age 25.10,21 The prevalence of hypertension is also higher in low-income countries (40% on average), than it is in high income countries (35% on average).21  Hypertension has more far reaching effects than simply increasing mortality rate worldwide.  The economic impacts of hypertension have been studied and it has been found that hypertension accounts for a large portion of healthcare related costs in countries.2 Altogether, hypertension is a global crisis that needs more attention devoted to finding solutions, most specifically in low-income countries.  

        One of the cheapest and most proven ways to reduce blood pressure is through regular physical exercise.3,4,13,14,17,20 This non-invasive approach to reducing blood pressure is key in fighting the rising global rates of hypertension.11 It is a cheap, cost-effective way for people to fight hypertension, making it perfectly suited for those in low-income countries where they cannot afford expensive medications.  There is extensive research on exercise and the mechanisms through which it causes a change in blood pressure.1,4,13,15,17 They are still not well understood as hypertension is a complicated disease with multiple factors that may contribute; all without manifesting obvious, diagnosable symptoms.9  These studies seek to further understand blood pressure and the underlying mechanisms, which may be of benefit to other researchers/clinicians, but gives no benefit to the average hypertensive individual, especially those in low-income countries.  More effort needs to be devoted to improving ways for these individuals to reduce blood pressure on their own. There has been evidence supporting aerobic activity as superior to anaerobic activity when comparing their ability to lower blood pressure.1,6 Nearly all of these studies compare the effects of walking/running to weightlifting and a control group.  There are other forms of aerobic and anaerobic exercises that need to be considered when testing types of exercise and their effect on hypertension, such as swimming and yoga.  Swimming is a more total body, aerobic exercise that could be more efficient than running at reducing blood pressure.  Yoga is an anaerobic exercise that combines meditation and exercise, which may yield additional benefits for hypertension 22 

        The problem that this study addresses is the rising rate of hypertension across the globe.  The highest prevalence of hypertension is in low-income countries that cannot afford more complex healthcare options like regular screenings and medications.  One of the best options for intervention in these countries is giving hypertensive individuals a regular exercise plan to complete.  The aim of this study is to find evidence about which type of exercise is the most effective at lowering blood pressure in hypertensive individuals.  It is predicted that in the study all exercise groups will experience a decrease in blood pressure, though the swimming protocol will experience the greatest decrease in blood pressure.  The information to be gained from this study is crucial to fighting global hypertension rates as it will allow medical professionals to prescribe the most optimal form of exercise to those individuals with hypertension.  Therefore, increasing the likelihood that those individuals will decrease their blood pressure out of the hypertensive range.  

Methods:

        Operational Definitions:

Sphygmometer : An instrument consisting of an inflatable rubber cuff that is applied to the arm and connected to a column of mercury next to a graduate scale. This instrument gives a blood pressure reading consisting of systolic and diastolic pressures.

Systolic Blood Pressure: Systolic blood pressure refers to the systole phase of the heart beat, when the heart pumps blood out into the aorta 23

Diastolic Blood Pressure: Diastolic blood pressure is taken during the diastole phase of the heart beat, the resting period when the heart refills with blood 23

ANOVA Test: Statistical test to view significant differences between means of independent groups.

        Subjects: The study will consist of 5 groups of participants with each group having 20 members for a total of 100 participants (1 control group with 4 experimental groups).  The participants for the study will be found by examining medical records that were obtained through cooperating physicians we consulted for the study.  The participants will all be males age 20-50 years old who have known hypertension, with blood pressure readings >140/90mm Hg.  When individuals agree to participate in the study they will be given a questionnaire that will provide us with basic information such as physical activity level, occupation, general diet choices, and current medications/drug use.  We will select individuals who are currently at a low-moderate activity level so that the full effects of the protocol can be observed.  From the information on the questionnaire we will also be able to exclude participants that may have other variables influencing their blood pressure.

We will exclude any individuals who have blood pressure readings >180mm Hg systolic or >110mm Hg diastolic, as these readings indicate hypertensive crisis and these individuals would be better suited seeing a medical professional as soon as possible.7  Any participants who are deemed not healthy enough for regular exercise will be excluded from this study for risk of injury.  Any individuals who have other cardiac issues such as previous myocardial infarction, cardiac ischemia, aneurysms, etc. will be excluded as well for risk of injury.  Any individuals who are currently taking medications for hypertension (beta blockers, Thiazide diuretics, calcium channel blockers, etc) will be excluded to remove their effects on blood pressure from the data.5  Any individuals who are regular smokers and/or drinkers will be excluded from the study due to their noted effect on blood pressure and the inability to control consumption.21 The study will include only men to limit the effect that the biological differences between men and women could have on the data.21  The age range was chosen because most men within that range will be capable of a low-moderate intensity exercise protocol and the study will be focused on middle-aged adults, rather than younger or elderly individuals. This age range should also provide an adequate amount of participants with hypertension.21

Finally, when all participants have been selected they will be given a consent form to read and sign that fully explains the research.  On the consent form we will detail the procedure of the study, the expected outcome and benefits of the study, the level of discomfort they may experience during exercise, that they may ask any questions they have about the study, and the fact that they are allowed at any time to discontinue their participation in the study.

Variables: The independent variable for this study will be the provided exercise protocol for the individual to follow.  The dependent variable will be the change in blood pressure that the individual experiences due to the exercise protocol.

 In order to examine the relationship between these two variables several other factors will be controlled in the study.  The participants will have to cease all other exercise that they normally engage in to ensure they are not experiencing benefits from the extra exercise.  The participants will take their blood pressure at the same, designated times everyday.  The participants will be instructed to continue with their usual lifestyle choices so that any changes in blood pressure can more reliably be attributed to the exercise.  

Several other factors may prove to be confounding variables in the study, but with the steps taken to control certain variables their effects are predicted to be negligible.  These variables include occupation, stress level, dietary choices, and other general lifestyle choices such as home environment.21

Instruments: In order to regularly and reliably administer blood pressure readings to the participants we will give each one an automated sphygmomanometer.19  These will all be calibrated beforehand to ensure accuracy and the participants will all be instructed on how to use the sphygmomanometers before beginning the study.  Each participant will also need regular access to a computer where they will input their blood pressure readings to an Excel spreadsheet.  The participants will be given access to the University of Delaware gymnasium to complete their exercise protocols so the only instrument the participants must have is proper exercise attire.  

        Design and Procedures: The study is a longitudinal, cross over interventional study that will take place over a 12 week time period.  The 5 groups of 20 participants will each be randomly assigned an exercise protocol (with one of these being a control protocol) to complete 3 times a week for the 12 weeks.  The exercise protocols will consist of swimming, running, weight lifting, and yoga, while the control group’s protocol will be to sit on a park bench.  In addition to completing the exercise protocol at the 3 specified times a week the participants will  be taking blood pressure readings at 3 specified times each day with the provided sphygmomanometers.

To develop exercise protocols that are of a consist difficulty for all participants, the MET values of the exercises will be calculated so that all groups are completing the same volume of MET minutes per week.1  The total number of MET minutes per week will be around 750 minutes for all groups so they engage in the same amount of exercise, even if the actual time of exercise is different.  The intensity of each workout will be on the lower end of the MET scale at 2.5 MET’s as there is evidence supporting lower intensity exercise as more effective at lowering blood pressure.1  The exercise protocols will stay consist with the activities that the participants must complete each week.  The control group’s protocol will act as a placebo effect as they will spend a similar amount of time sedentary, while the other groups exercise.

The individual exercise protocols will be simple to learn exercises so that participant ability is not a major determinant of exercise success.  The swimming protocol will be a freestyle stroke at the calculated pace for the allotted amount of time to achieve the goal MET minutes.  The running protocol will be a run on the indoor track at the calculated pace and time to reach the MET minute goal.  The weight lifting protocol will consist of 5 different basic exercises (Squat, Push up, Pull up, Overhead Press, and Horizontal Row) that will have their MET values calculated at certain weights so that a set number of repetitions will be completed to reach the MET minute goal.  The yoga protocol will consist of several poses (Warrior stance, Downward Dog, Tree pose, etc.)  and their respective transitions that will have their MET values calculated so a set amount of time is spent in each pose.  Finally, the control group’s protocol will be to go to the park and sit on a bench for a similar amount of time that the other groups spend exercising.

The blood pressure readings will be taken 3 times a day at identical times to account for intra-day blood pressure changes.  The participants will use the automated sphygmomanometers to take their blood pressure readings from their right arm every day.  The times to take the blood pressure readings will be 15 minutes after waking in the morning (before food), at mid-day before lunch, and 15 minutes before going to bed at night.  These three readings will be recorded in an Excel spreadsheet that will be submitted at the completion of the study.  

        Assumptions & Limitations: The study will operate with a few assumptions of the participants.  The participants are assumed to exercise at every designated time and give their full effort while exercising.  The participants are assumed to continue with their lifestyle choices that they noted on the questionnaire so that they do not influence another variable that may have an effect on blood pressure.  

        The main limitation to the study is the genetic/biological differences that naturally exist between individuals.18  The unique differences that each participant’s body may have, may influence the ability of exercise to lower blood pressure.18  With the other factors that are controlled in the study this limitation is predicted to have a negligible effect on the data.

        Data Processing and Analysis: Each participant will have their blood pressure calculated before the study begins to achieve a baseline value for each individual.  Each group’s starting mean blood pressure will then be calculated from these values to achieve a baseline for the group as a whole. The Excel spreadsheet that each participant submits at the end-of-the study will contain 3 blood pressure readings per day, for the 12 weeks of the study.  The 3 readings each day will be averaged to achieve a daily average blood pressure value to use for calculations.  The average daily blood pressure will then be graphed against time for each individual to find the overall change in blood pressure and examine the data for trends.  The end of study blood pressure value will be compared to the before study blood pressure value to find the change.     Each group will then have all 20 graphs combined and a linear regression will be applied to the graph to find an overall trend in blood pressure change for the group’s exercise protocol.  The end-of-study mean blood pressure for the group will be compared to the before study value to find the average blood pressure change per group.  These group trends will then be used to compare the exercise protocols to one another for effectiveness in lowering blood pressure.

        An ANOVA test will be used to calculate the significance between each exercise protocol and the related change in blood pressure.  This test will be used to support the relationship between the exercise and the change in blood pressure.  We predict that the test will reveal a significance between all exercises and their decrease in blood pressure, with the strongest significance coming from the swimming group.

Conclusions:

        The predicted outcome of this study is that all exercise protocols will result in a decreased blood pressure when compared to the control group.  The swimming protocol is predicted to have the largest decrease in blood pressure, followed by running, yoga, and weight training, in that order.  The evidence supporting aerobic exercise and its effect on blood pressure have lead to that prediction.  

        The significance of this study is its ability to assist medical professionals in their prescription of physical exercise for hypertensive individuals.  Due to the findings of previous studies it is almost unanimously agreed upon that regular physical exercise will lower blood pressure for an inactive individual.3,4,13,14,17,20  There is a lack of evidence for a suggestion of one modality of exercise over another, which is what this study aims to provide.  The data from this study can be used by medical professionals to prescribe a certain type of exercise that has evidence to support that it is the optimal exercise for lowering  blood pressure.

 Looking forward, there are many opportunities for additional research that may build off of this study.  The exercise protocols can be adjusted to examine the difference between different lengths of exercise or frequency of exercise, as there has been evidence shown that these factors may affect ability to lower blood pressure.12  Additionally, once there is evidence to support an optimal form of exercise, that exercise can be further studied to see if there are ways to optimize its blood pressure lowering potential.

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