Objectives:



PROJECT FINAL REPORT COVER PAGE

GROUP NUMBER: M4

TITLE: Can Significant Differences in Cardiovascular System Parameters Be Found in our Lab?

DATE: 12/21/01

ROLE ASSIGNMENTS

ROLE GROUP MEMBER

FACILITATOR Vikram Krishnan

TIME & TASK KEEPER Norman Cabanilla

SCRIBE Elizabeth Kim

PRESENTER Angela Xavier

Summary:

Blood pressure and heart rate measurements of two groups (Group A (active) vs. Group B (inactive)), consisting of two males and two females each, were taken at rest and after running at 3.5, 5.0, and 6.5 MPH. The division of the two subject groups was determined according to the amount of aerobically active exercise they maintained on a regular basis. The effect of regular exercise on heart rate and blood pressure increases during exercise was monitored.

Group B (inactive) was found to have larger values for every cardiovascular parameter (systolic pressure, diastolic pressure, mean arterial pressure (MAP), and heart rate), both at rest and post-exercise. The larger values at rest for Group B, however, were not found to be statistically different for any cardiovascular parameter; the larger systolic blood pressure and the heart rates values recorded by Group B were found to be statistically significant through all running speeds, while diastolic pressure values were found to be statistically the same between groups, under all physical conditions.

Group B showed a statistically significant higher increase in both systolic blood pressure and heart rate than did Group A, while the diastolic blood pressure remained statistically the same before and after exercise. In comparing the percent differences between the two groups, the rest values for all cardiovascular parameters for both groups were within 10% of each other. With an increase in the level of exercise, the percent difference between the two groups in values for systolic pressure continued to increase from a rest difference of 6.57% to a difference of 42.32% at 6.5 mph. This trend was similar for the MAP, where the difference between the two groups increased from 7.69% at rest to 29.39% at 6.5 mph. Heart rate values showed a steady increase in the percent difference between the two groups from rest to 3.5 mph to 5.0 mph (4.21% to 22.30% to 38.56%), but the difference dropped to 19.77% at 6.5 mph. This decrease in percent difference may be an indication of the theory that there is a genetically predetermined maximum heart rate for each person, which is independent of fitness.

The rate at which blood pressure and heart rates elevate after exercise was found to be faster in Group B than in Group A. For systolic blood pressure, mean arterial pressure, and heart rate, Group B produced larger increases post-exercise over rest than did Group A; this was the case for all running speeds. However, in most cases, these increases were not found to be statistically different between groups; this lack of significance can be explained by the low number of trials conducted, and the high level of unexpected variation in subjects’ readings between weeks of testing. Elevation in diastolic blood pressure did not show any trends between groups.

In terms of sensitivity to physical activity, the heart rate of a person appears to be the cardiovascular measure most affected by exercise; Group A registered an increase of 72.38% in heart rate after running at 6.5 MPH, while Group B registered a subsequent increase of 104.51% during the same trials. Heart rate is followed by systolic blood pressure and mean arterial pressure, with diastolic pressure being the cardiovascular parameter least sensitive to exercise.

Objectives:

The main objective of the experiment was to find statistically significant differences in blood pressure and heart rate between physically active and inactive subjects. The hypotheses tested and the results concluded would provide insight into the extent of the effects of exercise on cardiovascular health. The effects of high blood pressure are omnipresent in our society. If an engineering approach can be taken to the problem, analysis could explore whether or not extensive exercise could lower the chances of an individual developing high blood pressure. By designing the experiment correctly, the results would correlate to the hypotheses of significant differences between heart rates and blood pressures in groups of active and inactive individuals.

In order to achieve this main objective, several specific aims were identified. The first aim was to identify a group of four aerobically active individuals and four inactive individuals, as determined by the extent of physical exercise that each identified. Each group consisted of two males and two females. After the groups were assembled, the next aim was to measure heart rates and blood pressures at rest and through various states of exercise while maximizing the number of trials at each state, in order to minimize uncertainty levels. Upon completion of experimentation, it was determined if statistically significant differences existed between the heart rates and blood pressures of the two groups at 95% confidence by conducting t tests between the values of the two groups. The final aim was to determine at what confidence interval the values between the two groups were significant, if they were insignificant at 95% confidence. These intervals were determined by calculating the p values between the two groups at each parameter.

By defining the objectives and specific aims in the experiment, it will be possible to evaluate the hypotheses established prior to testing. These hypotheses include: Members of the active group will have significantly lower blood pressure and heart rate values than members of the inactive group at rest and after moderate exercise; after exercise, members of the inactive group will have significantly larger increases in blood pressure and heart rate than will members of the active group; and after intense exercise, there will be no trend in heart rate values within a group or between groups. The significant changes in blood pressure are expected to be present in the systolic pressure values, as well as the mean arterial pressure. Diastolic pressure is not expected to display changes during exercise.

Background Information:

The first reference utilized was the BioPac Pro( manual.1 The manual detailed the software used, as well as provided basic background information on heart rate and blood pressure. However, further information was needed to establish reasonable hypotheses.

The second reference consulted was Physiology, 4th ed. (Berne and Levy, eds.).2 The reference detailed the functions of the heart and how blood pressure is related to the cardiovascular system. The physiology textbook explained the meanings of systolic pressure, diastolic pressure, and mean arterial pressure. The reference provided the basic background information needed to understand the systems that were being studied in the experiment, as well as information utilized to formalize hypotheses about the outcomes of the experiment. The textbook explained how the heart and blood change during exercise, and how prolonged exercise may affect resting heart rates and blood pressures. Also the differences between changes in systolic and diastolic pressures during exercise were described.

Heart rate and blood pressure continuously change with the level of physical activity. Endurance training, such as running or swimming, increases left ventricular volume without increasing left ventricular wall thickness. In contrast, strength exercises, such as weight lifting, increase left ventricular wall thickness with little effect on ventricular volume. Systolic blood pressure increases more than diastolic pressure, which results in an increase in pulse pressure. The average resting heart rate is approximately 70 bpm in normal adults. During muscular activity, it may accelerate to rates well above 100. In well-trained resting athletes the rate is usually only about 50 bpm.2

In response to regular exercise, the cardiovascular system increases its capacity to deliver O2 to active muscles and for these muscles to utilize oxygen. After conditioning and training, athletes will experience a lower resting heart rate, greater stroke volume, and lower peripheral resistance than they had before training or after deconditioning (becoming sedentary). The lower heart rate results from the improved utilization and delivery of oxygen to the active muscles. This improved efficiency means less oxygen is necessary for the body to perform the same functions.2

The next cited reference was a MedLine article provided by the National Institutes of Health website.3 The site provided important information about the procedure for taking blood pressure and how to prepare subjects for testing. Also listed were the normal values of blood pressure for adults and what abnormal results could be interpreted to mean. The information was important to allow for determining which of the subjects could classify as “high” or “low” for the parameters of blood pressure tested.

Arterial blood pressure is determined directly by the arterial blood volume and the arterial compliance, which are in turn affected by heart rate, stroke volume, and peripheral resistance. Heart rate and stroke volume increase with physical activity, which leads to an increase in blood pressure. Blood pressure is continually influenced by physical activity, temperature, diet, emotional state, posture, physical state, and drugs. Diastolic blood pressure is the lowest amount of pressure in the arteries as the heart rests.3

There are many factors that influence your heart rate including age, genetics, training, overtraining, conditioning, illness, recovery, weather, hydration and nutrition. These factors may affect your resting heart rate, your maximum heart and your threshold heart rates in a variety of ways. Maximum, resting and threshold heart rates decrease with increasing age. However, the rate at which it decreases with age will be slower with consistent training. Resting heart rate will decrease with training. Illness will cause a rise in resting heart rate and lower maximum and threshold heart rates. However, heart rates will typically be higher than normal at any given pace or perceived effort. Your body is working overtime trying to fight off infection or a cold.3

The final reference consulted was an article in Medicine & Science in Sports & Exercise.4 The article detailed the changes in heart rates and blood pressures of athletes after intensive training and prolonged physical exercise. The effects of exercise on heart rate and blood pressure of these athletes offered a basis for formulating hypotheses prior to testing.

In this study by Wilmore, et al., subjects were taken through an endurance training period. Their resting and running blood pressures and heart rates were taken before and after the training sessions. The conclusions were that resting heart rate and blood pressure generally exhibited small decreases after the training, whereas exercising heart rate and blood pressure showed significant decreases after training.4

Materials and Apparatus:

The following subjects, materials and apparatus are necessary for performing the experiment:

1. BioPacPro® software.

2. BioPacPro® Acquisition Unit.

3. Stethoscope (BSL Model No. SS30L)

4. Sphygmomanometer and Blood Pressure Cuff (BSL Model No. SS19L)

5. Pulse Plethysmograph Transducer (BSL Model No. SS4L)

6. Treadmill

7. Test Subjects (Group A (active), 1A-4A; Group B (inactive, 1B-4B)

The BioPacPro® Software and Acquisition Unit will allow for the display of the electrical signals recorded during the experiment as a graph of voltage versus time. These graphs can later be analyzed using the BioPacPro® software.

The stethoscope (BSL Model No. SS30L), sphygmomanometer and blood pressure cuff (BSL Model No. SS19L) will be used to take blood pressure measurements throughout the experiment. The sphygmomanometer and blood pressure cuff are used to collapse the brachial artery, while the stethoscope registers the change in blood flow as pressure is released and the artery begins to open up as blood flow returns to normal. The stethoscope is attached to the acquisition unit, which converts these changes in blood flow to changes in voltage plotted versus time (“Korotkoff Sounds”). The pressures that coincide with the first and last Korotkoff sounds will be the measure of systolic and diastolic blood pressures, respectively.

The sphygmomanometer will be used to calibrate the blood pressure values produced by the BioPac software. A calibration curve will be constructed by plotting sphygmomanometer blood pressure readings (mm Hg) to BioPac blood pressure readings, and the equation produced from the calibration curve will be used to correct and standardize all BioPac readings.

The pulse plethysmograph transducer (BSL Model No. SS4L), or PPG, records a subject’s heartbeat as a pulse pressure waveform. The PPG is attached to the finger with a Velcro® strap. The PPG itself consists of a matched infrared emitter and photo diode. This senses changes in blood density and hemoglobin concentration. The changes in concentration are caused by variations in blood pressure, and correspond to the subject’s pulse.

The treadmill will be used to stimulate an aerobic workout in the two groups of test subjects during the running trials.

Protocols

Based on past experience, the BioPac Pro software has proven to give inaccurate readings for Blood Pressure on its own; in order to collect meaningful data from BioPac, blood pressure readings must be compared to actual sphygmomanometer readings, and a calibration equation must be obtained. At the start of each lab session, before any testing of subjects takes place, blood pressure readings on BioPac Pro will be plotted against blood pressure readings from the sphygmomanometer. The equation from this calibration curve will then be used to convert the BioPac readings into corrected blood pressure readings. In order to ensure any changes in the BioPac acquisition unit does not affect any measurements, a calibration curve will have to be constructed for each new day of testing.

For each subject, for any given state of rest or exercise (3.5 mph, 5.5 mph, 6.5 mph), Korotkoff Sounds and Blood Pressure will be recorded on Biopac Pro to determine Systolic, Diastolic, and Mean Arterial blood pressures. Also heart rate will be measured using the Pulse Plethysmograph (PPG) finger pulse device.

Procedure:

Two groups of four subjects, those with an aerobically active lifestyle and those with a sedentary lifestyle were selected based on the responses submitted in their respective lab groups. Two males and two females were in each group. The experiment was conducted over a period of three weeks. During the first week, each subject’s resting heart rate and blood pressure was taken for a total of six measurements. Then they were asked to walk on a treadmill at low incline at 3.5 mph for two minutes. Their heart rate and blood pressure were taken immediately thereafter. This was repeated for a total of three trials.

During Week 2, the subjects’ resting blood pressures and heart rates were checked, and then they ran at a moderate speed: 5.5 mph for two minutes with a 5-minute interval of rest between the three trials.

Similarly, in the third week, the subjects’ resting blood pressures and heart rates were checked, and then they ran at high speed (6.5 mph) for two minutes with a 5-minute interval of rest between the three trials.

•

Results:

Table 1: Test Subjects

[pic]Prose: Subjects for each group were selected based on their level of regular physical activity/exercise, as well as on any history of sustained exercise. The subjects in Group A were deemed to be “physically active”, while the subjects in Group B were deemed to be “physically inactive”.

Blood pressures (systolic and diastolic) and heart rates were measured and mean arterial pressures (MAP) for each subject while at rest and immediately after physical activity (running on a treadmill); subjects were tested after running for two minutes at 3.5, 5.0, and 6.5 MPH. The results of their tests are listed in Table 2.

Table 2: Raw Data for Systolic, Diastolic, and Mean Arterial

Blood Pressure, and Heart Rate Readings

|Subject |1A |2A |3A |4A |1B |2B |3B |4B |

|Week 1 |

|Average |127.65 |116.75 |104.75 |110.08 |117.15 |131.70 |126.31 |114.24 |

|Rest Systolic | | | | | | | | |

|Average |74.90 |77.60 |62.10 |62.92 |78.30 |84.95 |81.39 |56.78 |

|Rest Diastolic | | | | | | | | |

|Average MAP |92.48 |90.65 |76.32 |78.64 |91.25 |100.53 |96.36 |75.93 |

|Average |60.10 |68.10 |77.02 |59.99 |75.47 |71.89 |72.74 |56.28 |

|Rest BPM | | | | | | | | |

|Average 3.5 |135.85 |127.00 |109.69 |110.25 |136.19 |148.28 |146.88 |137.89 |

|mph Systolic | | | | | | | | |

|Average 3.5 |70.83 |75.61 |62.30 |71.18 |93.34 |87.69 |82.81 |65.50 |

|mph Diastolic | | | | | | | | |

|Average 3.5 mph MAP |92.51 |92.74 |78.10 |84.20 |107.62 |107.89 |104.17 |89.63 |

|Average 3.5 |58.47 |71.00 |77.86 |59.90 |79.62 |88.19 |78.20 |80.81 |

|mph BPM | | | | | | | | |

|Week 2 |

|Rest Systolic |105.86 |114.05 |93.19 |108.49 |115.37 |139.78 |117.18 |111.94 |

|Rest Diastolic |59.09 |72.62 |58.25 |61.92 |79.53 |110.57 |46.74 |57.93 |

|Rest MAP |74.68 |86.43 |69.89 |77.45 |91.47 |120.30 |70.22 |75.93 |

|Rest BPM |72.20 |82.19 |72.64 |63.34 |81.91 |92.07 |84.07 |57.16 |

|Average 5.0 |148.21 |149.82 |136.10 |133.23 |140.84 |183.37 |178.03 |185.49 |

|mph Systolic | | | | | | | | |

|Average 5.0 |77.47 |76.92 |67.88 |71.62 |78.75 |72.01 |76.72 |83.04 |

|mph Diastolic | | | | | | | | |

|Average 5.0 mph MAP |101.05 |101.22 |90.62 |92.16 |99.45 |109.13 |110.49 |117.19 |

|Average 5.0 |86.89 |114.81 |105.45 |83.57 |128.68 |130.46 |146.90 |135.36 |

|mph BPM | | | | | | | | |

|Week 3 |

|Rest Systolic |111.81 |89.12 |83.14 |103.48 |110.86 |129.35 |135.56 |113.33 |

|Rest Diastolic |64.68 |63.75 |46.03 |53.96 |78.99 |71.17 |75.35 |58.55 |

|Rest MAP |80.39 |72.21 |58.40 |70.46 |89.61 |90.56 |95.42 |76.81 |

|Rest BPM |66.77 |76.47 |91.87 |60.96 |77.97 |95.13 |77.54 |58.90 |

|Average 6.5 |143.68 |131.09 |101.77 |136.28 |155.35 |199.86 |194.44 |180.21 |

|mph Systolic | | | | | | | | |

|Average 6.5 |72.95 |60.12 |60.24 |56.18 |75.93 |71.08 |82.23 |60.43 |

|mph Diastolic | | | | | | | | |

|Average 6.5 mph MAP |96.52 |83.77 |74.09 |82.88 |102.41 |114.01 |119.63 |100.36 |

|Average 6.5 |65.58 |170.93 |152.65 |122.91 |131.41 |158.81 |161.77 |161.33 |

|mph BPM | | | | | | | | |

Prose: The raw data (after calibration correction) for blood pressures and heart rates for all subjects are listed above. All heart rate values are in beats per minute (BPM), and all blood pressure measurements are in mm Hg.

In order to assess the differences in measurements, the average values and 95% confidence intervals were calculated for each group, which can be found in the following table, Table 3.

Table 3: Average Values and 95% Confidence Intervals for Group A and Group B

| |Active |Inactive |

| | |95% CI (+/-) | |95% CI (+/-) |

| |Average | |Average | |

|Average |114.81 |15.70 |122.35 |12.86 |

|Rest Systolic | | | | |

|Average |69.38 |12.76 |75.36 |20.18 |

|Rest Diastolic | | | | |

|Average Rest MAP |84.52 |13.09 |91.02 |17.11 |

|Average |66.30 |12.88 |69.09 |13.81 |

|Rest BPM | | | | |

|Average 3.5 |120.70 |20.54 |142.31 |9.79 |

|mph Systolic | | | | |

|Average 3.5 |69.98 |8.85 |82.33 |19.13 |

|mph Diastolic | | | | |

|Average 3.5 mph MAP |86.89 |11.26 |102.33 |13.74 |

|Average 3.5 |66.81 |14.73 |81.70 |7.09 |

|mph BPM | | | | |

|Average 5.0 |141.84 |13.35 |171.93 |33.36 |

|mph Systolic | | | | |

|Average 5.0 |73.47 |7.27 |77.63 |7.29 |

|mph Diastolic | | | | |

|Average 5.0 mph MAP |96.26 |9.01 |109.07 |11.64 |

|Average 5.0 |97.68 |23.77 |135.35 |13.05 |

|mph BPM | | | | |

|Average 6.5 |128.20 |29.22 |182.47 |31.64 |

|mph Systolic | | | | |

|Average 6.5 |62.37 |11.61 |72.42 |14.65 |

|mph Diastolic | | | | |

|Average 6.5 mph MAP |84.32 |14.70 |109.10 |14.71 |

|Average 6.5 |128.02 |73.34 |153.33 |23.35 |

|mph BPM | | | | |

Prose: When comparing the average values of blood pressure for the active group (Group A) with the average values of blood pressure for the inactive group (Group B), there is a clear trend: The inactive group recorded higher resting and post-exercise values for every blood pressure and heart rate measurement at each level of physical activity. All heart rate values are in beats per minute (BPM), and all blood pressure measurements are in mm Hg.

To determine whether the observed differences between the groups were statistically significant, t-tests were conducted. The data from the tests are presented in Table 4.

Table 4: T-tests Comparing Average Blood Pressure and Heart Rate values for Group A vs. Group B

[pic]

Prose: Although Group B registered higher heart rate and blood pressure readings across the board, t-tests show that, at rest, the differences between Group A and Group B were not statistically different. However, after running at 3.5 MPH and 5.0 MPH, systolic and mean arterial blood pressures, and heart rate, were found to be significantly larger in Group B, with the exception of systolic blood pressure at the two-tail level at 3.5 mph (indicated by purple color); systolic was significant, however, at the 94% confidence interval in this case (indicated by the p value). Diastolic blood pressure was found to not be significantly different between groups and between various levels of exercise. During week 3 (speed = 6.5 MPH), systolic and mean arterial blood pressures were statistically greater in Group B; however, the comparison of heart rate were found to be anomalous, in that no significant difference was found.

The following table, Table 5, compares the percent differences of the two groups using values from Group A as the baseline.

Table 5: Percent Differences in Cardiovascular Values Between Groups

[pic]

Prose: The table above lists the percent differences in each cardiovascular measure as normalized to Group A (using Group A’s values as the baseline for comparison). All positive values indicate that the values for Group B were larger than those for Group A. At rest, values between the groups were all well within 10% of each other. As running speed increased, the differences in the cardiovascular measurements increased in most cases.

A visual representation of the data in Table 5 is presented in Figure 1.

Figure 1: Percent Differences Between Group A and Group B At Rest and Post-Exercise

[pic]

Prose: For systolic blood pressure measurements, Group B registered greater percent differences the more intense the physical activity became; a rest, the differences between the groups was about 6.57%, but after running at 6.5 mph, the difference grew to 42.32%. For diastolic and mean arterial pressures, the values for Group B were larger than those for Group A, but there appears to be no trend in terms of an increase in the percent differences; at 3.5 mph, the differences between the groups increased, but at 5.0 mph, the differences decreased, and at 6.5 mph, the gap between the groups grew even larger. For heart rate, the differences between the two groups increased at both 3.5 mph and 5.0 mph, but then dropped sharply after running at 6.5 mph.

A reliable measure of physical fitness is to determine how much various cardiovascular measures increase after physical activity; the more physically fit a person is, the less the body has to work during exercise, and the smaller the increases in blood pressure and heart rate will be.2 If this is so, Group A should register smaller increases in blood pressure and heart rate after exercise than should Group B. Data pertaining to the rates of blood pressure and heart rate elevation after exercise can be seen, for individual subjects, in Table 6 and, for Groups A and B as a whole, in Table 7.

Table 6: Percent Increase in Values Post-Exercise Compared to Rest

[pic]

Prose: Percent increases of Systolic BP, Diastolic BP, MAP, and Heart rate after running, as compared to each subject’s resting values, are shown. Negative values indicate a drop in value after running as compared to rest.

Table 7: Average Percent Increases for Groups A and B Post-exercise as Compared to Resting Values

[pic]

Prose: After running at 3.5, 5.0, and 6.5 MPH, Group B registered larger increases in EVERY cardiovascular measure than those registered by Group A.

A visual representation of the data above is shown in Figure 2.

Figure 2: Percent Increase in Cardiovascular Measures Post-Exercise

[pic]

Prose: For heart rate, systolic BP, and mean arterial BP, Group B (Inactive) registered larger increases in values post-exercise than Group A at all running speeds. For diastolic pressure, the difference in increase of values post-exercise was minimal compared to other cardiovascular measures; in fact, at 6.5 MPH, Group A (Active) recorded a larger increase from rest, albeit slight, than did Group B.

To determine if these differences in cardiovascular measurement increases are significant between the two groups, t-tests at the 95% confidence limit were conducted. Results of the tests are shown in Table 8.

Table 8: T-test Comparing Increase in Cardiovascular Measurements Post-Exercise between Group A (Active) and Group B (Inactive)

[pic]

Prose: [Note: all negative values indicate that the active group had a lower value for that measurement.] For Systolic BP, Group B registered larger increases that were statistically significant after running at 3.5 and 6.5 MPH; at 5.0 MPH, the differences were not statistically significant. For Diastolic BP, differences in blood pressure elevation between the two groups were not found to be statistically significant at all running speeds. For mean arterial pressure, differences in blood pressure elevation were found to be significantly different only after running at 3.5 MPH. For heart rate, elevation in beats per minute (BPM), was not found to be significantly different at the 95% confidence limit for any running speed; however, at 3.5 MPH, heart rate elevation was found to be statistically significant at the 94% Confidence limit on the one-tail, and at the 88% on the two-tail; at 5.0 MPH, a statistically significant difference was found on the 93% CI (one tail) and the 86% CI (two-tail).

Analysis:

The comparison of the actual values for systolic blood pressure, diastolic blood pressure, mean arterial pressure, and heart rate was analyzed by using the average value for each group at each state of exercise, as indicated in Table 3. Direct numerical comparison reveals that for each parameter, the value for the inactive group was higher than that of the active group. Although there was a trend of higher values for inactive over the active group, statistical analysis determined that not each comparison was a significant difference in values.

Hypotheses predicted that blood pressure values would be statistically significantly larger for systolic and mean arterial pressures for the inactive group over the active group at each state of exercise, but diastolic pressures would not be significantly different. Systolic pressure increases with exercise as the ventricles pumps more blood from the ventricles through the cardiovascular system to supply more oxygen to the body. However, diastolic pressure does not change significantly, because diastolic pressure is an indication of diastole, when the atria pump blood to the lungs. The mean arterial pressures indicate the actual average pressure of blood in the entire system, and therefore follows the trend of diastolic pressure increases.

As indicated in Table 4, the data at 3.5 mph, 5.0 mph, and 6.5 mph supports this hypothesis. However, at rest, the systolic values and the MAP were not significantly different. As discussed earlier, increased levels of regular exercise improve the body’s ability to deliver O2 via the cardiovascular system. The increased need for oxygen during exercise will be met more efficiently in the active individuals, which is supported by the statistical analysis of the data at 3.5 mph, 5.0 mph, and 6.5 mph, although the resting values deviate from this statement. Low resting heart rates and low blood pressures are indications of fitness. The levels of regular exercise between individuals in the different groups is not that extreme and therefore their fitness may not vary dramatically, which may be supportive of the lack of variation between resting values. Therefore, the higher levels of diastolic pressure and MAP for inactive individuals over active individuals was displayed significantly after exercise, but not at rest.

Heart rate values were predicted to be higher for the inactive group at rest and after each state of exericse. Referencing Table 4, the inactive group had significantly larger values at each level than did the inactive group. The increased heart rate and blood pressure values indicate that a history of sustained exercise will markedly reduce a subject’s need to increase work (i.e. heart rate and blood pressure) when engaging in physical activity (i.e. running).

Also as hypothesized, diastolic pressures would not be significantly different. As indicated in Table 4, this held true at the 95% confidence interval for all exercise levels, as indicated by t-tests. At no level was there a significant difference between the diastolic values of the active group and the inactive group.

Table 5 and Figure 1 represent the percent differences between the two groups values for each parameter at each state of exercise. The rest values are all within 10% of each other for both groups for systolic pressure, diastolic pressure, MAP, and heart rate. However, with increased exercise, the values percent difference of systolic pressure continue to increase from a rest difference of 6.57% to a value of 42.32% at 6.5 mph. The same trend is similar for the MAP, which increases from 7.69% at rest to 29.39% at 6.5 mph. However, there is a slight decrease in percent difference from 3.5 mph to 5.0 mph in MAP, but the values increase from 13.30% to 29.39% at the 6.5 mph state. On average, the increase in the percent difference of the inactive group over the active group support the hypotheses that the inactive group will increase heart rate and blood pressures at a faster rate. Diastolic pressures indicate no trends because the values of percent differences increase from 8.61% to 17.65%, but then decrease to 5.66%, followed by an increase to 16.11% at the most intense exercise tested. The lack of trend supports the hypothesis that diastolic pressure is least unaffected by exercise. Heart rate values show a steady increase in the percent difference between the two groups from rest to 3.5 mph to 5.0 mph (4.21% to 22.30% to 38.56%), but the difference drops to 19.77% at 6.5 mph. This drop indicates that the average values for heart rate between the two groups are closer at this level than at the previous level. Although heart rates should continue to increase with exercise, this decrease in percent difference between groups may be an indication of the genetically predetermined maximum heart rate theory, which is independent of fitness. The values support the hypothesis that a tendency toward maximum heart rate will begin to be displayed at the highest intensity level.

Table 7 lists all the blood pressure and heart rate increases that were incurred by each group during and immediately after running on a treadmill at various speeds. According to background information, individuals who are more physically fit, and exhibit a more extensive history of sustain athletic/exercise activity, would experience smaller gains in blood pressure and heart rate than those who weren’t physically active. One hypothesis made before conducting experiments on the two groups was that, for each higher level of exercise, Group B (Inactive) would register larger increases in blood pressure and heart rate after exercise than would Group A (Active). The data in Table 7 appears to corroborate this hypothesis.

The difference between Group A and Group B, in terms of their rates of blood pressure and heart rate elevation, was most evident after each group ran at 3.5 MPH. As a whole, Group A produced increases between 0.63% (for heart rate) and 5.02% (for systolic BP). In stark contrast, Group B produced increases between 9.86% (for diastolic BP) and 19.82% (for heart rate). When comparing these numbers, Group B registered increases in cardiovascular measures that were between 3 times (for systolic BP) to 19 times (for heart rate) greater than those posted by Group A. This lends very discerning evidence to the hypothesis that the history of extensive physical activity in subjects of Group A is a significant factor in decreasing the amount of work (shown through heart rate and blood pressure) needed to be done by the physically active during exercise.

The same trend exhibited by data produced at 3.5 MPH was still evident at 5.0 MPH. The cardiovascular measurements of Group A posted increases of 17.31% (for diastolic BP) to 35.06% (for systolic BP); Group B posted increases of 23.44% (for diastolic BP) to 77.58% (for heart rate). A comparison of cardiovascular measures between the groups once again yields the result that Group B recorded increases that were 1.3 times (for diastolic BP) to 2.3 times greater (for heart rate) than those produced by Group A.

At 6.5 MPH, percent increases for Group A were between 10.52% (for diastolic BP) and 72.38% (for heart rate); for Group B, between 7.05% (for diastolic BP) and 104.51% (for heart rate). In this case, Group B actually recorded a smaller increase for diastolic than did Group A (about 33% lower); for all other measurements, Group B posted increases that were 1.2 times (mean arterial BP) to 1.6 times (systolic BP) larger than those recorded by Group A.

The data presented in Table 7 may be compromised by the fact that there are incredibly large confidence intervals the correlate to the average values, especially for data obtained at 5.0 MPH and 6.5 MPH. The reasons for the large confidence intervals are that, especially on days when testing at 5.0 MPH and 6.5 MPH was done, a few test subjects reported to the testing site sick, which resulted in abnormal values for blood pressure and heart rate. For example, during week 3, Subject 3A had a resting blood pressure of 71.53 mm Hg, and a post-exercise blood pressure of 90.16. Another example is Subject 1A, who had a recorded resting heart rate of 66.77 BPM, and then had a recorded heart rate after running at 6.5 MPH of 65. 58. Such anomalies in the data could not be accounted for prior to testing, and these values may have severely skewed the data. In addition, during the third week (running at 6.5 MPH), the number of trials conducted was cut to two (from the usual three), because test subjects felt they would be unable to complete three trials successfully. As a result, this significantly inflated the 95% confidence intervals for that week. While the data does show trends that may support the hypotheses made prior to testing, the presence of large 95% confidence intervals does not allow for any statistically significant conclusions to be made.

Figure 2 is a graphical representation of Table 7; as previously stated, in general, Group B registered larger increases in all cardiovascular measurements except diastolic blood pressure, for all running speeds. This indicates that Group B, as a whole, must do more work during exercise, regardless of intensity, as reflected by the larger gains in heart rate and blood pressure. What should also be noted from the figure is that, in terms of sensitivity, heart rate seems to be the cardiovascular measure most sensitive (i.e exhibits the most change) to exercise; this trend was exhibited in both groups, and increases in this measurement greatly eclipsed the changes in all other cardiovascular measurements. Following heart rate in sensitivity are systolic blood pressure, mean arterial pressure, and diastolic blood pressure, respectively; these trends were also supported by both groups.

Table 8 is a summary of t-tests comparing between groups the increases in each cardiovascular measurement after exercise. Increases in diastolic pressure were not found to be significantly different between the two groups, for all running speeds tested. Diastolic pressure was determined to be the least sensitive of the cardiovascular measurements, and the t-tests support this conjecture. At 3.5 MPH, increases in systolic BP and mean arterial pressure were found to be statistically larger in Group B, as expected; however, increases in heart rate were not found to be statistically different between the groups. However, although heart rate was not found to be significant different by t-tests (i.e. 95% confidence), a p value of 0.06 indicates that it is significant at the 94% confidence. Unexpected results were displayed at 5.0 mph. The systolic and mean arterial percent differences were not significantly different between the two groups, and the p values of 0.26 and 0.33 for systolic and MAP, respectively, indicate relatively low confidence intervals of 74% and 67%, respectively. However, at 6.5 mph t-tests indicate systolic pressure is significantly different at 95% confidence, although MAP values do not follow this trend (p value of 0.20), which was unexpected. The heart rate percent differences at 6.5 mph also do not display any significant difference between groups (p value of 0.21). However, this trend was expected at 6.5 mph due to the subjects beginning to approach their maximum heart rate as discussed earlier.

Inspection of Table 2 (raw data values for individual subjects) and Table 6 (percent increase from rest for each state for individual subjects) indicates a few individual values that do not follow the same trend as the rest of the data. For example, in Table 2, Subject 2A’s resting values for blood pressure were significantly less than for the earlier two weeks. Also, her heart rate and blood pressure increases were not as large as the week before at a less intense physical stimulation. However, prior to testing, the subject indicated that she came down with a bad cold over the weekend before. Her illness may have skewed her values to be unreliable as indication of not following the trend of the rest of the subjects. Also, Table 6 indicates several negative percent increases, indicating a decrease in a parameter. Many of these negative percent increases arise from diastolic pressure differences, which were hypothesized to indicate no trends throughout the experiment. As a result, these negative values were included in analysis. During week 1, Subject 1A displayed a small decrease in heart rate (-2.71%) from rest at the 3.5 mph exercise state. However, this was the least intense exercise level, and the subject was in the active group; the small increase was concluded to be insignificant because the subject is considered “active” and the walk at 3.5 mph was expected to not affect his cardiovascular parameters greatly. The final value that gave concern was the –1.78% increase from rest for Subject 1A during exercise at 6.5 mph (indicating a DECREASE of 1.78% in heart rate). Given that this was the most intense exercise level, it was expected that heart rate would increase significantly. However, Subject 1A did suffer from a pulled calf muscle the week before experimentation at 6.5 mph. He was tested later in the week than the other subjects, and was still recovering from the injury. As a result, this value is not a valid representation of the trend he might have experienced under normal circumstances.

Conclusions:

1. On average, individuals who participate in aerobic activities will lower their expected systolic blood pressure and heart rates after low to moderate exercise. Values for the experiment showed that systolic blood pressures were lower for the active group by 6.57%, 17.91%, and 21.22% for rest, 3.5 mph, and 5.0 mph, respectively. For heart rate this percent difference was 4.21%, 22.30%, and 38.56% for for rest, 3.5 mph, and 5.0 mph, respectively.

2. Inactive individuals will experience greater rates of elevation in systolic blood pressure and heart rate while exercising than their active counterparts. For systolic blood pressures, the inactive group indicated an increase of 13.11% more than the increase of the active group, on average. There was an average increase of 31.54% more for the inactive group than the active group for heart rate values.

3. In spite of physically active histories, individuals tend to display a maximum heart rate after intense exercise that is determined by genetic factors; no relationship between the heart rates of inactive and inactive individuals will be present. At 6.5 mph, the heart rate values between groups displayed a p value of 0.35, whereas at 3.5 mph and 5.0 mph the p values were 0.04 and 0.01, respectively, indicating that the significant difference between groups does not apply after intense exercise.

Recommendations:

Upon completion of the project, a few recommendations have been devised to improve experimentation and results. First of all, all trials for a given subject should be conducted on the same day. This will eliminate the source of error of slight variations in resting blood pressures and heart rates for individual subjects. Daily resting values varied insignificantly for most subjects week-to-week. However, in some cases, individual subjects came down with a cold, or injured themselves over the weekend prior to one of the Mondays of testing. As a result, their resting values for that day could not be compared with resting values from the first week of testing. If all trials were conducted in one day, the uncertainty here would be eliminated.

Secondly, all variables (i.e. height, weight, gender, etc.) need to be held constant for each group, isolating only differences in level of physical activity. This will eliminate the possibility of variations between groups being the result of anything other than physical activity differences. Due to the resources, time frame, and subjects available in lab, these parameters were not possible. However, in the event of a larger and less varied (other than physical activity) sample pool, subjects could be chose to reduce the effects of other parameters affecting heart rate and blood pressure values.

Another recommendation would be to measure the level of activity based on an increase in heart rate (i.e. moderate exercise for a 50% increase in heart rate), instead of based on a speed to run on the treadmill. This approach would require substantial time to study and evaluate each subject in order to determine at what speed and what physical activity he or she would display the desired increases in heart rate prior to testing. However, it would also eliminate the differences of abilities between subjects who could not physically run at speeds or distances that other subjects were able to tolerate. As a result, some subjects may have overexerted themselves in this experiment, whereas those more accustomed to the exercise may not have reached their maximum capabilities.

References:

1BioPac Pro( manual.

2Berne, Robert M.; Levy, Matthew N, eds. Physiology, 4th ed.. Mosby Inc.: St. Louis, MO, 1998.

3Medline Plus. Blood Pressure.

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4Wilmore JH. Stanforth PR. Gagnon J. Rice T. Mandel S. Leon AS. Rao DC. Skinner JS. Bouchard C. "Heart rate and blood pressure changes with endurance training: the HERITAGE Family Study." Medicine & Science in Sports & Exercise. 33(1):107-16, 2001 Jan.

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