Pulse Rate Lab Report
The effect of exercise on cardiovascular functions such as pulse rate, pulse lag, the PT interval, the TP interval, systolic, and diastolic blood pressure is noticeable after running down the steps of Long Hall and back up to the third floor. As Table 1 shows, the data support the initial hypothesis that the pulse rate will increase, the pulse lag will decrease, both the PT and TP intervals will decrease, and the systolic and diastolic blood pressure will increase. The pulse rate mean before exercise was about 78 beats per minute, also shown in Table 1, which is consistent with scientific literature stating that the resting heart beat of adults should be between sixty and a hundred beats per minute, as discussed in the introduction. The pulse rate after exercise was almost 100 beats per minute, which is significantly higher than the resting heart rate. The chi-square value was 6.368 with a p-value of 0.0116. Since the p-value is less than the alpha level of 0.05, we reject the null hypothesis that there is no different between the pulse rate before and after exercise. A similar pattern exists for blood pressure.
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The blood pressure before exercise was about 11678and the blood pressure after exercise was about 14793according to Table 1. The chi-square value for the systolic and diastolic blood pressures are 11.1 and 8, respectively, with p-values of 0.00085 and 0.0047, respectively. Since both p-values are less than the alpha level of 0.05, we reject the null hypothesis that no difference exists between the before and after treatments of exercise. The main reason the heart rate and blood pressure increase is because of the energy demand exercise requires of the body. The muscles are consuming oxygen for energy via anaerobic or aerobic respiration and depositing carbon dioxide in the blood at a higher rate during exercise. For example, when a track athlete is running the mile race, they are using both aerobic and anaerobic respiration to consume oxygen in the process of cellular respiration and also produce lactic acid when not enough oxygen is available in the cells. Through respiration and fermentation, energy in the form of ATP is produced for the body so that the athlete can keep pumping their arms and moving their legs toward the finish line. Thus, the heart must pump quicker so that more oxygen is available for the muscles to consume and so that the diffusion of gases can occur in the lungs, where carbon dioxide diffuses out of cells and oxygen is replenished (BBC, 2014).
Because the heart is beating more rapidly to supply the muscles with oxygen, blood pressure also increases due to exercise.
This increase results from the heart also pumping with greater intensity, increasing the volume of the blood. As a result, the amount of oxygen flowing to the body during exercise also increases. An increase in blood volume is analogous to an increase in blood pressure. Pescatello, Fargo, et al (1991) found that men who exercised regularly lowered their blood pressure, preventing and mediating hypertension. Because the heart is pumping more blood at a greater frequency during exercise, the muscle is essentially strengthening, getting more efficient, so that at rest, it functions better. Thus, exercise causes immediate increases in pulse rate and blood pressure, but causes a lowering in both when the body returns to a resting
condition. Table 1 also displays how the pulse lag, PT time interval, and TP time interval all decreased as a result of running up and down the stairs in Long Hall. Before exercise the pulse lag was about 0.289 seconds, the PT interval was about 0.501 seconds, and the TP interval was about 0.322 seconds. After exercise, the pulse lag was 0.268 seconds, the PT interval was about 0.406 seconds, and the TP interval was about 0.317 seconds. Clearly the data show a decrease in each category, with chi-square values of 5.556, 5.556, and 4 for pulse lag, PT interval, and TP interval, respectively. The resultant P-values were all less than the alpha level of 0.05 at 0.018, 0.018, and 0.0455, respectively. Therefore, we reject the null hypothesis that there is not a difference between the pulse lag, PT interval, and TP interval before and after exercise. In fact, there is a difference which is observed through the ECG data and graphs.
Exercise causes the appearance of the ECG to differ from the resting greatly because the frequency and force at which the heart contracts changes, which are the same factors that affect the pulse rate and blood pressure as formerly explained. The TP interval is smaller after exercise because the heart is not “resting” as much between beats (White, Sharma, 2010). The heart must rapidly move from the repolarization of the ventricles to the depolarization of the atria because the heart must supply as much oxygen as possible to the muscles in the shortest amount of time. Likewise, the pulse lag decreases because the heart does not want the appearance of blood in the finger after the ventricles contract to take a long time because that would mean the muscles are not getting oxygen quickly enough.
The PT interval decreases for a similar but different explanation. As discussed in the introduction, the PT interval is the amount of time from the atria contractions to the ventricular contractions. Because the heart wants to send a large volume of blood at a higher frequency during exercise, the electrical signals will fire more rapidly through the movement of ions across cell membranes causing the potentiation of action potentials. As a result, the heart will contract quicker because more action potentials are being sent; in other words, the SA node, the pacemaker, will increase the frequency of action potentials firing through the heart during exercise so that the heart will beat quicker. This change is observed on the ECG and is why the PT interval is shorter after exercise than it was before exercise. Additionally, exercise may aggravate pre-existing heart conditions and magnify their existence on the ECG such as patients with Brugada Syndrome, who experience ventricular arrhythmia during exercise, often causing wider QRS complexes (Ahmin, Groot, et al., 2009). Otherwise, most changes in the ECG before and after exercise are normal for a healthy individual.
A major weakness in this study is the lack of control we had over the control variables. The amount of caffeine, the hydration levels, drug use, and the amount of consumed carbohydrates were all reported to be kept constant. The use of a paired chi-square test also minimizes bias because each individual’s results are compared only to themselves. However, if the controls were not constant, they could alter how much an individual’s data changes from before to after exercise. For example, if someone drank a large glass of water before they exercised, their heart would function more efficiently. The difference between their before and after measurements in all categories would have a smaller margin than if they were dehydrated. Our collection of data and the reliability of the control variables is based on information each member of the lab reported (i.e. everyone reported that they did not drink caffeine that day). However, someone could have consumed caffeine, but been too shy to admit it, so that variable was not kept constant. The other control variables have the same dilemma.
To improve this experiment in the future, a key concept would be to repeat the process at least three times. With the repetition, the results could be compared between each round of data so that if not all control variables were kept constant each time, they would not influence the overall larger theme in the data. Additionally, if this experiment were held in serious conditions, where our section started lab at least twelve hours before we started the experiment, we could make sure everyone ate the same thing for meals, ate the same amount, drank the same amount of water, and got the same amount of sleep. Obviously, within the restrictions of college, this would not be possible but it would yield more reliable results. Overall, this lab was kept as constant as possible for college students and the results displayed patterns that are consistent with scientific literature so the weaknesses did not affect the results in a major way. In the future, more experiments similar to this one will most likely show the effects exercise has on cardiovascular functioning and how everyone should run up the stairs more often.
The blood pressure before exercise was about 11678and the blood pressure after exercise was about 14793according to Table 1. The chi-square value for the systolic and diastolic blood pressures are 11.1 and 8, respectively, with p-values of 0.00085 and 0.0047, respectively. Since both p-values are less than the alpha level of 0.05, we reject the null hypothesis that no difference exists between the before and after treatments of exercise. The main reason the heart rate and blood pressure increase is because of the energy demand exercise requires of the body. The muscles are consuming oxygen for energy via anaerobic or aerobic respiration and depositing carbon dioxide in the blood at a higher rate during exercise. For example, when a track athlete is running the mile race, they are using both aerobic and anaerobic respiration to consume oxygen in the process of cellular respiration and also produce lactic acid when not enough oxygen is available in the cells. Through respiration and fermentation, energy in the form of ATP is produced for the body so that the athlete can keep pumping their arms and moving their legs toward the finish line. Thus, the heart must pump quicker so that more oxygen is available for the muscles to consume and so that the diffusion of gases can occur in the lungs, where carbon dioxide diffuses out of cells and oxygen is replenished (BBC, 2014).
Because the heart is beating more rapidly to supply the muscles with oxygen, blood pressure also increases due to exercise.
This increase results from the heart also pumping with greater intensity, increasing the volume of the blood. As a result, the amount of oxygen flowing to the body during exercise also increases. An increase in blood volume is analogous to an increase in blood pressure. Pescatello, Fargo, et al (1991) found that men who exercised regularly lowered their blood pressure, preventing and mediating hypertension. Because the heart is pumping more blood at a greater frequency during exercise, the muscle is essentially strengthening, getting more efficient, so that at rest, it functions better. Thus, exercise causes immediate increases in pulse rate and blood pressure, but causes a lowering in both when the body returns to a resting
condition. Table 1 also displays how the pulse lag, PT time interval, and TP time interval all decreased as a result of running up and down the stairs in Long Hall. Before exercise the pulse lag was about 0.289 seconds, the PT interval was about 0.501 seconds, and the TP interval was about 0.322 seconds. After exercise, the pulse lag was 0.268 seconds, the PT interval was about 0.406 seconds, and the TP interval was about 0.317 seconds. Clearly the data show a decrease in each category, with chi-square values of 5.556, 5.556, and 4 for pulse lag, PT interval, and TP interval, respectively. The resultant P-values were all less than the alpha level of 0.05 at 0.018, 0.018, and 0.0455, respectively. Therefore, we reject the null hypothesis that there is not a difference between the pulse lag, PT interval, and TP interval before and after exercise. In fact, there is a difference which is observed through the ECG data and graphs.
Exercise causes the appearance of the ECG to differ from the resting greatly because the frequency and force at which the heart contracts changes, which are the same factors that affect the pulse rate and blood pressure as formerly explained. The TP interval is smaller after exercise because the heart is not “resting” as much between beats (White, Sharma, 2010). The heart must rapidly move from the repolarization of the ventricles to the depolarization of the atria because the heart must supply as much oxygen as possible to the muscles in the shortest amount of time. Likewise, the pulse lag decreases because the heart does not want the appearance of blood in the finger after the ventricles contract to take a long time because that would mean the muscles are not getting oxygen quickly enough.
The PT interval decreases for a similar but different explanation. As discussed in the introduction, the PT interval is the amount of time from the atria contractions to the ventricular contractions. Because the heart wants to send a large volume of blood at a higher frequency during exercise, the electrical signals will fire more rapidly through the movement of ions across cell membranes causing the potentiation of action potentials. As a result, the heart will contract quicker because more action potentials are being sent; in other words, the SA node, the pacemaker, will increase the frequency of action potentials firing through the heart during exercise so that the heart will beat quicker. This change is observed on the ECG and is why the PT interval is shorter after exercise than it was before exercise. Additionally, exercise may aggravate pre-existing heart conditions and magnify their existence on the ECG such as patients with Brugada Syndrome, who experience ventricular arrhythmia during exercise, often causing wider QRS complexes (Ahmin, Groot, et al., 2009). Otherwise, most changes in the ECG before and after exercise are normal for a healthy individual.
A major weakness in this study is the lack of control we had over the control variables. The amount of caffeine, the hydration levels, drug use, and the amount of consumed carbohydrates were all reported to be kept constant. The use of a paired chi-square test also minimizes bias because each individual’s results are compared only to themselves. However, if the controls were not constant, they could alter how much an individual’s data changes from before to after exercise. For example, if someone drank a large glass of water before they exercised, their heart would function more efficiently. The difference between their before and after measurements in all categories would have a smaller margin than if they were dehydrated. Our collection of data and the reliability of the control variables is based on information each member of the lab reported (i.e. everyone reported that they did not drink caffeine that day). However, someone could have consumed caffeine, but been too shy to admit it, so that variable was not kept constant. The other control variables have the same dilemma.
To improve this experiment in the future, a key concept would be to repeat the process at least three times. With the repetition, the results could be compared between each round of data so that if not all control variables were kept constant each time, they would not influence the overall larger theme in the data. Additionally, if this experiment were held in serious conditions, where our section started lab at least twelve hours before we started the experiment, we could make sure everyone ate the same thing for meals, ate the same amount, drank the same amount of water, and got the same amount of sleep. Obviously, within the restrictions of college, this would not be possible but it would yield more reliable results. Overall, this lab was kept as constant as possible for college students and the results displayed patterns that are consistent with scientific literature so the weaknesses did not affect the results in a major way. In the future, more experiments similar to this one will most likely show the effects exercise has on cardiovascular functioning and how everyone should run up the stairs more often.