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REACH Inquiry Lesson: How does particulate air pollution affect the cardiovascular system?
Grade/ Grade Band: 9-12 Topic: Par ticulate air pollution and cardiovascular health.
Lesson Number: 2 (in a series of 3 lessons)
Lesson Description: Cardiovascular disease (including heart disease and stroke) accounts for one in every three deaths and is the leading cause of mortality in adults in the U.S. Health care costs for these maladies is nearly $1 billion per day or one in every six health care dollars spent.4 The importance of maintaining cardiovascular health is not just a personal health issue; it is a population health issue. In this lesson, students will examine cardiovascular health as a popula-tion health issue in the United States; investigate cardiovascular wellness as a function of heart rate recovery; and explore the effects of particulate air pollution exposure on cardiovascular health. The lesson requires two class peri-ods.
Learning Targets – students will be able to: Discuss how poor individual cardiovascular health choices can contribute to cardiovascular health as a popula-
tion health issue. Measure their heart rate recovery and explain how this measurement is an indicator of cardiovascular health. Describe the effects of particulate air pollution on cardiovascular health as measured by arterial stiffness. Inclusion of American Indian Content: Cardiovascular disease affects American Indians and Alaska Natives (AI/AN) at disproportionate rates:1 Mortality from heart disease is 20 percent greater among Native populations than among other U.S. ethnic
groups, and is 14 percent greater from stroke. AI/AN people die from heart disease at younger ages than other racial groups in the U.S. Thirty-six percent of
those who die from heart disease die prior to age 65. While cardiovascular disease morbidity and mortality are higher in native populations, the physiologic
measures in these groups are similar to all other people. Narrative / Background Information Prior Student Knowledge: Students should know the main components of the cardiovascular system: the heart, the pump; the blood, the
fluid being pumped throughout the body; and the blood vessels (arteries, veins, and capillaries), the tubes through which the blood is pumped. Arteries are high pressure delivery vessels where blood pressure is typical-ly measured; veins are lower pressure return vessels where blood is typically drawn; and capillaries are the site of nutrient and gas exchange between the blood and tissues.
Students should know the primary functions of the cardiovascular system: transport oxygen and nutrients to the cells; transport carbon dioxide and metabolic wastes away from the cells; and assist in the regulation of internal body temperature.
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NGSS Performance Expectations:
HS-LS1-2: Develop and use a model to illustrate the hierarchical organization of interacting systems that pro-vide specific functions within multicellular organisms. An example of an interacting system could be an artery depending on the proper function of elastic tissue of smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.
HS-LS1-3: Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeo-stasis. An example of investigation could include heart rate response to exercise.
Science & Engineering Practices: Analyzing and interpreting data Using mathematics and compu-
tational thinking Engaging in argument from evi-
dence
Disciplinary Core Ideas: LS1: Molecules to organisms, struc-tures and processes
Crosscutting Concepts: Cause and effect Systems and system models Stability and change
Possible Preconceptions/Misconceptions:8
If you have heart disease, you need to take it easy. Being sedentary can lead to blood clots and a decline in
overall physical condition. Exercise helps to strengthen heart muscle, lower heart rate at rest, lower heart rate for a given amount of physical work (e.g., jogging 4 mph), and improve the control of blood flow in all instanc-es.
Higher blood pressure is expected as you age. Blood pressure does tend to rise with age but that does not mean that it is good for you or should be accepted. In most individuals, artery walls stiffen with age forcing the heart to work harder. Blood pressure can be managed with exercise and medication.
Cardiovascular disease risks can be lowered by taking vitamins and supplements. The American Heart Associa-tion has concluded there is no scientific evidence showing supplements prevent or treat cardiovascular disease, while a balanced, nutrient dense diet is shown to preserve cardiovascular health.
Heart disease is generally a man’s problem. Since 1984, more women than men have died each year from heart diseases. Heart disease is also the leading cause of death in women over age 65. By retirement age, 70% of men and women have some form of cardiovascular disease.
If you have cardiovascular disease, you should not consume fats. Unsaturated fats in vegetable oils and other foods are beneficial and some fats such as omega-3 fatty acids can lower the risk of heart disease.
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LESSON PLAN – 5-E Model
ENGAGE: How do you measure heart rate recovery?
The purpose of this activity is to use heart rate recovery as a framework to introduce the topic of cardiovascular disease and discuss its implications as a significant population health problem. Heart rate recovery refers to how quickly the heart rate decreases after exercise. It is used as an indicator of overall cardiovascular fitness. An important point of this activity is how individual choices regarding cardiovascular health and fitness impact the widespread population health problem of cardiovascular disease. Review the primary risk factors for cardi-ovascular disease that are covered in the Background section: tobacco use, a sedentary lifestyle, high blood pressure, and high cholesterol. Time required = 1 class period.
Students will be divided into groups of two, three, or four. One of the group members will act as the volunteer. The research volunteer should be healthy and dressed in a manner where they are able to perform several minutes of moderate intensity exercise. There needs to be enough space for the volunteers to do moderate exer-cise such as jumping jacks, running in place, burpees (see teacher materials), etc. It may be easier for students to move to a larger space such as a gym or multipurpose room. Students will generally need to exercise for 3 – 5 minutes depending on the intensity of the exercise.
Students need some type of timing device and to be able to measure heart rate using pulse points at either the neck or the wrist.
Vocabulary:
Cardiovascular System: the system that transpor ts blood through the body. Specifically, the blood, the heart, and the blood vessels – arteries, veins, and capillaries.
Cardiovascular Disease: generally refers to conditions that nar row or block blood vessels which can lead to heart attack, chest pain, and stroke.
Homeostasis: any self-regulating process by which organisms tend to maintain physiological stability while adjusting to conditions that are optimal for survival.
Heart Rate Recovery: how quickly the hear t rate recovers, from sympathetic to parasympathetic influ-ences, after periods of exercise. Used as an indicator of overall cardiovascular health and fitness, where the sooner the heart rate returns to baseline, the healthier someone is likely to be.
Parasympathetic Nervous System: the automated par t of the nervous system that controls digestive sys-tem and the cardiovascular system at rest. Specifically, the parasympathetic nervous system slows heart rate and increases intestinal and gland activity following a meal.
Sympathetic Nervous System: the automated par t of the nervous system that mediates the neuronal and hormonal responses to a stressful situation, commonly known to mediate the fight or flight response.
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EXPLORE: How does exposure to par ticulate air pollution affect the cardiovascular system? The purpose of this activity to determine if there is a cardiovascular response to increased particulate air pollu-
tion exposure. The data is adapted from the pioneering research study, Respiratory and cardiovascular respons-es to walking down a traffic-polluted road compared with walking in a traffic-free area in participants aged 60 years and older with chronic lung or heart disease and age-matched healthy controls: a randomized, crossover study, conducted by Drs. Rudy Sinharay and Jicheng Gong from Imperial College, London.10 The study is sum-marized in the background section at the beginning of the explore activity. Time required = 1 class period.
This activity uses pulse wave velocity data to monitor cardiovascular response to particulate air pollution expo-sure. This first 25 seconds of this YouTube video, http://bit.ly/CalcPulseWave, effectively animates how pulse wave velocity is calculated. This 16 second YouTube video, http://bit.ly/AnimatePulseWave, animates the dif-ference of a pulse wave moving through a less flexible and a healthier, more flexible dorsal aorta.
Data in Table 1 was adapted from data that was graphed in the original study. The adaptation was made to give students experience in graphing and graph interpretation.
Students can use web resources to answer questions 1 and 2. If web resources are not available, the material can be delivered directly. It is important that students understand that increases in pulse wave velocity indicate a negative cardiovascular response to a stimulus, in this case, exposure to increased air particulate levels.
Regarding question 3, hypothesis/prediction, emphasize that students defend their prediction. Additionally, stress to students that a hypothesis does not have to be supported by the data at the end of the study, but it should be well reasoned when it is formulated at the start of the investigation.
EXPLAIN: The purpose of explain questions 4 and 5 is to demonstrate to students that exposure to higher levels of particu-
late air pollution while doing moderate exercise causes a corresponding negative response by the cardiovascu-lar system in the form of increased pulse wave velocities. Question 5 emphasizes that air particulate exposure not only negates the cardiovascular benefits of moderate exercise, it can reverse them. It is important that stu-dents make references to the data to support their responses.
Question 6 asks students to apply their understanding of air particulate exposure and cardiovascular system response to a novel situation. If moderate exercise in an environment of elevated particulate air pollution levels causes a negative cardiovascular response, then there is no reason to think that moderate exercise in an environ-ment of significantly higher particulate air pollution levels would cause any less of a cardiovascular response and would likely cause a more drastic response. For instance, Baxter found that firefighters’ prolonged expo-sure to high particulate air pollution levels did indeed lead to a higher incidence of cardiovascular disease.2
The conclusion requires that students restate their hypothesis; make a statement in regards to the validity of the hypothesis; and use references to the data to defend the validity statement.
Vocabulary:
1. Chronic Obstructive Pulmonary Disorder (COPD): a group of progressive lung diseases including em-
physema, chronic bronchitis, and non-reversible or refractory asthma (does not respond to treatment). COPD is characterized by breathlessness and is currently treatable but incurable.
2. Ischaemic heart disease: a condition caused by narrowed hear t ar ter ies, also referred to as coronary ar -tery disease and coronary heart disease.
3. Pulse wave velocity: a measure of the rate at which pressure waves move down a blood vessel, from the heart to the limbs. It is a measure of arterial stiffness, in that increased arterial stiffness causes higher pulse wave velocities. Pulse wave velocity is a reliable predictor for cardiovascular morbidity and mortality.
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EVALUATE:
The important formative questions associated with this activity are: What is heart rate recovery and why is it an indicator of cardiovascular health and fitness? How do individual choices regarding cardiovascular health impact cardiovascular health as a population health
issue? How does exposure to elevated particulate air pollution levels affect the cardiovascular system? How can this
effect be measured? There is a summative assessment in the Evaluate activity that addresses the above questions in a more formal man-ner. Question 3 asks students to apply what they have learned about the cardiovascular system’s response to elevated air particulate pollution levels to the new concept of augmentation index as a measure of cardiovascular health. Aug-mentation index is described, although not by name, in the YouTube video - http://bit.ly/AugIndex. The questions in the summative assessment can be used as an end of activity quiz or the questions can be used individually as exit tickets, bell activities, or as a series of short, one question quizzes.
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Resources/References: 1. American Indian and Alaska Native Heart Disease and Stroke Fact Sheet|Data & Statistics|DHDSP|CDC.
(2016). Retrieved from https://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_aian.htm 2. Baxter, C., Hoffman, J., Knipp, M., Reponen, T., & Haynes, E. (2014). Exposure of Firefighters to Particulates
and Polycyclic Aromatic Hydrocarbons. Journal Of Occupational And Environmental Hygiene, 11(7), D85-D91. doi: 10.1080/15459624.2014.890286
3. Guilkey, J. P., Overstreeet, M., & Mahon, A. D. (n.d.). Heart Rate Recovery from Submaximal Exercise in Boys
and... : Medicine & Science in Sports & Exercise. Retrieved from https://journals.lww.com/acsm-msse/fulltext/2003/12000/Heart_Rate_Recovery_from_Submaximal_Exercise_in.21.aspx#
4. Heart Disease and Stroke Cost America Nearly $1 Billion a Day in Medical Costs, Lost Productivity. (2015, April
29). Retrieved from https://www.cdcfoundation.org/pr/2015/heart-disease-and-stroke-cost-america-nearly-1-billion-day-medical-costs-lost-productivity
5. Heart Rate Recovery - How to Measure Yours • MYZONE | Group Heart Rate Tracking | Heart Rate Zones. (2017, October 12). Retrieved from https://myzone.org/blog/trainers/heart-rate-recovery/
6. Improve Heart Health by Knowing Your Recovery Heart Rate. (2019, March 07). Retrieved from https://www.enhancedmedicalcare.com/2013/01/20/improve-heart-health-by-knowing-your-recovery-heart-rate/
7. Ischemic Heart Disease | National Heart, Lung, and Blood Institute (NHLBI). (2019). Retrieved from https://www.nhlbi.nih.gov/health-topics/ischemic-heart-disease
8. Publishing, H. 5 myths about heart disease - Harvard Health. Retrieved from https://www.health.harvard.edu/heart-health/5-myths-about-heart-disease
9. Pulse Wave Velocity. (2019). Retrieved from https://www.datasci.com/solutions/cardiovascular/pulse-wave-velocity-(pwv)
10. Sinharay, R., Gong, J., Barratt, B., Ohman-Strickland, P., Ernst, S., & Kelly, F. et al. (2017). Respiratory and cardiovascular responses to walking down a traffic-polluted road compared with walking in a traffic-free area in participants aged 60 years and older with chronic lung or heart disease and age-matched healthy controls: a randomised, crossover study. Retrieved from https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)32643-0/fulltext
11. Thurston, G., & Newman, J. (2018). Walking to a pathway for cardiovascular effects of air pollution. The Lan-cet, 391(10118), 291-292. doi: 10.1016/s0140-6736(17)33078-7
12. What is COPD? | Signs and Symptoms. (2019). Retrieved from https://www.copdfoundation.org/What-is-COPD/Understanding-COPD/What-is-COPD.aspx
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Teacher’s Notes:
Materials Required for Lesson/Activity
Copies of Engage, Explore/Explain, and Evaluate activities – 1 per student Engage Activity: Timers for measuring pulse rate – 1 per heart rate recovery research group
Explore/Explain: Straight edge for graphing Table 1 data – 1 per student. Colored pencils or pens – 2 per student.
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Name
Date Class
“We cannot change what we are not aware of, and once we are aware, we cannot help but change?”
Sheryl Sandberg
Chief Operating Officer, Facebook
Engage: How do you measure heart rate recovery?
Background: Cardiovascular disease (hear t disease and stroke) is the number one killer of adults in the United States. Nearly 800,000 people die of cardiovascular disease each year; that is one in every three deaths. Americans suffer 1.5 million heart attacks and strokes each year. The most important risk factors for cardiovascular disease include tobacco use, a sedentary lifestyle, high blood pressure, and high cholesterol. As risk factors accumulate (e.g., inactivity + high blood pressure), there is a cumulatively greater increase in the risk for cardiovascular disease. About half of Americans (47%) have at least one of these risk factors. In addition, about 1 in 3 adults or approximately 86 million people have at least one form of cardiovascular disease. Cardiovascular disease costs the United States $320 billion a year in treatment, medication, and lost productivity. This represents one in every six health care dollars spent. It is estimated that this cost will rise to $818 billion and lost productivity to $275 billion by 2030.
1. What are the main components of the cardiovascular system?
2. What are the primary functions of the cardiovascular system?
3. The responsibility for the health of your cardiovascular system is largely an individual choice. Explain how that individual choice impacts the larger population health issue of cardiovascular disease in the United States.
Human Heart
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What is heart rate recovery?
Heart rate recovery refers to the speed at which your heart rate returns to the baseline pulse rate after a period of exercise. It is a useful indicator of overall cardiovascular health in that healthier individuals experience a more rapid return to the resting heart rate. When you exercise, the sympathetic nervous sys-tem (fight or flight mode) activates and the parasympathetic nervous system (rest and digest mode) with-draws. This causes an increased heart rate, increased blood pressure, and decreased blood flow to the di-gestive organs. When you stop exercising, the opposite process occurs: a decreased heart rate and a re-turn of the body to homeostasis or steady state. Studies show the speed at which our heart rate declines after exercise is attributed to how quickly the nervous system shifts from sympathetic to parasympathet-ic. Delayed or impaired parasympathetic activation is an important indicator of cardiovascular health and fitness. Heart rate recovery is slowed in patients suffering from cardiovascular disease and is accelerated in well trained athletes. In essence, the less efficient your heart is, the more it has to beat (beats per mi-nute) to move blood through the body to sustain a given amount of work (e.g. jogging 4 mph). Regular cardiovascular exercise strengthens the heart muscle allowing your heart to increase the volume of blood it pumps with every beat. Heart rate recovery is one method used to measure cardiac efficiency.
Materials:
Timer Space to do moderate exercise
4. You will be working in groups of two, three, or four. Select a volunteer from the group. The volunteer should be healthy and not suffering from any respiratory, cardiovascular, or musculoskeletal condi-tions. The volunteer should also be dressed in a manner that facilitates a brief period of moderate ex-ercise.
5. Measuring heart rate recovery requires the volunteer to do moderate exercise until they reach their tar-get heart rate. The target heart rate is approximately 70% of the estimated maximum heart rate (220-age). Example: if you are 15 years old, your target heart rate would be (220 – 15) x 0.70 = 144 bpm (beats per minute). Record your target heart rate in the space below and in Table 1.
Target Heart Rate = ___________
6. Your instructor will demonstrate how to measure your heart rate by finding a pulse point (either on the neck or the wrist). Count the number of heartbeats you feel in 15 seconds then multiply that number by four to get your resting heart rate (beats per minute). Record your resting heart rate in the space below and in Table 1. Resting heart rate is also an indicator of cardiac efficiency. Efficient and fit hearts tend to have lower resting heart rates.
Resting Heart Rate = __________
7. To measure your heart rate recovery, you have to perform moderate exercise until your heart rate reaches the target heart rate you recorded in step 5. You can run in place, jog, do jumping jacks, jump rope, go up and down stairs, do burpees… time and space will dictate the types of available exercise.
Diagram of an EKG
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You will generally have to exercise for 3 to 5 minutes to reach your target heart rate. Check your heart rate using the steps outlined in step 6 above. As soon as you have reached your target heart, stop exercising, sit down, and measure your heart rate. Record this information in Table 1 below. Rest for two minutes then measure your heart again. Record this information in Table 1. To calculate your heart rate recovery, subtract your heart rate after two minutes rest from your heart rate immediately after exercise. Record this value in Table 1.
Table 1: Calculating Heart Rate Recovery
Volunteer Initials
Age Gender Fitness Level* 1, 2, 3
Resting Heart Rate
Target Heart Rate
Heart Rate After Exercise-A
Heart Rate, at 2 minutes-B
Heart Rate Recovery: A - B
* 1 = Competitive athlete in training, 2 = exercise three or more times per week, 3 = average fitness.
Heart rate recovery is generally defined in terms of your biological age (e.g. the relative fitness or effi-ciency of your heart) compared to your calendar age. Below are some comparative guide-lines. Check the description that best matches the data generated by the research volunteer:
*Biological age (also referred to physiological age) refers to how old a person seems to be from a physiological perspective. e.g. Assume you are a 15 year old and your heart rate is 142 bpm immediately after exercise. Two minutes after exercise, your heart rate is 123 bpm. Your heart rate recovery would be 142 bpm – 123 bpm = 19. According to the above chart, your
biological age is older than a typical 15 year old. In other words, your heart reacts like a heart from someone older than 15.
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8. Confer with several other groups and record the data from their research volunteer in Table 1.
9. Refer to the data in Table 1 to completely and concisely address the following questions. Be sure to defend your responses with examples from the data.
a) Does there appear to be a relationship between age and heart rate recovery?
b) Does there appear to be a relationship between gender and heart rate recovery?
c) Does there appear to be a relationship between fitness level and heart rate recovery?
d) Does there appear to be a relationship between resting heart rate and heart rate recovery?
10. How would beginning, or increasing the intensity and duration of, an exercise program affect heart rate recovery? Why?
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Teacher Materials
“We cannot change what we are not aware of, and once we are aware, we cannot help but change?”
Sheryl Sandberg
Chief Operating Officer, Facebook
Engage: How do you measure heart rate recovery?
Background: Cardiovascular disease (hear t disease and stroke) is the number one killer of adults in the United States. Nearly 800,000 people die of cardiovascular disease each year; that is one in every three deaths. Americans suffer 1.5 million heart attacks and strokes each year. The most important risk factors for cardiovascular disease include tobacco use, a sedentary lifestyle, high blood pressure, and high cholesterol. As risk factors accumulate (e.g., inactivity + high blood pressure), there is a cumula-tively greater increase in the risk for cardiovascular disease. About half of Americans (47%) have at least one of these risk factors. In addition, about 1 in 3 adults or approximately 86 million people have at least one form of cardiovascular disease. Cardiovascular disease costs the United States $320 billion a year in treatment, medication, and lost productivity. This represents one in every six health care dollars spent. It is estimated that this cost will rise to $818 billion and lost productivity to $275 billion by 2030.4
Teachers may want to begin the activity by having a brief discussion about the prevalence of heart disease in the United States. Have students read the background information then pose the question, “How many of you know someone that suffers from cardiovascular disease?” Clarify that conditions of high cholesterol or high blood pres-sure could be indicators of cardiovascular disease. Be mindful to not have students identify specific individuals with cardiovascular disease. This discussion should demonstrate to students the prolific nature of cardiovascular disease. This may be a good time to review and emphasize the cardiovascular disease risk factors.
1. What are the main components of the cardiovascular system?
Questions 1 and 2 are review questions about the basic structure and function of the cardiovascular system. Students should have enough background from prior classes to address these questions but may require some guiding questions from the instructor to assist them. Students could also use web resources to research questions 1 and 2.
The primary components of the cardiovascular system are the heart, the pump; the blood, fluid that transports oxygen and nutrients to the cells and carbon dioxide and metabolic wastes away from the cells; and the blood vessels, arteries, veins, and capillaries, the tubes through which the blood is transported.
2. What are the primary functions of the cardiovascular system?
The primary tasks of the cardiovascular system are to transport oxygen and nutrients to the cells; carry carbon dioxide and metabolic wastes away from cells; and regulate internal body temperature.
Human Heart
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3. The responsibility for the health of your cardiovascular system is largely an individual choice. Explain how that individual choice impacts the larger population health issue of cardiovascular disease in the United States.
This question is posed to show that some individual choices do not just affect the individual. When individuals choose to not take adequate measures to care for their cardiovascular systems through a healthy diet, exer-cise, adequate rest, and avoidance of tobacco products, they will more than likely suffer from some type of cardiovascular disease. As outlined in the background information, cardiovascular disease is a massive popu-lation health issue in the U.S. costing hundreds of billions of dollars in health care costs and lost productivity. These costs are passed down to all of us, the health care consumers, through increased health care and health insurance costs.
What is heart rate recovery?
Heart rate recovery refers to the speed at which your heart rate returns to the baseline pulse rate after a period of exercise. It is a useful indicator of overall cardiovascular health in that healthier individuals experience a more rapid return to the resting heart rate. When you exercise, the sympathetic nervous sys-tem (fight or flight mode) activates and the parasympathetic nervous system (rest and digest mode) with-draws. This causes an increased heart rate, increased blood pressure, and decreased blood flow to the digestive organs. When you stop exercising, the opposite process occurs: a decreased heart rate and a return of the body to homeostasis or steady state. Studies show the speed at which our heart rate declines after exercise is attributed to how quickly the nervous system shifts from sympathetic to parasympathet-ic. Delayed or impaired parasympathetic activation is an important indicator of cardiovascular health and fitness. Heart rate recovery is slowed in patients suffering from cardiovascular disease and is accelerated in well trained athletes. In essence, the less efficient your heart is, the more it has to beat (beats per mi-nute) to move blood through the body to sustain a given amount of work (e.g. jogging 4 mph). Regular cardiovascular exercise strengthens the heart muscle allowing your heart to increase the volume of blood it pumps with every beat. Heart rate recovery is one method used to measure cardiac efficiency.6
Materials:
Timer Space to do moderate exercise
4. You will be working in groups of two, three, or four. Select a volunteer from the group. The volunteer should be healthy and not suffering from any respiratory, cardiovascular, or musculoskeletal condi-tions. The volunteer should also be dressed in a manner that facilitates a brief period of moderate ex-ercise.
Be sure to monitor that the research volunteers from each group are able to tolerate a brief period of moderate exercise and that they are dressed accordingly. Be sensitive to possible medical and health issues and student privacy.
Diagram of an EKG
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5. Measuring heart rate recovery requires the volunteer to do moderate exercise until they reach their target heart rate. The target heart rate is approximately 70% of the estimated maximum heart rate (220-age). Example: if you are 15 years old, your target heart rate would be (220 – 15) x 0.70 = 144 bpm (beats per minute). Record your target heart rate in the space below and in Table 1.
Target Heart Rate = ___________
6. Your instructor will demonstrate how to measure your heart rate by finding a pulse point (either on the neck or the wrist). Count the number of heart beats you feel in 15 seconds then multiply that number by four to get your resting heart rate, beats per minute. Record your resting heart rate in the space below and in Table 1. Resting heart rate is also an indicator of cardiac efficiency. Efficient and fit hearts tend to have lower resting heart rates.
Resting Heart Rate = __________
7. To measure your heart rate recovery, you have to perform moderate exercise until your heart rate reaches the target heart rate you recorded in step 5 above. You can run in place, jog, do jumping jacks, jump rope, go up and down stairs, do burpees (squat down putting hands flat on the floor; kick the feet out to pushup position; bring the feet back to the hands; return to standing; repeat)… time and space will dictate the types of available exercise. You will generally have to exercise 3 to 5 minutes to reach the target heart rate. Check your heart rate using the steps outlined in step 6 above. As soon as you have reached your target heart, stop exercising, sit down, and measure your heart rate. Record this information in Table 1 below. Rest for two minutes then measure your heart again.
Demonstrate how to measure heart rate at both the neck and
wrist pulse points. Have students practice several times using
both pulse points before beginning data collection.
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Heart rate recovery is generally defined in terms of your biological age (e.g. the relative fitness or effi-ciency of your heart) compared to your calendar age. Below are some comparative guide lines. Check the description that best matches the data generated by the research volunteer: ("Improve Heart Health by Knowing Your Recovery Heart Rate", 2019)
8. Confer with several other groups and record the data from their research volunteer in Table 1.
Stress to students that this is not a contest to see which student has the fastest heart rate recovery. Rather, it is an opportunity for students to examine factors that may affect heart rate recovery.
9. Refer to the data in Table 1 to completely and concisely address the following questions. Be sure to defend your responses with examples from the data.
It is important that students use examples from the data to support their responses to the questions. For exam-ple, in responding to question 9c below, it is not adequate for students to simply state that there is a difference in heart rate recovery depending on fitness level or that students with higher fitness levels had better heart rate recoveries. An example of a more complete response would be that the three fitness level 1 volunteers, B. T., L. A., P. D., had heart rate recoveries of 58, 70, and 68 respectively. These were higher values than any of the oth-er volunteers.
a. Does there appear to be a relationship between age and heart rate recovery?
Since students in a given class are approximately the same calendar age, there generally will not be enough data to draw any valid conclusions. Any differences in heart rate recovery will likely be caused by other fac-tors.
b. Does there appear to be a relationship between gender and heart rate recovery?
Some studies have indicated that boys may have a slightly faster heart rate recovery than girls but this obser-vation was originally observed in populations where boys were more active. Once normalized for the amount of regular activity and fitness levels, Guilkey et. al. concluded that heart rate recovery is similar between girls and boys.3
*Biological age (also referred to physiological age) refers to how old a person seems to be from a physiological perspective. e.g. Assume you are a 15 year old and your heart rate is 142 bpm immediately after exercise. Two minutes after exercise, your heart rate is 123 bpm. Your heart rate recovery would be 142 bpm – 123 bpm = 19. According to the above chart, your biolog-ical age is older than a typical 15 year old. In other words, your heart reacts like a heart from someone older than 15.
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c. Does there appear to be a relationship between fitness level and heart rate recovery?
Students will likely see heart rate recovery differences as compared to fitness levels especially with those that are conditioned athletes. Fitness level 2 is more subjective as one person’s rigorous exercise regimen is only moderately taxing for others.
d. Does there appear to be a relationship between resting heart rate and heart rate recovery?
As stated above, resting heart rate is also an indicator of cardiovascular fitness. Volunteers with lower rest-ing heart rates will likely exhibit better heart rate recoveries.
10. How would beginning, or increasing the intensity and duration of, an exercise program affect heart rate recovery? Why?
The heart is a muscle and, like all muscle, increased exercise makes the heart muscle stronger and more effi-cient. Increased strength and efficiency allows the heart to pump more blood with each beat. Since the heart pumps more blood per beat, it does not have to beat as often or as fast resulting in improved heart rate recov-ery.
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Name
Date Class
Explore: How does exposure to particulate air pollution affect the cardiovascular system?
Background: Drs. Rudy Sinharay and J icheng Gong and their colleagues from Imper ial College in London did a pioneering air quality research study that was published in the British medical journal The Lancet in 2017. Briefly, the study involved exposing a group of volunteers to varying levels of particu-late air pollution and then measuring their respiratory and cardiovascular response for up to 26 hours af-ter the exposure. The volunteers were men and women over 60 and they were divided into three nearly equal size groups: healthy individuals; individuals with respiratory problems in the form of COPD (chronic obstructive pulmonary disorder); and individuals with cardiovascular disease in the form of is-chaemic heart disease. The volunteers were randomly assigned to two groups. One group took a two hour walk along London’s busy Oxford Street and the other group took a two hour walk through Hyde Park. The particulate pollution levels along Oxford Street were found to be significantly higher than those measured in Hyde Park. Lung and cardiovascular function were measured two hours before the walk; immediately after the walk (2 hours after starting the walk); and at 4, 6, and 26 hour intervals after start-ing the walk.
1. Use web resources to look up COPD and ischaemic heart disease. Describe the two conditions.
2. This activity focuses on the effects of exposure to particulate air pollution on the cardiovascular system. The Sinharay study mentioned above measured pulse wave velocity as an indicator of cardiovascular function. What is pulse wave velocity?
Human heart & lungs
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3. Hypothesis: make a prediction about how you think pulse wave velocity will change over time in indi-viduals exposed to the higher levels of particulate air pollution measured on Oxford Street compared to those exposed to the lower levels of particulate air pollution at Hyde Park. Be sure to explain your pre-diction.
Use the coordinate systems on the next page to graph the data from Table 1 above: time is the independ-ent variable on the x-axis and percentage change of pulse wave velocity, pwv, is the dependent variable on the y-axis. Designate one graph for the healthy group, one for the COPD group, and one for the is-chaemic heart disease group. Draw a dashed horizontal line at 0% pwv change on each graph to represent the baseline—the initial resting pwv measure. Since these are trend line graphs, use a straight edge to connect the plotted points. Be sure your graphs exhibit all of the properties of properly constructed graphs.
Data
Table 1: Average percentage change in pulse wave velocity on Oxford Street vs. Hyde Park*
*Data was adapted from the Sinharay study (Sinharay et al., 2017).
Research
Group
Location 2 hrs. Prior
End of walk, 2 hrs. after start
4 hrs. after start
6 hrs. after start
26 hrs. after start
Healthy Oxford St. 0 -1 +2 +3 +7
Hyde Park
0 -5 -3 -2 -4
COPD Oxford St. 0 +2 +3 +4 +4
Hyde Park
0 -6 -5 -2 -4
Ischaemic Heart Disease
Oxford St. 0 +1 +5 +4 +3
Hyde Park
0 -7 -5 -2 -5
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Explain
4. Describe the overall trend in pulse wave velocity among the three study groups on Oxford Street and in Hyde Park.
5. According to the data, is it better to undertake moderate exercise such as walking when particulate air pollution levels are elevated or is it better to limit exertion to cleaner air environments? Defend your response using examples from the data.
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 20
6. The PM2.5 (air particulates with a diameter of 2.5 µm or smaller – small enough to be respirable) levels Sinharay measured on Oxford Street varied from 5 – 39 µg/m3 with a median or middle val-ue of 17 µg/m3. In contrast, PM2.5 concentrations measured during the Rice Ridge Fire near Seeley Lake, Montana in 2017 varied from 19.1 – 636.8 µg/m3 and the median value was 187.5 µg/m3. How do you think exercising in the form of a sport practice during a forest fire smoke event would affect the cardiovascular system?
Conclusion: revisit your hypothesis and write a conclusion for this activity. Begin by re-stating your hypothesis, discuss its validity, and use examples from the data to support your conclusion.
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 21
Teacher Materials
Explore: How does exposure to particulate air pollution affect the cardiovascular system?
Background: Drs. Rudy Sinharay and J icheng Gong and their colleagues from Imper ial College in London did a pioneering air quality research study that was published in the British medical journal The Lancet in 2017.10 Briefly, the study involved exposing a group of volunteers to varying levels of particu-late air pollution and then measuring their respiratory and cardiovascular response for up to 26 hours af-ter the exposure. The volunteers were men and women over 60 and they were divided into three nearly equal sized groups: healthy individuals; individuals with respiratory problems in the form of COPD (chronic obstructive pulmonary disorder); and individuals with cardiovascular disease in the form of is-chaemic heart disease. The volunteers were randomly assigned to two groups. One group took a two hour walk along London’s busy Oxford Street and the other group took a two hour walk through Hyde Park. The particulate pollution levels along Oxford Street were found to be significantly higher than those measured in Hyde Park. Lung and cardiovascular function were measured two hours before the walk;
The respiratory effects of exposure to air particulates are well documented and will not be explored in this activi-ty. Because of the new REACH Program emphasis of particulate air quality and cardiovascular health, cardiovas-cular effects will be the focus of this activity.
1. Use web resources to look up COPD and ischaemic heart disease. Describe the two conditions.
COPD is a term used to describe a group of progressive lung diseases including em-physema, chronic bronchitis, and refractory or non-reversible asthma. COPD is char-acterized by breathlessness and is currently incurable.12
Ischaemic heart disease is a condition caused by narrowed heart arteries. When these arteries narrow, less blood, oxygen, and nutrients reach the heart muscle. Symptoms vary but can include chest pain and shortness of breath. However, many people do not exhibit any symptoms. Ischaemic heart disease is also called coronary artery disease or coronary heart disease. Ischaemic heart disease is the leading cause of death in the United States.7
2. This activity focuses on the effects of exposure to particulate air pollution on the cardiovascular sys-tem. The Sinharay study mentioned above measured pulse wave velocity as an indicator of cardiovas-cular function. What is pulse wave velocity?
Pulse wave velocity is a measure of the rate at which pressure waves move down a blood vessel. It is a measure of arterial stiffness and is a highly reliable predictor for cardiovascular morbidity and mortality in a variety of adult populations. Pulse wave velocity is measured by using two pressure catheters placed a known distance apart. When blood vessels become stiffer, pulse wave velocity increases.9 The key point, increased pulse wave velocity is an indicator of increased arterial stiffness and is not healthy.
Human heart & lungs
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 22
3. Hypothesis: make a prediction about how you think pulse wave velocity will change over time in indi-viduals exposed to the higher levels of particulate pollution on Oxford Street compared to those ex-posed to the lower levels of particulate pollution at Hyde Park. Be sure to explain your prediction.
Responses will vary however, it is important that students provide reasonable explanations for their predic-tions. Example: if research volunteers perform moderate exercise in both high particulate air pollution and low particulate air pollution areas, then those volunteers in the higher particulate air pollution areas will demon-strate lower cardiovascular efficiency as measured by pulse wave velocity. Exposure to higher particulate air pollution levels causes stress and inflammation in the respiratory system interfering with its ability to deliver oxygen. Since all body systems, including the cardiovascular system, are dependent on the respiratory system to deliver oxygen to the tissues, the cardiovascular system should exhibit stress in response to respiratory system stress as indicated by higher pulse wave velocities. Re-enforce to students that higher pulse wave velocities, a positive percentage change, occur because of increased arterial stiffness. This is a negative effect of increased particulate air pollution exposure.
Use the coordinate systems on the next page to graph the data from Table 1 above: time is the independ-ent variable on the x-axis and percentage change of pulse wave velocity, pwv, is the dependent variable on the y-axis. Designate one graph for the healthy group, one for the COPD group, and one for the is-chaemic heart disease group. Draw a dashed horizontal line at 0% pwv change on each graph to represent the baseline—the initial resting pwv measure. Since these are trend line graphs, use a straight edge to connect the plotted points. Be sure your graphs exhibit all of the properties of properly constructed graphs.
Data
Table 1: Average percentage change in pulse wave velocity on Oxford Street vs. Hyde Park*
*Data was adapted from the Sinharay study (Sinharay et al., 2017).
Research
Group
Location 2 hrs. Prior
End of walk, 2 hrs. after start
4 hrs. after start
6 hrs. after start
26 hrs. after start
Healthy Oxford St. 0 -1 +2 +3 +7
Hyde Park
0 -5 -3 -2 -4
COPD Oxford St. 0 +2 +3 +4 +4
Hyde Park
0 -6 -5 -2 -4
Ischaemic Heart Disease
Oxford St. 0 +1 +5 +4 +3
Hyde Park
0 -7 -5 -2 -5
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 23
Students will use scatter plots to graph the data from Table 1. They will be finding trends, not lines of best fit, so they should use a straight edge to draw lines connecting the graphed points. Students may require some assistance setting up the coordinate systems because of the use of negative values and the fact that the first data point is measured two hours before the walk is initiated (see examples below). Emphasize to students they are not gra-phing actual pulse wave velocities but rather, average percentage change in pulse wave velocity. Looking at the Healthy group data collected at the end of the walk, the group that walked through Hyde Park showed a pulse wave value of -5. That corresponds to an average 5% drop in pulse wave velocity for the Healthy group immedi-ately after concluding the two hour walk through Hyde Park. A drop in pulse wave velocity indicates increased arterial flexibility, a healthy cardiovascular response to the exercise.
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 24
Remember, a positive percentage
change in PWV indicates pulse waves
are moving faster, the blood vessels are
becoming more rigid—this is a de-
crease in cardiovascular function!
Explain
4. Describe the overall trend in pulse wave velocity among the three study groups on Oxford Street and in Hyde Park.
The three research groups generated similar data sets. Examination of the three graphs shows that the Ox-ford Street groups showed an average percent increase in pulse wave velocity over time with the healthy group exhibiting the largest increase of 7% above the baseline. Conversely, the Hyde Park groups uniformly displayed a negative percent change in pulse wave velocity. Each group showed at least a 5% drop in pulse wave velocity at the completion of the walk (two hours after beginning the walk) and each group exhibited a 4-5% decrease in pulse wave velocity 26 hours after beginning the walk.
5. According to the data, is it better to undertake moderate exercise such as walking when air particu-late levels are elevated or is it better to limit exertion levels to cleaner air environments? Defend your response using specific examples from the data.
The data suggests that individuals should avoid exertion during periods of high air particulate levels. The three graphs show that volunteers that walked for two hours along Oxford Street experienced an increase in pulse wave velocity. Additionally, the three groups had pulse wave velocities higher than their baselines at 26 hours after beginning the walk with healthy individuals experiencing the largest pulse wave velocity increase at 7%. “This finding suggests that exercise benefit was not only negated but even reversed 26 hours after beginning the walk. Multifactorial ben-efits of low-to-moderate intensity physical activity, such as walking, for the primary and secondary prevention of cardiovascular disease were offset by the presence of air pollution.”11
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 25
6. The PM2.5 (air particulates with a diameter of 2.5 µm or smaller – small enough to be respirable) lev-els Sinharay measured on Oxford Street varied from 5 – 39 µg/m3 with a median or middle value of 17 µg/m3. In contrast, PM2.5 concentrations measured during the Rice Ridge Fire near Seeley Lake, Montana in 2017 varied from 19.1 – 636.8 µg/m3 and the median value was 187.5 µg/m3. How do you think exercising in the form of a sport practice during a forest fire smoke event would affect the cardiovascular system?
Placing more stress on the cardiovascular system through exposure to significantly higher particulate air pol-lution concentrations should produce pulse wave velocity responses at least equal to those observed in the Sin-haray study. In all probability, the cardiovascular responses would be more drastic and longer lasting than those measured in the study because of the additional cardiovascular demands of more vigorous exercise and exposure to higher particulate air pollution levels. One reason for this outcome is that performing more physi-cal work requires a proportional increase in the breathing rate and depth, called “ventilatory rate”. Thus, an increase in ventilation means more particulate is inhaled and presumably will have a more significant impact on the cardiovascular system.
In the paper, Exposure of Firefighters to Particulates and Polycyclic Aromatic Hydrocarbons, Baxter found that fire fighters did exhibit higher tendencies of cardiovascular disease.2 It is suspected that the physical de-mands experienced while performing the duties of firefighting resulted in a higher breathing rate, and in the end, a larger impact of particulate inhalation on the cardiovascular system.
Conclusion: revisit your hypothesis and write a conclusion for this activity. Begin by re-stating your hypothesis, discuss its validity, and use examples from the data to support your conclusion.
Answers will vary depending on the nature of the hypothesis. Using the example hypothesis from #3 above, a pos-sible conclusion would be: the hypothesis if research volunteers perform moderate exercise in both high air par-ticulate and low air particulate areas, then those volunteers in the higher air quality particulate areas will demonstrate lower cardiovascular efficiency as measured by pulse wave velocity appears to be supported by the data. The graphs of Pulse Wave Velocity vs. Time for the three research groups show that volunteers that walked along Oxford Street, area of higher particulate air pollution levels, uniformly exhibited increases in pulse wave velocity. Each group also had higher pulse wave velocities at 26 hours after beginning the walk than they did pri-or to the walk. Conversely, the groups that walked in Hyde Park, area of lower particulate air pollution levels, experienced lower pulse wave velocities with each group having a lower pulse wave velocity at 26 hours after the beginning of the walk than they did prior to the walk.
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 26
Name
Date Class
Evaluate
Answer the following questions completely and concisely.
1. How is heart rate recovery measured? Why is heart rate recovery an indicator of cardiovascular health and fitness?
2. How does individual cardiovascular health affect overall population and community health?
3. Recall the Sinharay et. al. study featured in the explore activity: How does exposure to particulate air pollution affect the cardiovascular system? This study used pulse wave velocity as an indicator of the effect of exposure to air particulates on the cardiovascular system. The study also used another factor, augmentation index, to measure possible cardiovascular system response. As with pulse wave veloci-ty, higher augmentation index values indicate decreased cardiovascular fitness. The following aug-mentation index data was collected for the healthy volunteer group:
Does this data corroborate, refute, or provide no basis for a conclusion when compared to the pulse wave velocity data featured in the explore activity? Defend your answer.
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 27
Teacher Materials
Evaluate
Answer the following questions completely and concisely.
1. How is heart rate recovery measured? Why is heart rate recovery an indicator of cardiovascular health and fitness?
Heart rate recovery is measured by determining the target heart rate; performing moderate exercise until the target heart rate is reached; measuring the heart or pulse rate at the conclusion of the exercise; then measur-ing the heart rate again two minutes after concluding the exercise. Heart rate recovery is calculated by sub-tracting the heart rate at two minutes after the exercise from the heart rate at the conclusion of exercise. The bigger the difference, the more rapidly the heart slows, the more healthy/fit the heart is.
Heart rate recovery is a measure of the efficiency of heart function. The heart is a muscle, and as with all mus-cles, the more it is exercised, the stronger and more efficient it becomes. As the heart becomes stronger, it can pump a greater volume of blood with each beat. Therefore, a fit heart will exhibit a slower heart rate and will recover more quickly after exertion.
2. How does individual cardiovascular health affect overall population and community health?
When individuals choose to not get regular exercise, consume unhealthy foods, not get adequate rest, or use tobacco products they are placing stress on their hearts that may lead to cardiovascular disease – heart attack and stroke. Cardiovascular disease is the leading cause of mortality of adults in the United States – one in every three deaths. The annual cost of cardiovascular disease is hundreds of billions of dollars in health care costs and lost productivity. The individual lifestyle choices of millions of Americans are resulting in a popula-tion health crisis.
3. Recall the Sinharay study featured in the explore activity: How does exposure to particulate air pollu-tion affect the cardiovascular system? This study used pulse wave velocity as an indicator of the ef-fect of exposure to air particulates on the cardiovascular system. The study also used another factor, augmentation index, to measure possible cardiovascular system response. As with pulse wave veloci-ty, higher augmentation index values indicate decreased cardiovascular fitness. The following aug-mentation index data was collected for the healthy volunteer group:
The REACH Program is funded by a National Institute of Health Science Education Partnership Award. Page 28
Does this data corroborate, refute, or provide no basis for a conclusion when compared to the pulse wave velocity data featured in the explore activity? Defend your answer.
The augmentation index data for healthy individuals from Table 1 corroborates the results from the pulse wave velocity data. Both data sets demonstrate an overall increase in cardiovascular fitness, low pulse wave veloci-ties and augmentation indexes, over the duration of the study for those individuals that walked in the lower air particulate environment in Hyde Park. As with pulse wave velocity, the augmentation index 26 hours after the start of the walk was considered to be at a healthier level than when the individuals began the walk. Converse-ly, the volunteers that walked in the higher air particulate environment on Oxford Street exhibited increases in pulse wave velocity and augmentation index indicating decreased cardiovascular fitness. Both values for this group were higher 26 hours after the start of the walk than prior to the walk. This shows that the benefits of the exercise were not only negated, they were reversed.
(Augmentation index is actually another method for measuring the degree of arterial stiffness. Briefly, it is a measure of the pressure wave generated along the aorta during left ventricle contraction compared to the pres-sure wave that is eventually reflected back to the heart. It is measured with a specialized blood pressure cuff that contains a vibration sensor. As with pulse wave velocity, the faster the waves, the stiffer the arteries so high augmentation index values are an indication of a less fit cardiovascular system. Think of a blood vessel as a garden hose. A supple or pliable garden hose is preferable to a brittle stiff hose. A supple garden hose would have a lower pulse wave velocity and a lower augmentation index. Because pulse wave velocities and augmen-tation index are both measures of arterial stiffness, it is reasonable that the augmentation index data mirrors the pulse wave velocity data.)
An example graph of augmentation index where the reflected pulse
wave has traveled faster (indicating less flexible arteries) back towards
the heart in the older individual compared to the younger individual.
