Physical activity and cardiovascular disease - Term Paper Example

?Physical Activity and Cardiovascular Disease Introduction – The magnitude of the problem Cardiovascular disease is a major health problem in the United States of America. It has remained the leading cause of death for almost 50 years. According to the data of the American Heart Association, deaths due to cardiovascular disease, specifically coronary heart disease have steadily risen in the twentieth century. (Lloyd-Jones, 2009) In 1900, coronary heart disease was believed to have caused 27,000 deaths. These numbers increased progressively to peak at a rate of 770,000 deaths in 1985. Since then, due to sustained campaigns by various association in increasing awareness of various health lifestyle habits, deaths due to coronary heart disease has reduced to 446,000 in 2005. However, overall, cardiovascular diseases still caused 850,000 deaths in adult population in 2005. This represents a large burden on the healthcare system, consuming scarce resources and manpower. A majority of these deaths are considered to be preventable through lifestyle modifications. Risk factors for cardiovascular disease Several risk factors have been identified for cardiovascular disease. These include hypertension, type 2 diabetes mellitus, elevated LDL and VLDL cholesterol, elevated triglycerides, low HDL cholesterol, elevated homocysteine levels, obesity, stress, smoking and sedentary lifestyle. By bringing about certain simple lifestyle changes, these risk factors can be greatly reduced or eliminated, thus, greatly decreasing the morbidity and mortality from cardiovascular diseases. The commonest three lifestyle changes that can be practiced by everyone are cessation of smoking, dietary modifications and physical activity. The benefits of smoking are self-evident. Johnston has clearly shown the benefits of simple dietary modifications. (Johnston, 2009). Two specific diets, viz., the Mediterranean diet and vegetarian diets were discussed. The Mediterranean diet is high in fruits, vegetables, cereals, beans, nuts and seeds and olive oil. Red meat is rarely eaten and fish and dairy products are eaten sparingly. The vegetarian diet is rich in vegetables, fruits, nuts and dairy products. These food substances are high in anti-oxidants and polyphenols (protective substances against coronary heart disease) and low in arachidonic acid (increases risk for coronary heart disease). The types of foods included in these two diets are collectively called functional foods. Physical activity and cardiovascular disease There have been several studies that have established the connection between lack of physical activity and cardiovascular disease. Framingham is a town outside Boston which has become renowned across the world because of a unique experiment which was started in 1948 – to study the population for various aspects of cardiovascular disease and follow the subjects over a prolonged period of time and even unto the second and third generations. As a part of this project, Kannen and Sorlie (1979) studied 1909 men and 2311 women aged 35-64 years and followed them up for 14 years. They tried to find out the relationship between physical activity index based on hours per day spent at activity-specific intensity and cardiovascular disease incidence and death. They found that there was an inverse association between physical activity index and mortality as well as incidence of cardiovascular disease. The mortality and incidence also varied inversely according to the duration and intensity of physical exercise. (Kannen and Sorlie, 1979). The INTERHEART study in 2004 established physical inactivity as one of the 9 major contributors to deaths due to cardiac disease. It was an international, multi-center case-control study to identify the risk factors for myocardial infarction and the magnitude of their impact. The study identified 9 easily measured risk factors that account for over 90% of the risk for acute myocardial infarction. These risk factors are smoking, blood lipid levels, hypertension, diabetes, obesity, diet, physical activity, alcohol consumption and psychosocial factors. These factor remain constant worldwide despite geographical, racial and ethnic variations and are consistent in men as well as women. Physical inactivity was found to have contributed to 12% of myocardial infarctions, after hypertension (18%) but ahead of diabetes mellitus (10%). There is a consistent dose response association between the levels of physical activity and decreases in morbidity and mortality due to coronary heart disease. Lack of exercise conferred a high risk for myocardial infarction (an Odd’s ratio of 0.86). (INTERHEART, 2004). The US Centers for Disease Control (CDC) and the American College of Sports Medicine (ACSM) in 2005 recommended at least 30 minutes a day of moderate intensity physical activity on most days of the week. (Pate, 1995) Moderate intensity physical activity performed regularly did reduce the risk for coronary heart disease, among other chronic diseases. A later clarification in 2007 mentioned a frequency of 5 days a week and suggested a combination of moderate and vigorous physical activity. The other significant studies on this subject are summarized in Table 1. Table 1. Population-based studies of association of physical activity as related to cardiovascular disease (CVD): CVD – Cardiovascular Disease. CHD – Coronary Heart Disease. The benefits of exercise on the cardiovascular system are summarized in table 2 Table 2. Benefits of exercise on cardiovascular system Variable Benefit Cardiovascular pathophysiology Maximal cardiac output Increased Peripheral oxygen extraction Increased Myocardial oxygen demands Decreased Fibrinolysis Increased Blood coaguability Decreased Endothelial function Increased Myocardial blood flow Increased Sympathetic hyperactivity Decreased Cardiovascular risk factors Resting blood pressure Decreased High density lipoprotein cholesterol Increased Triglycerides Decreased Body weight control Increased Insulin resistance Decreased Physical function Fitness/strength Increased Exercise capacity Increased Performance of activities of daily living Increased Return to work Increased Psychosocial wellbeing Depression Decreased Anxiety Decreased Quality of life Increased Wise, F.M. (2010) Prevalence of physical activity in US The Center for Diseases Control describes the Behavioral Risk Factor Surveillance System (BRFSS) used to determine the prevalence of physical activity in the population. (CDC, 2002). The survey asked participants regarding their participation in a level of physical activity as described previously by Pate etal. (Pate etal, 1995). This report published data and compared the prevalence of physical activity in US adults, both nationally as well as state-wise. This is a population-based, random-digit-dialled telephone survey of the civilian, non-institutionalized US population 18 years of age or older in the 50 states, the District of Columbia, Guam, Puerto Rico and the U.S. Virgin Islands. A total of 205,140 individuals responded to the survey in 2001. The physical activity was classified under two levels – moderate-intense and vigorous-intense. The survey also asked the respondents to report frequency and duration of the two most common leisure-time physical activities or exercises that they indulged in during the preceding month. Examples of moderate-intense physical activity included vacuuming, gardening, brisk walking or bicycling. Vigorous-intense physical activity meant participating in running, aerobics, swimming or heavy yard work. Respondents were classified as active at the recommended level if they participated in at least 30 minutes per day of moderate-intense activity for at least 5 days a week or at least 20 minutes of vigorous-intense activity per day for at least 3 days a week. It was found that only 45.4% of US adults achieved the target of specific level of physical activity. State-wise, Wyoming had the highest prevalence of adequate physical activity (55.8%) while Kentucky had the lowest (28.9%). It concluded that the majority of U.S. adult population was not physically active on a regular basis. What was even more disturbing was the fact that overall 26% of the population reported no leisure-time physical activity at all. While considering the reasons for low prevalence of healthy physical activity in US, Heath (2009) considers the changes in social and demographic patterns in the last 40 years as causal factors. There has been a 10 fold rise in the use of automobiles, a reduction in the time spent by children in activity during physical education classes, a decrease in the amount of physical activity required to perform one’s work as well as the intensity of physical effort during non-work pursuits. (Heath, 2009) Physical activity in presence of cardiovascular disease Exercise programs and cardiac rehabilitation can reduce cardiac mortality by 26% (Taylor, R.S., 2000). The rate of myocardial infaction recurrence also decreases after cardiac rehabilitation as does the rate of hospital re-admission in cardiovascular disease patients. Patients with cardiovascular disease should aim, over time of including 30 minutes of moderat-intensive physical activity, e.g. brisk walking, most days of the week. All such physical activities should be in close consultation with their family physician or health care provider. The way forward After examining all the evidence on this topic, the Council on Clinical Cardiology came out with several recommendations in 2003: (Thompson, P.D. etal, 2003) 1. Physical activity is important for preventing coronary artery disease; managing some of the risk factors for coronary artery disease like raised blood lipid levels, hypertension, diabetes, obesity; treating patients with coronary artery disease and heart failure. 2. Healthcare professionals should themselves engage in an active and healthy lifestyle so that they may become familiar with the issues involves. 3. Healthcare professionals should interact with the education system to promote teaching habits needed for physically active life. 4. They should also engage with the community and contribute to setting up programs and facilities that encourage physical activities. 5. They should be aware of exercise as a treatment option and the value of lifelong physical activity in their patients. 6. Healthcare professionals should routinely prescribe exercises to their patients in accordance with the guidelines provided by the Center for Diseases Control and American Heart Assocation. 7. Before patients embark on vigorous exercises, symptomatic patients and those at high risk should undergo stress testing. Further research is also required to devise behavioral strategies to encourage people to maintain an active and healthy lifestyle. An example of such a program is the First Step Program developed by Dr. Catrine Tudor-Locke. (Tudor-Locke, C. 2009) It uses a pedometer to provide the participant a stimulus for walking. The pedometer helps the participant to set individual goals, provides an incentive to achieve this goal and perform self-monitoring. The participants note the distances walked daily on calendars and their efforts are reviewed at weekly group support meets which also helps in motivating them for giving it up. Several reasons are advanced for the success of the First Step Program. Wearing a pedometer is not intrusive and so persons participating in the program do not have to do anything special. As they wear the pedometer throughout the day, the device measures their activity not only during leisure time, e.g, when they go out for a brisk walk, but also during their routine daily chores. It provides them with a sense of well-being and accomplishment. Several trials that adopted this program did find that participants walked an increasing number of steps and were motivated to maintain this level. However, for persons embarking on a program of physical activity for the first time, a note of caution is to be struck. If there is any chest pain or angina, one should stop immediately and call for medical assistance. A little shortness of breath is expected on exercising. However, one should not be gasping for breath and should be able to talk. Before embarking on an exercise program, one should consult one’s physician and find out what is the maximum permissible heart rate. While exercising, if one can take one’s own pulse (many gymnasium instruments have facility to measure your heart rate), and if the heart rate goes beyond the maximum permissible limit, stop immediately. After a bout of exercise, one should get one’s breath back in 3-5 minutes. If this is not happening, reduce the amount of exercise. It is normal to be hot and sweaty while exercising but not cold and clammy. If one notices these symptoms and is perspiring heavily, stop immediately. Another sign of excessive exercising is a feeling of tiredness and weakness the next morning or in the evening. One should not exercise if unwell due to any other reason. In conclusion, there is ample evidence to show that physical activity is highly beneficial to health in general and to the cardiovascular system in particular. The level of physical activity amongst adult US population is poor and this correlates with the high prevalence of cardiovascular diseases. By adopting simple lifestyle changes or community based programs, the habit of regular moderate to intense physical activity can be inculcated in people to encourage a healthy lifestyle. References Bijnen, F. V. H., Caspersen, C. J., Feskens, E. J. M., Saris, W. H. M., Mosterd, W. L. and Kromhout, D. (1998). 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Thompson, P.D., etal, (2003) (Exercise and physical activity in the prevention and treatment of atherosclerotic cardiovascular disease: a statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity). Arteriosclerosis, Thrombosis and Vascular Biology, 23, c42-c49. Tudor-Locke, C. (2009). Promoting lifestyle physical activity: experiences with the first step program. American Journal of Lifestyle Medicine, 3(1), 50s-54s. Wise, F.M. (2010). Coronary heart disease: the benefits of exercise. Australian Family Physician, 39(3), 129-133. Yusuf S, Hawken S, Ounpuu S, on behalf of the INTERHEART Study Investigators. (2004). Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet, 364, 937-952. Read More