Physical activity and cornonary heart disease

Fifty years of research confirms inverse relationship, say G David Batty and I-Min Lee

Fifty years ago the first empirical investigation of what was subsequently termed "the exercise hypothesis"-physical activity reduces the occurrence of coronary heart disease-was undertaken by Morris et al.^w1 Using data from two cohorts of British workers, they reported lower rates of coronary heart disease in bus conductors than in less occupationally active bus drivers, and in postmen relative to deskbound telephonists and other office based employees. Although this research was pioneering, it was not without its shortcomings. Early statistical methods were limited in their capacity to explore the issue of confounding-for example, it was possible that higher levels of overweight, high blood pressure, stress, or pre-existing ischaemia in the less active groups, rather than their sedentary behaviour, placed them at increased risk of coronary heart disease. Further, the study focused exclusively on work activity. Morris et al, and subsequently Paffenbarger et al, went on to address these issues, showing physical activity in leisure time to be cardioprotective, an effect that held after controlling for a range of covariates.^{w2 w3}

The work of these researchers prompted a series of other investigations, including the study of the association between cardiorespiratory fitness-a physiological outcome of physical activity and therefore an objective proxy for it-and cardiovascular disease, which showed that higher levels, which were none the less eminently attainable by non-athletes, conferred protection against coronary heart disease.^w4 These studies, and those of physical activity, represent a range of methodological rigour and have, with few exceptions, shown an inverse association between activity and coronary heart disease, which is testimony to the robustness of the relation. Until recently this research has focused on men. In the past two decades, however, the same degree of consistency has been observed in women-a dose-response effect is again evident, with the highest rates of coronary heart disease seen in people who are inactive or have low cardiorespiratory fitness. This level of risk may be of slightly lower magnitude than that reported in men.

LES WILSON/REX FEATURES

Jensen; you need more than a treadmill to beat Schumacher

We still do not fully understand the pathways underlying the protective effect of physical exertion against coronary heart disease. In addition to well established improvements in blood pressure, lipid profile, insulin sensitivity, and body weight, activity may improve endothelial function and coronary blood flow and may be associated with beneficial changes in haemostatic and inflammatory variables.^{w5 w6} These warrant further examination. Given the public’s reluctance to be physically active, future research also needs to identify the minimum dose (the total volume of activity, as well as the intensity, duration, and frequency), type (aerobic, strength training), and mode (walking, swimming) of activity associated with reduced coronary heart disease risk that will be most palatable to the sedentary populations. For the prevention of a range of chronic diseases, including coronary heart disease, the current recommendation is 30 minutes or more of moderately intense aerobic activity such as brisk walking or cycling on five or more occasions per week.^w7 Worryingly, however, the prevalence of activity in most Western societies does not match this: in England, for example, only about one quarter of men and women currently achieve this level,^w8 and these figures are lower still in elderly people.

For the sedentary majority, commonly cited barriers to participation include inconvenience (for example, lack of easily accessible facilities) and danger (in the United States injuries and fatalities among pedestrians and cyclists far exceed those for car occupants). Therefore, efforts to promote activity that focus on personal behaviour change-often delivered via face to face contact in a small group-may not be sufficiently effective. An alternative approach is one that also recognises the importance of physical and social environments as crucial determinants of physical activity both of a utilitarian nature and for leisure. Utilitarian activity levels seem to be higher in residentially dense neighbourhoods in mixed use (business and residential) that offer a greater concentration of street connections than neighbourhoods that are more sprawling in design where, presumably by necessity, travel by motorised transportation predominates.^w9 Perhaps because of these differing degrees of physical activity, people residing in more compact neighbourhoods are also less likely to report obesity and hypertension.^w10 Moreover, in Japan the life expectancy of people with more easy access to facilities conducive to physical activity in leisure time,such as parks and tree lined streets, exceeds that of people without such resources, even after the obvious and important socioeconomic differences between such areas are taken into account.^w11 Although the governments of many countries, including the United Kingdom, have the opportunities to implement such changes in urban form in order to make environments more conducive to physical activity, what they may lack is the political resolve. This may be short sighted. Given the high prevalence of sedentary behaviour and its association with a range of chronic diseases-which include not only coronary heart disease, but also stroke, type 2 diabetes, certain cancers, and osteoporotic fractures^w12-modification of physical activity may, as Morris indicated four decades after the publication of his seminal work, represent today’s best buy in public health.^w13

G David Batty, Department of Social Medicine, Institute of Public Health, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
Email: david.batty@pubhealth.ku.dk

I-Min Lee, associate professor of medicine senior research fellow in epidemiology Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, 900 Commonwealth Avenue East, Boston, MA 02215, USA


studentBMJ 2004;12:265-308 July ISSN 0966-6494

1. Morris JN, Heady JA, Raffle PAB, Roberts CG, Parks JW. Coronary heart-disease and physical activity of work. Lancet 1953;ii:1053-7, 1111-20.
2. Morris JN, Chave SPW, Adam C, Sirey C, Epstein L, Sheehan DJ. Vigorous exercise in leisure-time and the incidence of coronary heart-disease. Lancet 1973;i:333-9.
3. Paffenbarger RS, Wing AL, Hyde RT. Physical activity as an index of heart attack risk in college alumni. Am J Epidemiol 1978;108:161-75.
4. Wilhelmsen L, Bjure J, Ekstrom-Jodal B, Aurell M, Grimby G, Svardsudd K, et al. Nine years’ follow-up of a maximal exercise test in a random population sample of middle-aged men. Cardiology 1981;68:1-8.
5. Hambrecht R, Wolf A, Gielen S, Linke A, Hofer J, Erbs S, et al. Effect of exercise on coronary endothelial function in patients with coronary artery disease. N Engl J Med 2000;342:454-60.
6. Wannamethee SG, Lowe GD, Whincup PH, Rumley A, Walker M, Lennon L. Physical activity and hemostatic and inflammatory variables in elderly men. Circulation 2002;105:1785-90.
7. Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, Bouchard C. Physical activity and public health. JAMA 1995;273:402-7.
8. Erens B, Primatesta P. Health survey for England. Cardiovascular disease. Volume 1: findings. London: Stationery Office, 1999.
9. Saelens BE, Sallis JF, Frank LD. Environmental correlates of walking and cycling: findings from the transportation, urban design, and planning literatures. Ann Behav Med 2003;25:80-91.
10. Ewing R, Schmid T, Killingsworth R, Zlot A, Raudenbush S. Relationship between urban sprawl and physical activity, obesity, and morbidity. Am J Health Promot 2003;18:47-57.
11. Takano T, Nakamura K, Watanabe M. Urban residential environments and senior citizens’ longevity in megacity areas: the importance of walkable green spaces. J Epidemiol Community Health 2002;56:913-8.
12. US Department of Health and Human Services. Physical activity and health: a report of the surgeon general. Atlanta: US Department of Health and Human Services, 1996.
13. Morris JN. Exercise in the prevention of coronary heart disease: today’s best buy in public health. Med Sci Sports Exercise 1994;26:807-14.

       

           

	EDITORIALS Physical activity and cornonary heart disease       G David Batty and I-Min Lee (July 2004)
	Muhammad Ahsan Saleem January 13th, 2006       Clinical observer,Addenbrooke's Hospital, Cambridge. dr_ahsan@yahoo.com
	Regarding the factors increasing the risk of CAD, the better idea would be to compare the risk factors in different societies, races and countries. The important cause of CAD is developed countries is the pre-dominant sedentary life style where as compared to in under-developed countries it is due to mantle and psychological tensions and work load. Though government has a role to play but it is also the duty of people specially the health related staff to make people aware about the incidence and causes of CAD and also to guide them to minimise the risk factors. People living in rural areas have less chances of having CAD because: People living in rural areas have to do more physical exertion during their working hours as compared to people working in cities. Secondly, Working style in cities has influenced the eating habits of people, which also add to the high risk of CAD in urban areas as compared to people in rural areas. So, I think that we should help the government to practice a healthy working environment in cities with integrating light physical activities during work and minimising the working stress as well.

	EDITORIALS Physical activity and coronary heart disease       G David Batty and I-Min Lee (July 2004)
	Laxmi Vilas Ghimire (July 23, 2004)       fourth year, MBBS TUTH, Kathmnadu,Nepalvilas_laxmi@iom.edu.np
	Although the coronary heart disesae was considered the disease of the well-to-do societies its prevalence in the developing countries canot be underestimated as it has been upsurging in recent years. In 2002 we all celebrated world health day with the slogan 'move for health'. With this celebration the importance of physical activity even in the form of walking, cycling and swimming; which can be easily done in the set up of developing countries was emphasized which indeed helped many to understand its importance. But in the urban areas of these countries there are hardly any places where one can go roaming on foot or cycling to involve oneself in daily physical activities to refresh oneself. As the political committment towards any health matters is very less we can hardly expect the government to provide public areas to help people help involve in physical activities. When the people understanding the importance of physical activity is low, those who know it are also discouraged due to lack of proper facilities and increased paedistrain accidents( hidrance to walking to work etc,). So, i think every government should take enough care to facilitate people for physical activities to decrease the burden of coronary heart disease which would cost many fold higher than in preventing it through easier means.

	EDITORIALS Physical activity and cornonary heart disease       G David Batty and I-Min Lee (July 2004)
	Mona Hedayat (December 16th, 2005)       medicine-second year , Tehran university-Iran mona_hedayat@yahoo.com
	Coronary Artery Disease(CAD) is the commonest cause of uncommunicable chronic diseases all over the world.Despite the communicable diseases there are very little information about the agents which cause the disease.CAD is a multifactorial disease and is a medical,personal and social complication which affect all part of the society. It has been shown that the distribution of the disease and the high prevalence of the risk factors are coincident. Among the risk factors smoking,dyslipidemia, hypertension and sedentary life style seem to be the most serious ones.Most of the people do not have physical activities and if they do, it is not enough to decrease the incidence of coronary artery disease.An appropriate type of exercise should increase the heart beat to 70% of maximal heart rate. CAD is a fatal disease and should be taken seriously.So in my point of view the governments should provide their citizens with accessible and safe facilities inorder to help them change their lifestyle and educating is necessary but it is not enough.Even a little change in the life habits is very difficult so these type of planning should be considered in a long period of time and the earlier they are started the better are the results. though it.