Reduction of coronary atherosclerosis by moderate conditioning exercise in monkeys on an atherogenic diet

Exercise in the prevention of coronary heart disease

Epidemiological studies have left no doubt as to the existence of a strong inverse relationship between physical exercise and coronary heart disease (CHD) risk. British studies of transport workers and civil servants, together with American studies of stevedores and college alumni, have provided persuasive evidence that contemporary vigorous activity is accompanied by lower risk of both fatal and nonfatal CHD. The relationship is largely independent of influential characteristics of high risk such as cigarette smoking, hypertension, obesity, and family history of hypertensive--atherosclerotic disease. Recent studies of occupational or leisure physical exercise among residents of Framingham, Massachusetts, the state of Iowa, four residential areas of Holland, urban--rural sections of Puerto Rico, Seattle--King County, Washington, city employees in Los Angeles, and various regions of Finland and Norway support the likelihood that the inverse relationship of exercise and CHD is causal, signifying a protective effect of exercise rather than an incidental contrast due to a selective influence of precursive CHD symptoms. Experimental studies in monkeys have added laboratory evidence that endurance exercise inhibits the development of CHD. The questions we need to address are not whether exercise is a real element for cardiovascular health, but what kind of exercise is needed, and how much, i.e., with what frequency, intensity, timing, and duration. An understanding of the ways and means by which exercise alters CHD risk is only beginning to emerge, but there is wide acceptance that its benefits are vitally needed in the sedentary Western world.

Exercise-induced changes in plasma lipids and lipoproteins

Men and women who participate in vigorous endurance-type exercise generally have plasma lipid and lipoprotein profiles consistent with lower risk for coronary heart disease. The major differences from matched physically inactive controls appear to be a lower plasma triglyceride concentration and greater high-density lipoprotein mass, due to increased levels of the subfraction HDL2 and apoprotein A-I. Plasma low-density lipoprotein cholesterol concentration is less likely to be lower than in the inactive controls. Exercise training studies suggest a lower threshold--of around 1,000 kcal per week of endurance-type exercise at moderate intensity--seems to be required to produce plasma lipid or lipoprotein changes. Above this level, dose-response relationship exists, with greater changes occurring up to an expenditure of 4,500 kcal per week. From the limited data available, it appears more difficult to change the plasma lipoprotein concentration in women by exercise training than in men. Modification of activity of enzymes involved in triglyceride and cholesterol synthesis, transport, and catabolism most likely mediates these exercise-induced changes.

Exercise and risk factors for arteriosclerosis in 42 married couples followed over four years

Forty-two married couples (30-69 years of age) were followed for 4 years with yearly measurements of risk factors for arteriosclerosis. Advice was given concerning relaxed, enjoyable exercise (mainly running at 10-13 km hr-1). Each person served as his own control by comparison of the first and the last yearly status. Both the group of women and the group of men significantly improved (two sided p less than 0.005) their maximum oxygen uptake, and reduced their blood glucose concentration (two-sided p less than 0.01). S-cholesterol (for the group of men) was reduced statistically significantly (two-sided p less than 0.01). At the first examination the groups of women and men with the lowest maximum oxygen uptake (group I) had higher average values for risk factors than the more active groups (group II). At the final examination almost all persons had improved their maximum oxygen uptake, so none of the other risk factor differences between groups I and II were statistically significant. Both the women and the men improved their well being and their health profile as evaluated in terms of risk factors for arteriosclerosis. Exhaustive exercise was not necessary for beneficial effects.

Exercise and heart disease. Epidemiology of the "exercise hypothesis"

The "exercise hypothesis" states that exercise protects against coronary heart disease. Reviewed herein is the epidemiologic evidence for and against the "exercise hypothesis." The weight of evidence supports the view that exercisers have a lower risk of coronary disease, but that vigorous exercise cannot always prevent progression of coronary atherosclerosis and does increase the risk of sudden death in persons with advanced coronary atherosclerosis. It is concluded that the "exercise hypothesis" is plausible, even likely, but still unproved.

The effects of vasectomy and exercise on cholesterol levels in rat aortas

The effects of vasectomy and exercise upon esterified, unesterified and total cholesterol in rat aortic tissue was determined. A factorial design with two activity levels (aerobic exercise, sedentary) and three treatments (vasectomy, sham-vasectomy, control) was employed. Vasectomy significantly increased the amount of esterified and total cholesterol in aortic tissue. The vasectomy sedentary group had significantly higher unesterified cholesterol levels than the three exercise groups. Total cholesterol levels were significantly higher for the sedentary groups than the exercise groups. There was no significant difference between exercise and sedentary groups in esterified cholesterol.

Physical fitness programming for health promotion at the worksite

Exercise enthusiasts and health professionals have recommended that physical fitness programs be implemented in the occupational setting. Such programs are promoted on the basis of expected benefits to both the employee and employer. The potential for benefit to the employee seems substantial, since a sizable body of knowledge links regular exercise to improved functional capacity and reduced risk for development of certain chronic diseases. The available literature provides some direct evidence that exercise programs can improve the health status of employee groups. Specifically, programs may generate improvements in cardiorespiratory fitness and cardiovascular health and promote long-term adherence to exercise. The physiological goals can be attained with programs that provide 20-30 min of moderately intense "aerobic" activity 3 or more days per week. Several factors are known to affect adherence of employees to company-sponsored fitness programs. Of particular importance are program leadership, motivational schema, program activities, convenience of participation, and social support. It is recommended that, where feasible, supervisors of employee fitness programs (a) secure professional leadership, (b) provide on-site or other facilities that maximize convenience, (c) allow participation across the widest possible time span, (d) provide programs offering a wide range of activities, (e) attend carefully to evaluation, recognition, and other motivational concerns, and (f) incorporate a comprehensive health promotion perspective.

Aerobic exercise. Can you answer the questions your patients ask?

Aerobic exercise is a dynamic exercise form that has as a goal increased cardiovascular fitness. In addition to its potential for improved cardiovascular health, it may also help prevent hypertension, promote improved psychologic health, and help prevent osteoporosis. Certain conditions are contraindications to the undertaking of an exercise program, and some patients should undergo exercise stress testing before beginning. Dietary changes are probably not necessary for persons beginning moderate exercise programs, but in athletes taking part in strenuous forms of exercise, fluid and electrolyte balance and adequacy of muscle glycogen stores should be considered. Exercise, however, is only one of the factors important in fitness and cardiovascular risk reduction.

Release of prostacyclin in vivo and its role in man

Concentrations of 6-oxo-prostaglandin F1 alpha (6-oxo-PGF1 alpha), the stable hydrolysis product of prostacyclin (PGI2) were determined in venous blood sampled from a forearm vein after dextrose (10% w/v) perfusion and after subsequent distension with physiological saline in seven healthy volunteers. 6-oxo-PGF1 alpha was measured by gas chromatography/negative ion chemical ionisation mass spectrometry. Local release of PGI2 was demonstrated in six volunteers: in three both stimuli were effective and in three only one stimulus was effective. In seven trained athletes studied before and after vigorous exercise baseline plasma concentrations of 6-oxo-PGF1 alpha were less than 1.3-3.2 pg/ml. The concentration increased after exercise in each subject (mean 10.9 pg/ml; range 5.5-18.2 pg/ml). Mild chemical and mechanical stimuli therefore can cause local production of PGI2 from human blood vessels in vivo.

Exercise testing and training: clinical applications

The application of exercise in clinical cardiology continues to progress because of research findings. Advances have occurred in the applications, methodology and interpretation of exercise testing. Exercise training has been documented to have a place in the primary prevention of coronary heart disease. In regard to cardiac rehabilitation, both early ambulation and early discharge are safe and beneficial in patients with uncomplicated infarction, and a subsequent exercise program is at least as effective as other interventions. High intensity exercise training in the patient with heart disease may be necessary to cause changes in myocardial perfusion and performance, but it carries an increased risk.

Diet and Exercise Programs for Coronary Heart Disease: Better Late Than Never

It makes sense to reduce dietary fat and increase exercise, but scientists can't prove that it reverses atherosclerosis.