Benefits and Recommendations for Physical Activity

by

John Nicolas

Healthy persons as well as many persons with cardiovascular disease, including those with heart failure, can improve exercise performance with training. This improvement is the result of increased ability to use oxygen to derive energy for work. Exercise training increases maximum ventilatory oxygen uptake by increasing both maximum cardiac output (the volume of blood ejected by the heart per minute, which determines the amount of blood delivered to the exercising muscles) and the ability of muscles to extract and use oxygen from blood. Beneficial changes in hemodynamic, hormonal, metabolic, neurological, and respiratory function also occur with increased exercise capacity. These changes can also benefit persons with impaired left ventricular function, in whom most adaptations to exercise training appear to be peripheral and may occur with low-intensity exercise.

Exercise training results in decreased myocardial oxygen demands for the same level of external work performed, as demonstrated by a decrease in the product of heart rate systolic arterial blood pressure (an index of myocardial oxygen demand). These changes are also beneficial in persons with coronary artery disease, who after exercise training may attain a higher level of physical work before reaching the level of myocardial oxygen requirement that results in myocardial ischemia.

Exercise training favorably alters lipid and carbohydrate metabolism. The exercise-induced increase in high-density lipoproteins is strongly associated with changes in body weight, and greater increases in high-density lipoproteins have been found in women who exercise at higher levels of recreational running. Regular exercise in overweight women and men enhances the beneficial effect of a low-saturated fat and low-cholesterol diet on blood lipoprotein levels. Endurance training has effects on adipose tissue distribution, and the effect on adipose tissue distribution is likely to be important in reducing cardiovascular risk. Exercise training also has an important effect on insulin sensitivity, and intense endurance training has a highly significant salutary effect on fibrinogen levels of healthy older men. In addition, recent data support the role of physical activity in the prevention and treatment of osteoporosis and certain neoplastic diseases, notably colon cancer.

Developing and maintaining aerobic endurance, joint flexibility, and muscle strength is important in a comprehensive exercise program, especially as people age. Elderly women and men show comparable improvement in exercise training, and adherence to training in the elderly is high. Resistance training exercise alone has only a modest effect on risk factors compared with aerobic endurance training, but it does aid carbohydrate metabolism through the development or maintenance of muscle mass and effects on basal metabolism. Furthermore, resistance training is currently recommended by most health promotion organizations for its effects on maintenance of strength, muscle mass, bone mineral density, functional capacity, and prevention and/or rehabilitation of musculoskeletal problems (eg, low back pain). In the elderly, resistance training is both safe and beneficial in improving flexibility and quality of life. Persons with cardiovascular disease are usually asked to refrain from heavy lifting and forceful isometric exercises, but moderate-intensity dynamic strength training is safe and beneficial in persons at low risk.

Many activities of daily living require more arm work than leg work. Therefore, persons with coronary artery disease are advised to use their arms as well as their legs in exercise training. The arms respond like the legs to exercise training both quantitatively and qualitatively, although ventilatory oxygen uptake is less with arm ergometry. Although peak heart rates are similar with arm and leg exercise, heart rate and blood pressure response during arm exercise is higher than leg exercise at any submaximal work rate. Therefore, target heart rates are designated 10 beats per minute lower for arm training than for leg training. Dynamic arm ergometry is usually well tolerated by persons with coronary artery disease; however, there may be an increase in blood pressure that may be of concern in certain persons.

Maximum ventilatory oxygen uptake drops 5% to 15% per decade between the ages of 20 and 80, and a lifetime of dynamic exercise maintains an individual’s ventilatory oxygen uptake at a level higher than that expected for any given age. The rate of decline in oxygen uptake is directly related to maintenance of physical activity level, emphasizing the importance of physical activity.

Middle-aged men and women who work in physically demanding jobs or perform moderate to strenuous recreational activities have fewer manifestations of coronary artery disease than their less active peers. Meta-analysis studies of clinical trials reveal that medically prescribed and supervised exercise can reduce mortality rates of persons with coronary artery disease.

In addition to the physical benefits of exercise, both short-term exercise and long-term aerobic exercise training are associated with improvements in various indexes of psychological functioning. Cross-sectional studies reveal that, compared with sedentary individuals, active persons are more likely to be better adjusted, to perform better on tests of cognitive functioning, to exhibit reduced cardiovascular responses to stress, and to report fewer symptoms of anxiety and depression. In one report69 persons who increased their activity levels between 1965 and 1974 were at no greater risk for depression than those individuals who were active all along; however, persons who were active and became inactive were 1.5 times as likely to become depressed by 1983 compared with those who maintained an active lifestyle.

Longitudinal studies have also documented significant improvement in psychological functioning. Exercise training reduces depression in healthy older men and in persons with cardiac disease or major depression. Exercise also improves self-confidence and self-esteem, attenuates cardiovascular and neurohumoral responses to mental stress, and reduces some type A behaviors. Although exercise training generally has not been found to improve cognitive performance, short bouts of exercise may have short-term facilitative effects.

Despite the positive physical and mental health benefits of exercise, long-term adherence to exercise programs remains problematic. It is estimated that only 50% of all persons who initiate an exercise program will continue the habit for more than 6 months.The issue of nonadherence is particularly important because exercise is only beneficial if it is maintained for extended periods of time. Thus, it is important to develop strategies to improve exercise initiation and adherence, especially for persons who are among the least active”some African-American women, the less educated, the obese, and the elderly.

Healthy persons as well as many persons with cardiovascular disease, including those with heart failure, can improve exercise performance with training. This improvement is the result of increased ability to use oxygen to derive energy for work. Despite the positive

physical and mental health benefits

of exercise, long-term adherence to exercise programs remains problematic.

Article Source:

eArticlesOnline.com

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