Sunday, January 15, 2006

exercise

Until recent years there was little positive scientific proof that exercise had any great effect on aging or its underlying biological processes. The most affirmative idea about exercise was the observation of many physicians that it made people' 'feel better," a respectable judgment even though it rested on clinical observation rather than surveyor experimental evidence.
Until recently scientific research focused primarily on the decline of physical capacity as age advanced rather than any positive benefits of efforts to maintain capacity. The typical research study compared the young and the old, and showed, for example, that young men could achieve a heart rate of 200 beats per minute compared to a maximum of 70 to 90 beats for men aged 70 to 90. The question of whether it might be good for the older men to raise their heart beats to these or any other levels got little attention. Today studies of aging increasingly ask questions phrased in this fashion: does exercise have any direct and measurable effect on physiological, neurological, and endocrine factors that underlie the process of aging? Can exercise improve physical capacity, bone strength, heart function, oxygen uptake and use, mental function, and possibly even personality processes? Can exercise retard the onset of typical indicators of age, and can it moderate their effects and perhaps reverse them? These are bold and challenging questions that are beginning to receive affirmative answers.
One interesting and somewhat exotic piece of research of this kind concerned the cardiovascular adjustments and maximum oxygen consumption of Somali herdsmen engaged in long-distance running. The subjects were 15 male tribe members between 14 and 64 years of age. Many of the members of the tribe outperformed athletes of Olympic standards. Balanced and sustained physical training allows adults such as these to make the best use of their physical abilities. Sustained exercise also prevents the accumulation of fatty deposits during adulthood and helps decrease the cholesterol level. Even these elderly herdsmen, with their high caloric and fat intake, did not have elevated serum cholesterol levels. Furthermore, their body weight and beta-lipoprotein levels did not increase significantly with age. There was a moderate rise in blood pressure in those up to 70 years of age but no signs of clinical symptoms suggestive of ATHEROSCLEROSIS were shown.
Closer to home, the first positive and highly dramatic evidence of the effect of exercise came from a study of 17,000 Harvard graduates published in the New England Journal of Medicine in March 1986. This study showed that death rates were 25 percent to 33 percent lower for men who had engaged in mild as well as strenuous exercise. The specific activities performed by the longer surviving members of the research group included simple walking, climbing stairs, and everyday physical exertions such as that recommended by one exercise physiologist- carrying a bag of groceries from the car into the house from time to time -- as well as more strenuous aerobic exertions. While current research confirms the positive benefits of exercise, experts strongly caution against unwise and suddenly instituted, stressful regimens. The body's physical capacities do in fact decline with age, and sudden deaths like that of runner Jim Fixx can occur. Strenuous aerobics programs popularized by actress Jane Fonda are unsuitable for those who have not maintained or do not enjoy good physical condition. Walking, gentle stretching, and bending typical of Yoga style exercises, and ordinary physical activity all have value. Any decisions to start a new exercise program should, like dieting, include prior consultation with a physician.
Russell, C. H. Good News About Aging. New York: John Wiley and Sons, 1989.

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