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SPECIFIC CHANGES WITH AGING: CARDIOVASCULAR AND RESPIRATORY SYSTEMS
Our hearts and lungs work together to perform the vital function of making available the oxygen-rich blood that our cells need. The heart must pump blood continuously and at an adequate rate to get blood to our tissues. Our bellows like lungs must fill and empty well enough to cleanse blood of the waste product of metabolism, carbon dioxide, and replenish the needed oxygen. As we grow older both these jobs are gradually performed less efficiently, and this becomes most apparent (and most serious) when we are pushing our bodies to the limit - when we exert ourselves physically.
There is a reduction in what is called \"cardiac output.\'\' Our maximum heart rate during exercise does not get as high, and the volume of blood our heart can deliver per beat declines. The net effect is that our heart cannot circulate as much blood as quickly. This causes a decline in \"maximum oxygen consumption,\" the peak amount of oxygen that can be made available to our cells, so we are increasingly likely to suffer fatigue and have to stop when we push ourselves physically. Our muscles are simply not getting enough oxygen to do their work.
Anatomical changes in our lungs compound the problem. They do not transfer as much oxygen from the outside air to the blood. Beginning at about age forty our \"vital capacity,\" the amount of air we can move in and out of our lungs when we breathe as deeply as we can, gradually declines. By age seventy the loss in vital capacity is estimated to be about 40 percent. Once again, the result is that less oxygen reaches our muscles when they need to work at top capacity, leading to the classic symptoms of growing old - more trouble exerting ourselves, getting \"winded\" more easily, not being able to perform physically as we did before.
Adapting to these changes requires treading a fine line. We have to rearrange our lives to avoid situations beyond our physical limit (accept a friend\'s offer to drive us to the store rather than expecting to still walk the two miles), yet exert ourselves as much as we can. In fact, a major antidote to aging of the heart, and to a lesser extent the lungs, is exertion itself - that is, exercise.
Two decades of research have demonstrated that continuous exercise can have a dramatic effect on cardiovascular functioning. For instance, when researchers compared a group of middle-aged athletes who had stopped exercising with another group who had followed a regular exercise program over thirteen years, the first group showed the normal age-related decline in maximum oxygen consumption. The second group, however, actually showed increases in capacity over the years.
In other words, having once been physically active does not help much in staving off aging, but becoming and staying active in our middle (and later) years not only slows down normal aging losses in this critical area but may even make us more fit than in our younger years.
Even though we are less able to slow normal aging in vision and hearing by changing our life-style, how we handle the small losses that occur in our senses as we age can affect the quality of our life just as dramatically.
*7/159/5*
GENERAL HEALTH
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