CAUSES OF AGING
Physical Activity and Aging
Decreases in physical activity and accompanying changes
in body composition may cause some of the declines in
body metabolism and cardiovascular function that occur
with advancing age.
In addition, aging produces several changes in the
ability of our body to acquire and deliver oxygen to
the tissues. These changes include increasing stiffness
of the chest wall, impaired
blood flow through the lungs, diminished strength
of each contraction of the heart, and decreased muscle
mass. It is not surprising that because of these
changes the physical work capacity of the average 70-year-old
person is about half that of a 20-year-old. Although
the decrease over this 50-year age span is progressive,
the rate of loss accelerates after our mid-fifties.
Total body
metabolism declines slightly but steadily. The maximum
oxygen consumption with exercise, a measurement of fitness,
declines more rapidly because of the decrease in lean
muscle mass and a fall in maximum heart rate. While
there is considerable variability among older individuals,
the maximum oxygen consumption tends to be higher in
physically active people than in sedentary individuals.
It may be higher still in older athletes who are in
training. Even after correction for height, weight,
and other differences, maximal oxygen consumption is
higher in men than in women.
Regular
physical exercise is the best antidote to many of
the effects of aging. The major benefits from regular
exercise include:
- Favorable effects on fats in the blood
- Better handling of blood sugar
- Increased maximal oxygen capacity
- Greater strength
- Denser bones
- An improved sense of well-being
- Better sleep
It has not yet been proven, however, that an exercise
regimen reduces the chance of eventual disability or
prolongs life expectancy.
Nonetheless, these benefits are likely to be demonstrated
in the next several years as a result of current studies
in aging.
We have just reviewed how aging affects our bodies'
control systems and defense
systems, and that regular physical exercise may
well forestall some of these changes. We must also consider
some of the more
visible manifestations of aging.
Next: The Impact
of Behavioural Elements on Aging
Aging
Causes Index | Why Skin Ages | Behaviour
| Free Radicals | Exercise
| Smoking | Cancer
|
