Muscle Loss with Aging
As you age, it takes more effort and time to walk up
stairs, mow the lawn, fix a faucet or wash the dishes. Tasks that
you did without effort when you were younger can become major
ordeals that leave you exhausted when you are older. Dr.
Jerome Fleg, a cardiologist at the National Heart, Lung, and
Blood Institute, tested 800 men and women over several years
and found that their ability to sustain exercise decreased rapidly
as they aged. The older they became the faster they lost what
researchers call aerobic capacity (Circulation, July 26, 2005).
Aerobic capacity is a measure of your ability to use
oxygen to do work. If your body can process more oxygen than
that of another person, usually you will be able to run faster, walk
or work longer, and have more energy than that person. The
men and women lost three to six percent per decade in their 20's
and 30's , and 20 percent per decade in their 70's. The men lost
aerobic capacity faster than the women. The men lost 8.3
percent of aerobic capacity in their 40's and 23 percent per
decade in their 70's.
This study was done with people who were healthy
enough for vigorous exercise on a treadmill that measured their
exercise capacity. People who have had heart attacks, strokes,
diabetes or other wasting diseases would lose aerobic capacity
much faster than healthy people. The results showed that a
regular exercise program can increase exercise capacity by up to
25 percent, which would give the older participants the same
exercise capacity as you would expect in people who are twenty
years younger.
The loss of aerobic capacity with aging explains why
older people cannot compete effectively against younger ones in
endurance events. The good news is that a regular exercise
program can increase your maximum heart rate. By exercising
regularly and vigorously, your will develop stronger skeletal
muscles. When you contract your leg muscles, they squeeze
against the veins in your legs and pump blood toward your heart.
When your leg muscles relax, the veins dilate and fill with blood.
This alternate contacting and relaxing pumps extra blood toward
your heart. The extra blood returned to the heart stretches and
strengthens the heart muscle, causing it to beat faster and with
more force. So strengthening your leg muscles increases your
maximum heart rate, even as you age.
Checked 7/8/08