July 25, 2005

Aerobic fitness declines rapidly in old age

By Amy Norton

NEW YORK (Reuters Health) - Physical fitness is known to
wane with age, but a study published Monday shows that the
decline gains speed with each decade, regardless of a person's
exercise habits.

The study of 810 healthy adults found that the rate of
decline in aerobic fitness was about four times greater among
people in their 70s or older, compared with those in their 20s
and 30s.

Despite the fact that it boosts aerobic fitness, regular
exercise did not change a person's rate of age-related decline.

However, that does not mean it's time to retire those
running shoes, according to the study authors.

At any given age, people who were at least moderately
active were more fit than their sedentary peers, said lead
author Dr. Jerome L. Fleg of the National Heart, Lung, and
Blood Institute in Bethesda, Maryland.

In addition, he told Reuters Health, research shows that
older people can improve their aerobic capacity by getting
regular, moderate exercise like walking. The point, according
to Fleg, is to help elderly people stay fit enough to perform
daily activities -- like housework or yard work -- and maintain
their independence as long as possible.

Fleg and his colleagues at the National Institutes of
Health report their findings in Circulation, a medical journal
published by the American Heart Association.

The study looked at changes over time in individuals'
VO2max, a measure of aerobic fitness that refers to how much
oxygen the body uses during a given activity. The VO2max is the
point at which the body can no longer ramp up its oxygen use to
keep up with the intensity of the exercise, and the activity
rapidly becomes unsustainable.

It's well known that a person's VO2max declines with age.
But the rate of that decline, Fleg explained, has not been
clear-in large part because studies on the subject have
typically compared different age groups rather than following
the same people over time.

His team's study included healthy men and women between the
ages of 21 and 96 who periodically underwent treadmill tests to
gauge their VO2max. The researchers also charted changes in
participants' blood pressure, body composition and lifestyle
habits, over an average of eight years of follow-up.

In general, the study found, VO2max declined by 3 to 6
percent per decade while people were in their 20s and 30s. The
rate of decline increased with age, going above 20 percent per
decade among adults in their 70s or older.

The "good news," Fleg said, is that active people
maintained a higher VO2max than sedentary people their age,
pointing to the importance of staying active throughout life.

He noted that older, sedentary adults who want to boost
their fitness should consult their doctors before starting to
exercise, as should anyone with heart disease.

SOURCE: Circulation, August 2, 2005.