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Older Exercisers May Benefit From Less-Intense Workouts
By Ira Dreyfuss,
Star-Telegram
March
17, 2003
For
older exercisers, effort counts.
At
least that's what a large Harvard study of heart disease in older men
shows.
It
found that those who thought their workouts were hard had a lower risk of
coronary heart disease, even though the amount of energy they burned was
below minimum federal guidelines.
"Are
they getting any benefit? The bottom line is yes, they are," said
researcher I-Min Lee of the Harvard School of Public Health. Even though
the study involved only men, Lee said the study could be applied to women
as well.
The
study suggests that older people may be able to do less exercise and get
heart health benefits -- provided they feel they are working hard. The
findings were published in February in the American Heart Association
journal Circulation.
Researchers
looked at 7,337 men in the long-running Harvard Alumni Health study. The
scientists examined questionnaires from 1988-95 from men who had an
average age of 66. In the study period, 551 developed coronary heart
disease, a narrowing of the small blood vessels that feed the heart.
In
the questionnaires, the alumni listed their physical activities. The
researchers then estimated how much energy the men probably used in doing
them. Those results were tallied in METs -- multiples of resting metabolic
rate, or the amount of energy a person uses just to sit quietly.
Sitting
quietly is one MET; walking briskly would be about four METs, and jogging
a mile in 12 minutes would be six METs.
The
men rated the difficulty levels of the exercise on a 1-10 scale with 10
being the most difficult.
Researchers
focused on the men whose workouts were at or below three METs, because the
three-to-six-MET range is the minimum energy expenditure that federal
exercise recommendations consider healthful, Lee said.
Looking
at this low-MET group, the scientists compared men whose activities felt
hard to those who felt their activities were easy.
The
ones who rated their intensity at five on the 10-point scale had a 31
percent lower rate of coronary heart disease than did men who rated their
intensity at 0.5.
"The
ones who felt they were exercising hard did better than ones who felt
nothing," said Lee.
The
results make sense because the cardiovascular system is sensitive to
increased effort, said scientist William Haskell of Stanford University,
who was not part of the research team.
If
a person's fitness level is low at the start, then a strong effort can
create a training effect, he said. Training that feels hard can be enough
to increase the heart's ability to pump more blood with each beat, and
also could reduce cholesterol levels, he said.
Lee
said she did the study to see if people who do less than the METs targeted
in the recommendations would still get some benefit. However, neither she
nor Haskell believe people should try to get by on less. For one thing, a
higher metabolic rate means more calories are burned -- and weight can be
lost.
But
current MET standards don't adequately account for the slowing of
metabolism that comes with age, Lee said. The guidelines are based on the
bodies of younger adults who have higher metabolic rates that could run at
three to six METs in moderate exercise, she said.
Lee
said older people would feel they are working just as hard at lower METs.
Although
the science behind the exercise recommendations is based in part on METs,
the guidelines themselves are written in language based on ratings of
perceived exertion. Because people can't keep track of their METs, the
guidelines call for at least moderate exercise for a minimum of 30 minutes
on most days of the week.
Lee
would not change the wording. The recommendations are easy to understand
and widely applicable -- and even older exercisers who won't reach three
to six METs still could find their efforts rewarded, she said.
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© 2002 Global Action on Aging
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