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Exercise Fails to Help Senior Citizens Maintain
Aerobic Capacity
July 26, 2005 A new study says earlier
assumptions about the rate of decline in aerobic capacity for senior
citizens under-estimated the rate of decline. Their research says the
decline in peak treadmill oxygen consumption accelerates markedly with
each successive decade of age, especially in men, regardless of physical
activity habits. In short: exercise does not appear to slow the loss of
aerobic capacity, which is critical in the ability of older people to
function independently.
The difference in the rate of decline was sharp. In
their 20s and 30s, the rate averaged between three percent and six
percent per decade. When subjects reached their 70s, the decline grew to
20 percent per decade or more.
"This study does not mean that older people can't
improve their fitness," says researcher Jerome L. Fleg, MD, a
cardiologist at the National Heart, Lung, and Blood Institute.
"Over time, your aerobic capacity (exercise
capacity) will decline, but at any given age someone who exercises will
have a higher capacity than someone who is a couch potato," says Fleg.
"By participating in a training program, you can raise your aerobic
capacity 15% to 25%, which in our study would be equivalent to being
10-20 years younger."
"These results are even more striking given that we
were looking at the best-case scenario," says Fleg. "Participants were
required to have no previous heart attack or stroke and to be healthy
and agile enough to walk on the treadmill. The rate of decline in the
population-at-large is probably somewhat greater than what we observed
here, because many older people will have disease-related deficits in
addition to those brought on by age."
I guess we were a little disappointed that regular
exercise didn't make a difference in the rate of decline,' Fleg said.
There was some good news - those who were active ended up in better
condition because the started with higher aerobic capacities to begin
with.
If I start higher, I'm going to end higher, Fleg
said. Having a higher aerobic capacity translates into being more fit.
The bottom line appears to be that those who
exercise regularly are able to handle the tasks of daily life more
easily as they get older. While decline is inevitable, those that are in
better shape to begin with will fare better in the long run.
The ability of older persons to function
independently is dependent largely on the maintenance of sufficient
aerobic capacity and strength to perform daily activities. Although peak
aerobic capacity is widely recognized to decline with age, its rate of
decline has been estimated primarily from cross-sectional studies that
may provide misleading, overly optimistic estimates of aging changes.
To determine longitudinal rate of change in aerobic
capacity and the influence of age, gender, and physical activity on
these changes, we performed serial measurements of peak treadmill oxygen
consumption (peak VO2) in 375 women and 435 men ages 21 to 87 years from
the Baltimore Longitudinal Study of Aging, a community-dwelling cohort
free of clinical heart disease, over a median follow-up period of 7.9
years.
A linear mixed-effects regression model was used to
calculate the predicted longitudinal 10-year rate of change in peak VO2,
expressed in milliliters per minute, for each age decade from the 20s
through the 70s after adjustment for self-reported leisure-time physical
activity.
A longitudinal decline in peak VO2 was observed in
each of the 6 age decades in both sexes; however, the rate of decline
accelerated from 3% to 6% per 10 years in the 20s and 30s to >20% per 10
years in the 70s and beyond.
The rate of decline for each decade was larger in
men than in women from the 40s onward. Similar longitudinal rates of
decline prevailed when peak VO2 was indexed per kilogram of body weight
or per kilogram of fat-free mass and in all quartiles of self-reported
leisure-time physical activity. When the components of peak VO2 were
examined, the rate of longitudinal decline of the oxygen pulse (ie, the
O2 utilization per heart beat) mirrored that of peak VO2, whereas the
longitudinal rate of heart rate decline averaged only 4% to 6% per 10
years, and accelerated only minimally with age.
Conclusions: The longitudinal rate of decline in
peak treadmill oxygen consumption in healthy adults is not constant
across the age span in healthy persons, as assumed by cross-sectional
studies, but accelerates markedly with each successive age decade,
especially in men, regardless of physical activity habits. The
accelerated rate of decline of peak aerobic capacity has substantial
implications with regard to functional independence and quality of life,
not only in healthy older persons, but particularly when disease-related
deficits are superimposed.
About the study
Jerome L. Fleg MD*, Christopher H.
Morrell PhD, Angelo G. Bos MD, PhD, Larry J. Brant PhD, Laura A. Talbot
RN, PhD, Jeanette G. Wright , and Edward G. Lakatta MD
From the Laboratory of
Cardiovascular Science (J.L.F., C.H.M., J.G.W., E.G.L.) and Laboratory
of Clinical Investigation (A.G.B.) and Research Resources Branch (L.J.B.),
Gerontology Research Center, National Institute on Aging, National
Institutes of Health, Baltimore, Md; the Mathematical Sciences
Department, Loyola College in Maryland, Baltimore, Md (C.H.M.); and the
Graduate School of Nursing, Uniformed Services University of the Health
Sciences, Bethesda, Md (L.A.T.).
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