Ability to complete
quarter-mile walk a powerful predictor of health outcomes in
elderly
Walking fitness makes a
significant difference in predicting the likelihood of
future disability in the elderly, according to a study
published today in the Journal of the American Medical
Association.
Researchers at the University
of Pittsburgh Graduate School of Public Health (GSPH) and
their collaborators found that the ability to walk
400-meters, or about a quarter mile, was an important
determinant not only of whether elderly participants would
be alive six years later but also how much illness and
disability they would experience within that time frame.
"The ability to complete this
walk was a powerful predictor of health outcomes. In fact,
we found that the people who could not complete the walk
were at an extremely high risk of later disability and
death," said lead author, Anne B. Newman, M.D., M.P.H.,
professor of epidemiology at GSPH and professor of medicine
in the department of medicine, University of Pittsburgh
School of Medicine.
Dr. Newman and her co-workers,
collaborating with researchers at five other institutions,
asked a group of almost 2,700 community-dwelling white and
African-American men and women aged 70 to 79 to complete, as
quickly as they could--without running--and at a consistent
pace, ten 40-meter laps in a corridor. All of the
participants previously had reported no difficulty walking a
quarter of a mile, climbing one flight of stairs without
resting or performing basic activities of daily living.
Participants were excluded from attempting the walk if they
had an abnormal electrocardiogram, elevated blood pressure
or resting heart rate or recently had a procedure for, or
symptoms of, heart disease. Those participants who qualified
for the quarter-mile walk were told to stop if they
experienced any signs of fatigue or persistent rapid heart
rate.
Of the 2,680 elderly people
eligible for the test, 2,324 (86 percent) completed the full
400-meters, while 356 (13 percent) did not complete the
test. The investigators followed the medical histories of
all participants--whether they completed the walk or
not--for about six years.
Among those excluded from or
who stopped the walk, death rates were significantly higher
six years later than those who completed the walk. In
addition, of the more than 2,200 participants who did not
have a clinical diagnosis of cardiovascular disease at the
time of the test, those who did not complete the walk had
significantly more heart-related incidents six years later
compared to those who did. The former group also had a
significantly higher risk of persistent limitations in their
mobility and related disabilities than did those who
completed the full 400-meters.
"A significant portion of
people in the study could not complete the walk, even though
they believed they were in fairly good health. Moreover,
there was a big gap in health outcomes between people who
could complete the longer walk and people who could not,
with the latter being at an extremely high risk of becoming
disabled or dying. What was really surprising is that these
people were not aware of how limited they actually were,"
explained Dr. Newman, who also is a collaborator with the
University of Pittsburgh Institute on Aging.
Even among those who completed
the walk, those in the slowest 25 percent for walk time had
a three- to four-fold higher risk of death than those in the
fastest 25 percent for walk time. Those in the slowest 25
percent of walk time also had a higher risk of
cardiovascular disease-related complications and limitation
in their mobility and mobility-related disabilities than
those in the fastest 25 percent.
Based on these results, Dr.
Newman and her collaborators believe the 400-meter
long-distance corridor walk offers a relatively simple but
powerful way to discriminate levels of function,
particularly among the elderly with normal performances on
lower extremity tests or on short walking tests. More
importantly, it can point out who needs intervention.
"Our study found that many
people who performed well on lower extremity tests or short
walking tests did not perform well on the 400-meter walking
test. Although quite simple, the 400-meter walk appears to
be a highly accurate way to predict whether or not someone
may be experiencing early problems and needs an immediate
referral into an intervention program to help them increase
their activity and physical stamina," she explained.
Unfortunately, many communities
have structural barriers that prevent the elderly from
maintaining physical fitness, so these findings have public
policy as well as public health implications, said the
authors.
According to Dr. Newman, it is
difficult for many older people to find safe places to walk,
and many can't afford indoor exercise equipment, such as
treadmills. As a result, the elderly tend to become more and
more sedentary as they grow older, setting them up for major
problems as they age.
"Individuals who remain
physically active into their 70s have a big advantage in
their 80s in terms of living longer and reducing their risk
of cardiovascular disease and disability. So, we really need
to focus on developing programs in the community that will
help the elderly stay active and healthier longer," she
said.
