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 The study involved more than 17,700 women with an average age of 72
who were asked to wear accelerometers every day for a week.
Researchers followed the participants for more than two years on
average. During this time, 207 women died.
When the researchers sorted women into four groups from most to
least active, they found those who got the most moderate to vigorous
physical activity, such as brisk walking, were up to 70% less likely
to die during the study period. Getting more low-intensity activity,
however, didn’t appear to influence the odds of death.
“The fact that physical activity lowers the risk of premature
mortality is not a new fact - we have many studies showing this,”
said lead study author I-Min Lee of Harvard Medical School and
Brigham and Women’s Hospital in Boston.
“However, previous studies have primarily relied on self-reported
physical activity, and self-reports tend to be imprecise,” Lee said
by email.
Earlier studies based on participants’ own assessments of their
activity levels have found regular exercise associated with up to
about a 30% reduction in mortality rates, Lee and colleagues note
online November 6 in Circulation.
Accelerometers and other activity trackers are more reliable ways to
examine the connection between longevity and exercise habits because
they offer a more accurate picture of how much time people devote to
exercise as well as how hard they work out and how much time they’re
sedentary in a typical day.
The accelerometers used in the current study could measure activity
along three planes: up and down, front to back and side-to-side.
This can help researchers see not just if people are moving, but the
intensity of their movements.
Half of the participants spent at least 28 minutes in moderate to
vigorous physical activity on an average day, or around 196 minutes
a week.
Doctors typically advise people to get at least 150 minutes a week
of moderate to vigorous exercise.
Even though some previous research has linked excessive sedentary
time to a higher risk of premature death, the current study didn’t
find an association between these two things.
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One limitation of the study is that researchers didn’t follow women
for very many years, which might make it hard to see long-term
benefits of intense exercise for older women. In addition, even
though researchers accounted for individual characteristics and
medical issues, they relied on women to report their own health
problems and this may have allowed some inaccurate or incomplete
information to be used in the analysis.
It’s also possible that the study results might not reflect what
would happen for all older adults because these participants were
avid exercisers, said Dr. David Alter, a researcher at the
University of Toronto who wasn’t involved in the study.
“This study examined a healthy active group of women where we might
have not expected to see any deleterious effects from sedentary
behavior,” Alter said by email. “Had the researchers explored very
sedentary non-exercise avid individuals, the results might have been
(different).”
Even so, the findings add to a large body of evidence already
linking moderate to vigorous physical activity to a lower risk of
premature death, said Keith Diaz, a researcher at Columbia
University Medical Center in New York who wasn’t involved in the
study.
“Research shows individuals have a hard time estimating how many
hours a day they are active or sitting,” Diaz said by email. “So
what's relatively new about this study is that an activity monitor
was used to more accurately determine how much time study
participants spent active and sitting.”
Anyone who can’t handle a brisk walk every day can consider other
options to get the benefits of moderate to vigorous physical
activity, Diaz added.
“Swimming, bicycling, rowing, arm cycling, and seated steppers are
all alternatives,” Diaz said.
SOURCE: http://bit.ly/2znGTYd
Circulation 2017.
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