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The American Heart Association (AHA) says that too many people are
spending far too much time on chairs and couches. "Based on existing
evidence, we found that U.S. adults are sedentary for about six to eight hours
a day, "said Deborah Rohm Young, chair of AHA panel that wrote the new
advisory.
According to the AHA, growing evidence shows that, on its own, exercise
isn't enough to cancel out the unhealthy effects of sitting for a long time.
"Regardless of how much physical activity someone gets, long sedentary
time could negatively influence the health of your heart and blood
vessels," Young explained.
The exact mechanisms behind the effect aren't yet clear. “There are many
important factors we don't understand about sedentary time yet," Young
said. She stressed that, "the types of studies available identify trends
but don't prove cause and effect.”
"We don't have information about how much sedentary behavior is bad
for health — the best advice at this time is to 'sit less and move more,” she
added.
How much more? According to the AHA, people should try to get at least
30 minutes of moderate to vigorous (剧烈的)exercise a day to reach the recommended 150 minutes
of moderate exercise or 75 minutes of vigorous exercise a week, That's
healthier than trying to cram their weekly exercise into one or two days,
according to the statement.
"The real risk simply comes down to the amount we sit, without
there being a true medicine or method to control the harmful effects," said
Steinbaum, a preventive specialist in heart disease.
Still, society has evolved to encourage sitting, she added.
"Our lives have become focused around activities requiring us to be
still—whether it be
transportation, our computers, or the television or computer in our leisure
time,” Steinbaum said. "Sociologically, instead of being active to be
productive or to have enjoyment, our productivity and fun often requires
minimal physical activities."