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."
