Working at a desk all day may not be as bad for your health as sitting in front of a television after work.

That is a finding of a new study done in the United States. It also suggests that not all forms of sitting are equally bad.

Jeanette Garcia led the study. Garcia works as a researcher at the University of Central Florida in Orlando.

An older couple watching television in living room.

"We've been hearing more and more about how sitting is the new smoking," she said. She added that other evidence suggests a relationship between health problems and time spent sitting.

"However, it's been unclear whether all sitting is created equal, suggesting that as long as you reduce any type of sitting, then that's helpful in improving health," she added.

"This study suggests that this may not be the case, and that we should focus more on leisure time sitting, mainly television viewing time, rather than sitting, in general."

The study followed close to 3,600 African-American adults. Almost one-third of them watched television, or TV, for more than four hours a day. A little more than one-third of the subjects spent between two and four hours a day sitting in front of the TV.

The remaining third watched TV for less than two hours a day.

Researchers followed the group for an average of 8.4 years. During the study, 205 of the subjects died and 129 others suffered a heart attack or stroke.

Compared to people who watched less than two hours of television daily, those who spent more than four hours in front of the TV were 49 percent more likely to die or have a heart attack or stroke.

But the undesirable health effects of TV appeared to be limited to adults who failed to get the recommended amount of weekly exercise. That is around 150 minutes of moderate physical activity or 75 minutes of vigorous exercise every week.

The study had some limitations, however.

Lin Yang is a researcher at the University of Calgary in Canada. She says it is possible that sitting in front of the TV might be worse than sitting at a desk because people snack while they are watching TV. Some people simply stay up too late and do not get enough sleep, she wrote in an email.

Eating treats or lack of sleep could both cause weight gain and increase risk factors for heart disease. These factors could make people more likely to die early, she added.

Yang explained that "the evidence on TV viewing and health risks (is) strong," even if the exact biological causes are unclear.

Arch Mainous is a researcher at the University of Florida in Gainesville. Like Yang, he was not involved in the study.

Mainous said in an email that it would be a mistake for people with desk jobs to think there is no need to get moving during the work day.

"Take the stairs rather than the elevator, or take a walk at lunch," Mainous advised. "Leisure time physical activity is definitely beneficial, but working in some more steps in the workday should also be encouraged."

Lisa Rapaport reported on this story for the Reuters news agency. John Russell adapted her story for VOA Learning English. George Grow was the editor.

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