By Lisa Rapaport

(Reuters Health) – Most Americans spend at least two hours a day watching television or videos, and a new study suggests they’re becoming more sedentary as they devote more remaining free time to sitting in front of computers.

Researchers examined data on almost 52,000 people, ages five and up, collected between 2001 and 2016. By the end of the study period, a high proportion of people at all ages spent at least two hours daily sitting watching TV or videos: 62 percent of 5- to 11-year-olds; 59 percent of 12- to 19-year-olds; 62 percent of adults ages 20 to 64; and 84 percent of older adults.

On top of this, the proportion of people in all age groups who spent at least an hour a day on computers outside of work or school also rose. By the end of the study, 56 percent of children and 57 percent of teens spent at least this much leisure time on computers each day, as did half of adults.

“The technology advancement in the modern society shifts the dynamics of household work, transportation, social interaction and the nature of jobs,” said lead study author Lin Yang of the University of Calgary in Canada.

“As our daily life demands less physical activity, we accumulate sedentary time from sitting at school/work, motorized transport, watching TV, computer use and so on,” all of which may be driving recent increases in total sitting time, Yang said by email.

From 2007 to 2016, average daily sitting time for teens increased from 7 to 8.2 hours, researchers report in JAMA. Total sitting time for adults rose from 5.5 to 6.4 hours.

These substantial increases in sitting time are likely due to activities other than television or video watching, and appear closely linked to increased computer use.

Across all age groups, men, black people, obese individuals and physically inactive people were more likely to spend lots of time watching television and videos.

The study wasn’t a controlled experiment designed to prove whether or how sitting time might directly impact health outcomes.

Limitations include its reliance on survey participants to accurately recall and report on how much time they spent engaged in various sedentary pursuits. Researchers also lacked data on how much time people spent on smartphones and tablets.

“We have come to rely on computers and smartphones for many aspects of life from information to entertainment to social interactions,” said Arch Mainous, a researcher at the University of Florida in Gainesville who wasn’t involved in the study.

“It is important to remember that our society has positively viewed most labor saving devices like microwave ovens, washing machines and fast food restaurants as ways to save time that can be devoted to leisure time,” Mainous said by email.

“With much work being done at a desk in front of a computer and numerous labor saving devices that provide more leisure time, it is incumbent on everyone to try and work some activity into their day,” Mainous advised.

Any activity, for any length of time, is going to give people more health benefits than sitting on the couch, said Keith Diaz, a researcher at Columbia University Medical Center in New York City who wasn’t involved in the study.

“Too much sitting time can increase a person’s risk for diabetes, heart disease, and early death,” Diaz said by email. “If you have a job or lifestyle that involves a lot of sitting, you can lower your risk of early death by moving more often, for as long as you want and as your ability allows – the key is to just get moving in any way that you can.”

SOURCE: JAMA, online April 23, 2019.