GENEVA — As the coronavirus leaves many people housebound and many Americans sit to feast for Thanksgiving, the World Health Organization says people need to get more active, insisting that up to 5 million deaths worldwide could be avoided each year if people would run, walk and simply move more.

The U.N. health agency, launching updated guidelines on physical activity and its first advice on sedentary behavior, is pointing to figures that one in four adults — and four in five adolescents — don’t get enough physical activity, a situation that’s complicated by the COVID-19 crisis that has shut up many people indoors.

It recommends at least 2 1/2 hours of “moderate to vigorous aerobic activity” for adults per week, and an hour per day for kids and teens. A lack of physical activity leads to extra health care costs of $54 billion per year, plus another $14 billion in lost productivity, WHO said.

The findings come as the Geneva-based agency released an update on “WHO Guidelines on physical activity and sedentary behavior” — building upon, revising and expanding recommendations in the previous guidelines published a decade ago.

“Physical activity of any type and any duration can improve health and well-being, but more is always better,” said Dr. Ruediger Krech, WHO’s director of health promotion. “If you must spend a lot of time sitting still, whether at work or school, you should do more physical activity to counter the harmful effects of sedentary behavior.”

“The old adage — prevention is better than cure — really applies here,” Krech said. “WHO urges everyone to continue to stay active through the COVID-19 pandemic. If we do not remain active, we run the risk of creating another pandemic of ill-health as a result of sedentary behavior.”

Dr. Fiona Bull, who heads the physical activity unit at WHO, said the guidelines offer advice on “sedentary behavior” for the first time.

She added that experts previously believed physical activity should be done in blocks of at least 10 minutes. But the increasing use of fitness-monitoring devices has generated new science showing that it’s really most important to get 150 minutes at least per week.

“In fact, that 10-minute minimum is not so important and every move counts,” she said. “It’s the total amount we all achieve: Reaching 150 (minutes) and extending.”

Bull said only 78 countries, based on WHO’s most recent survey, have national guidelines on physical activity. She encouraged nations to leverage the new guidelines “as the basis for fast-tracking their policy development.”

Regular physical activity is important to help prevent heart disease, diabetes and cancer while also reducing symptoms of depression and anxiety, and “boosting brain health,” WHO said. People aged over 65 should focus on balance, coordination and muscle strength to help prevent falls, it said.