Twenty-three percent of adults globally -- and an alarming 80% of adolescents at school -- failed to be as active as they should have been in 2015, according to a new study. The potential health consequences are big, particularly for people who spend more of their day sitting.
Keeping your body stationary for prolonged periods of time can increase your chances of developing a range of diseases, including certain cancers, type 2 diabetes, cardiovascular disease and stroke.
But factoring in one hour of physical activity for each day spent sitting can offset your chances of disease, according to one of four papers that form part of the series
published Wednesday in The Lancet. The findings are the latest in a line of evidence on the dangers of sitting for too long -- but this time, they come along with a solution.
The study found that the health impacts of an eight-hour workday spent bound to a computer or in a car can be alleviated by activities as simple as cycling at speeds of more than 16 kilometers per hour (about 10 mph) or walking briskly at 5.6 kilometers per hour (about 3.5 mph) for more than 60 minutes each day.
The researchers hope this guidance will kick people and governments into action to get populations moving more.
The importance of being active
"Too many people are physically inactive and are spending long periods sitting. ... It needs to be taken much more seriously," said Ulf Ekelund, professor of physical activity and health at the Norwegian School of Sport Sciences, who led one of the studies.
"We showed that you can offset the association between prolonged sitting and mortality," he said, stressing that "physical activity can prevent almost all non-communicable diseases (such as type 2 diabetes and cardiovascular disease)."
The team analyzed data from more than 1 million people in 16 studies, mainly from Western Europe, North America and Australia, to find out how many hours of daily activity could help reduce the increased risk of death that has been linked to extended periods of time spent sitting. Data from other regions of the world were limited.
People who sat for more than eight hours and were active for less than five minutes had a 59% increased risk of death compared with a reference group of people who sat for less than four hours and were active for more than 60 minutes.
But there was some middle ground. "There was a gradient," Ekelund said. "It doesn't mean that doing 30 minutes isn't worth anything. ... It will definitely reduce the risk." But the longer the activity, the better.
Time spent watching television was also analyzed in one subgroup.
"There were similar associations" with TV, Ekelund said. "People should avoid more than two to three hours of TV viewing per day."
He highlighted the worst-case scenario as a lifestyle in which someone drove to work, sat at their desk all day and then spent a few hours of their evening watching TV. "That's a huge amount of sitting time," he said.
The bare minimum
The recommendations made in the study are double the current World Health Organization guidelines, which urge a minimum of 150 physically active minutes each week -- which people still fail to meet. In the United States, just 21% of the population meets the advised minimum, according to the Centers for Disease Control and Prevention.
But Ekelund's team believes the new findings add to the existing guidelines and help tailor advice to people who spend more time sitting.
Additional studies published alongside this one also highlighted that inactivity is a growing global health problem.
"We wanted to show that physical inactivity is one of the greatest public health threats in society," said Pedro Hallal, associate professor in epidemiology at the Federal University of Pelotas in Brazil, chairman of the committee responsible for the studies.
Hallal worked on a series of studies published in 2012
that were the predecessors to the current papers. One study
attributed 5.3 million deaths globally to physical inactivity in 2008 -- more than lives lost to smoking and obesity.
But Hallal said the new studies show that levels of inactivity have not fallen much since then, despite more countries measuring activity in their populations and increased promotion and policies for people to be more active.
"The reality is that physical inactivity rates are not declining worldwide," he said, blaming a lack of funding as one underlying cause.
But investment is worth every penny, he believes. An additional paper published Wednesday found the global cost of the issue to be $67.5 billion worldwide, equal to the the annual GDP of Costa Rica.
Redesigning cities and classes
Hallal recommends three priorities to help solve the problem: improved urban planning to include cycle paths and greater pedestrian access, more integration with health sectors so clinicians ask patients about their activity levels, and legislation and investment to increase physical education in schools.
If children become used to exercising three or more times a week at school, they are "much more likely to be active throughout their lives," Hallal said.
He added that "there's no other way" and hopes people watching the Rio Olympics over the next few weeks will be motivated to make a change.
The 2012 and 2016 studies were timed to highlight the problem ahead of each of the quadrennial Games.
"Everyone around the world will be thinking about human movement," Hallal said. "This is the moment to show people the importance of being active."