Employees at Opower in Arlington, VA, have the option of using standing desks and even have a treadmill desk. (Dayna Smith/The Washington Post). 
 
 Sitting for eight or more hours a day can be deadly. 
 
 That fact has been hammered home in study after study showing the negative health effects -- including heart disease, poor circulation and joint pain -- associated with being parked on your behind for most of the day. The only sure way to prevent those problems, researchers have said, is to sit far less. 
 
 But there is growing evidence that there are ways to reverse the damage without necessarily committing to being on your feet for eight or more hours a day. 
 
 A new study by researchers at Indiana University published in Medicine & Science in Sports & Exercise suggests that the impaired blood flow in leg arteries can actually be reversed by breaking up your sitting regimen with five-minute walking breaks. 
 
 Sitting can cause blood to pool in the legs and prevent it from effectively flowing to the heart -- a precursor to cardiovascular problems. After just one hour of sitting, normal blood flow became impaired by as much as 50 percent, the study found. 
 
 But the men who walked for five minutes on a treadmill for each hour they sat didn't see that decline. 
 
 "American adults sit for approximately eight hours a day," Saurabh Thosar, the study's lead author, said in a statement. "The impairment in endothelial function is significant after just one hour of sitting. It is interesting to see that light physical activity can help in preventing this impairment." 
 
 The findings add to a growing body of evidence that all is not lost for people unwilling or unable to get on the standing desk train or those who can't do much about long commutes. It is also the first experimental evidence that moderate movement can promote healthy blood flow, in spite of sitting habits. 
 
 Participants in the study were otherwise healthy males between the ages of 20 and 35 who did not have any heath problems like obesity, heart disease, high blood pressure or diabetes. 
 
 "They were inactive people though; they did not exercise regularly,” Thosar said in an interview. “There is a risk that people who don’t exercise can start sitting more and more. That’s why we chose that population.” 
 
 Going to the gym isn't likely to reverse the damage caused by sitting all day (one study found that six hours of sitting counteracted the positive health benefits of an hour of exercise). But several studies suggest that simply breaking up bouts of sitting with moderate exercise or movement can have a positive impact. 
 
 One study earlier this year found that breaking up prolonged sitting with light or moderate walking breaks reduced the blood pressure of a group of obese adults in a randomized trial. And yet another recent study found that breaking up sitting with light activity improved blood sugar levels, but breaking up sitting with bouts of standing did not. 
 
 Thosar's study did not investigate whether walking proved more effective than standing when it came to improving blood flow. But he suspects that walking prevented impaired blood flow in the legs because it requires active muscle movement. 
 
 "Walking definitely increases blood flow in the legs," added Thosar, who is now a researcher with Oregon Health & Science University. "If it's static and people are not moving, perhaps people are still not using their muscles as much as during walking." 
 
 (Disclaimer: The author of this story recently began using a standing desk, which raised eyebrows throughout The Washington Post newsroom.) 
 
 [This post has been updated.] ||||| There’s been a lot of finger-wagging of late about the health risks associated with sitting at a desk all day, or binge-watching our favorite TV shows. Now couch potatoes can rejoice because a new study has found that just an hour of moderate activity a day wipes out all the negative impacts of sedentary behavior—contrary to some prior studies claiming exercise didn’t help much at all. 
 
 “Our message is a positive one,” lead author Ulf Ekelund, of the Norwegian School of Sports Science and the University of Cambridge, said in a statement. “It is possible to reduce, or even eliminate, these risks if we are active enough, even without having to take up sports or go to the gym.” 
 
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 The study is part of a new four-paper series published today in The Lancet, along with several commentaries, timed to appear just before the start of the Olympic games. That’s not a coincidence. It’s a follow-up to a 2012 series in The Lancet declaring physical inactivity a “global pandemic,” and estimating that 5.3 million people die each year due to inactivity. The 2016 series examines how much progress has been made over the last four years to counter this. [You can listen to a full Lancet podcast about the whole series here.] 
 
 Sitting for long periods—as many of us do for work—and binge-watching TV is the new smoking when it comes to human health risks. Over the last few years, there have been countless studies claiming links between our sedentary lifestyles and heart attacks, kidney diseases, chronic diseases, and colorectal cancer. Others warned that this behavior shortens our life expectancy and gives us mental health issues. And even for those who exercise regularly, a 2014 Mayo Clinic study found that every hour you sit reduces the gains of your daily workout by eight percent. 
 
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 Now for the good news: that last bit might not be true after all. Earlier this year, yet another study, this time by researchers from the University of Leicester, found that people who exercise regularly really do offset the unhealthy side effects of sitting all day. And the latest meta-analysis published today in The Lancet supports that conclusion. 
 
 Granted, an hour a day of moderate exercise is twice the amount of exercise recommended by the current World Health Organization (WHO) guidelines. Even 30 minutes a day can be beneficial, but if you really want to offset all that sitting and binge-watching, the researchers agreed that you’ll need to double that. This doesn’t mean intense gym workouts or hardcore training for marathons. Anything that boosts your heart rate qualifies, including a nice brisk walk to work or leisurely bike ride. 
 
 Bear in mind that this is a meta-analysis of prior research. According to Ekelund, he and his colleagues first combed through the existing scientific literature and picked out 13 studies relating to how much time people spend sitting and mortality (defined as premature death). Then they contacted the original authors and asked them all to reanalyze their data using the same parameters. This gave them a huge sample size: over 1 million subjects in all. 
 
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 Ekelund and his colleagues divided the subjects into four equal groups, based on their level of physical activity—anywhere from less than 5 minutes a day, to an hour or more per day (60-70 minutes, on average). They found that those who were sedentary for eight hours a day, yet countered this with an hour of physical activity, had a much lower risk than those who maybe didn’t sit for as long a period, but were not as physically active. That suggests it’s not the sitting, it’s the exercise that is the most relevant factor. (Needless to say, people who sat the most and exercised the least had the highest risk.) 
 
 So what about binge-watching our favorite TV shows, which can be an even more passive activity than sitting at a computer typing? There have been a lot of hysterical headlines in recent years about how watching too much TV is totally going to kill you. 
 
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 There’s some grounds for the concerns. A 2014 Spanish study found that if you’re watching three or more hours per day, you’re twice as likely to die in the next few years. Sitting in front of the TV has also been linked to higher risk of colon and lung cancers. Just this week, yet another study appeared warning about the dangers of excessive binge-watching—this time showing an increased risk of dying from a blood clot in the lungs among the Japanese subjects. 
 
 
 
 More good news: An hour of exercise a day also helps reduce this risk, according to Ekelund, although the beneficial impact is not quite as strong. He attributes the difference to what he calls “residual confounding”—that is, other factors are likely influencing the outcome of the analysis. Some people might have a more unhealthy lifestyle overall, or perhaps we snack or drink more while watching TV, all of which could adversely impact our health. 
 
 As for those who might protest that an hour a day of moderate exercise just isn’t reasonable for very busy people, Ekelund pointed out in a London press conference earlier today that the average amount of time adults in the United Kingdom spend watching TV is 3 hours and 6 minutes. “I don’t know if it’s too much to ask that maybe a little of those three hours be devoted to physical activity,” he said. The general rule of thumb, as Ekelund succinctly advised: “Sit less and move more, and the more the better.” 
 
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 [The Lancet]
– It's a wonder anyone dares sit anymore, considering the avalanche of recent studies that have been telling us that doing so ups our risk of cancer and heart disease, makes us fatter, and turns meetings into awful experiences. And here's a new one to add to the pile: Sitting for three hours a day can take two years off of your life, reports the Wall Street Journal—even if you exercise and eschew smoking, according to a new "meta-analysis" of five studies of 167,000 people. Couch potatoes have it even worse: Watch more than two hours of television a day and subtract another 1.4 years. "Sedentary behavior is something we need to take note of beyond telling people to get 30 minutes of activity a day," says one of the study's authors. "Several studies show that when you're sitting, your leg muscles are completely inactive. When you're sitting and completely inactive, this is when you run into trouble managing blood glucose." You can find the full study at BMJ Open.