Published August 24, 2026 08:26AM<\/p>\n<\/div>\n
Back in 2014, I wrote an article describing sitting as \u201cthe new smoking<\/a>.\u201d In my defense, I intended the phrase to be read in air quotes\u2014even at the time, it seemed a bit hyperbolic. In the years since then, the panic over the health dangers of uninterrupted sitting time has receded. The science hasn\u2019t really changed though. There\u2019s still evidence that being stapled to your office chair all day is bad for you, in ways that even the most rigorous exercise routine might not be able to erase.<\/p>\n It\u2019s that last part that remains controversial: the idea that sitting for ten hours is bad even if you, say, ran for two hours that morning. Over the years, studies have seesawed back and forth on the question of whether sufficient exercise is enough to erase the hazards of excessive sedentary time. In an upcoming issue of the journal Medicine & Science in Sports & Exercise<\/i>, the two sides square off in a formal point<\/a>\u2013counterpoint<\/a>\u2013rebuttal<\/a>\u2013counter-rebuttal<\/a> debate.<\/p>\n <\/p>\n Sign up for a ten-part email series from Alex Hutchinson on how to train, fuel, and recover. Each week, Alex covers a new topic, including strength training, supplements, and more!<\/p>\n <\/section>\n The claim to be debated is \u201cPhysical Activity Fully Offsets the Health Risks of Sedentary Behavior.\u201d Here are some of the key arguments.<\/p>\n The case in favor of exercise was authored by Ulf Ekelund and his colleagues at the Norwegian School of Sports Science and the Norwegian Institute of Public Health in Oslo. The crux of their argument is, essentially, \u201cCheck the data.\u201d<\/p>\n Large long-term studies have found that the more hours per day you spend sitting, the more likely you are to develop conditions such as heart disease and, eventually, to die prematurely. The key question is whether eight hours of sitting per day is equally bad for someone who does no exercise, someone who does a bit of exercise, and someone who does a lot of exercise.<\/p>\n Early studies suggested that exercise provided partial but not complete protection from the ravages of sitting. But Ekelund and his colleagues aren\u2019t convinced by the data or the statistical methods of these studies. When they aggregated data from 16 studies with more than a million subjects, they reached a different conclusion, as shown in the following graph:<\/p>\n It\u2019s a complicated figure, but it\u2019s worth taking a moment to parse it. Hazard ratio, on the vertical axis, is an estimate of how likely you are to die during the study period. A hazard ratio of 1.1 basically means that you\u2019re 10 percent more likely to die compared to the reference group.<\/p>\n The subjects are split into four groups of four. The group on the far left is the heavy exercisers: they get more than 35.5 MET-hours per week of physical activity, which works out to 60 to 75 minutes of moderate exercise per day. The group on the far right is the non-exercisers, getting less than 2.5 MET-hours per week, or less than five minutes per day.<\/p>\n Within each group, they\u2019re divided based on how much time they spend sitting, from less than four hours per day to more than eight hours. As you\u2019d expect, the hazard ratio within each exercise group<\/i> generally increases with sitting time. Check out the non-exercisers on the far right: those who sit the least have a hazard ratio of 1.2, while those who sit the most are up near 1.6. That\u2019s a big difference.<\/p>\n But look more closely at the heavy exercisers on the left. Those who sit less than four hours per day are the reference group, with a hazard ratio of 1.0. But those who sit more aren\u2019t noticeably worse off. Even those sitting more than eight hours a day have a modest hazard ratio of around 1.05 with an error bar that passes through the 1.0 line, meaning that there\u2019s no statistically significant increase in risk from sitting for more than eight hours a day.<\/p>\n QED, according to Ekelund.<\/p>\n Strangely enough, the crux of the counterargument, as articulated by a group led by Paddy Dempsey of Deakin University in Australia, is also \u201cCheck the data.\u201d<\/p>\n Ekelund\u2019s million-subject meta-analysis, for example, relies on self-reported exercise and sitting data, which is notoriously inaccurate. Using objective data collected by wearable accelerometers produces a different outcome in at least some studies, with the harm of excessive sitting not completely eliminated by lots of exercise.<\/p>\n And even if you look back at Ekelund\u2019s data above, you can\u2019t help thinking that the hazard ratios are trending upward with increased sitting. The effect may not be statistically significant at eight hours, but what about ten? Or twelve?<\/p>\n Dempsey and co. have several other lines of argument. One that I don\u2019t find convincing is \u201cdose realism,\u201d which points out that even if it\u2019s theoretically<\/i> possible to wipe out ills of sitting with exercise, very few people are actually capable of doing and\/or willing to do that much exercise. That may be true, but I\u2019m still interested in knowing whether it\u2019s possible\u2014because if it is, I want to be one of the happy few who does it!<\/p>\n A more convincing point, to me, is the question of physiological plausibility. Or to put it another way, is the problem with sitting merely the absence of exercise? Or does prolonged lack of movement mess up your metabolism in ways that are distinct from the good things that exercise does?<\/p>\n There are various lines of evidence suggesting that the absence of muscle contractions for hours at a time causes damage. For example, the frictional drag of blood rushing through your blood vessels when you move triggers the release of nitric oxide, which helps keep the vessel walls supple and responsive. When you stop moving for hours at a time, the absence of this signal leaves your vessel walls stiffer, which over the long term can predispose you to heart disease.<\/p>\n Another sign that sedentary time directly causes damage is the phenomenon of \u201cexercise resistance<\/a>.\u201d Normally exercise produces a bunch of immediate metabolic benefits: better insulin sensitivity, higher glucose tolerance, lower triglycerides. But if you\u2019re completely sedentary for a few days, then the measurable metabolic benefits of the exact same workout are blunted.<\/p>\n This is one of those debates where I finished reading each side thinking, \u201cHmm, this sounds pretty convincing, I guess they\u2019re right.\u201d In other words, there simply isn\u2019t enough data at this point to definitively pick a side.<\/p>\n From a theoretical perspective, I find the \u201cphysiological plausibility\u201d argument powerful. Sitting isn\u2019t bad merely because you\u2019re not moving around and thus missing out on an opportunity to get fitter; it\u2019s bad because negative things are happening inside your body.<\/p>\n In that sense, saying that exercise can cancel out the negative effects of sitting is like claiming that eating sufficient broccoli will cancel out the negative effects of ice cream. In reality, no matter how much broccoli you eat, you\u2019re still better off eating less ice cream. (Don\u2019t take this example too literally: I\u2019m with Don Kardong, the Olympic marathoner who famously said: \u201cWithout ice cream there would be darkness and chaos.\u201d)<\/p>\n In practice, is this something to panic about? Do you need to set an alarm to do jumping jacks every 20 minutes for the rest of your waking life? Ekelund\u2019s data reassures me that, with sufficient exercise, which seems to be the equivalent of about an hour of moderate activity per day, it\u2019s not that<\/i> urgent. I have a sit-stand desk, and I generally only raise it a couple of times a day for 10 or 15 minutes, when I notice that my legs are getting stiff. At that point, it actually feels better <\/i>to stand up for a while, so it\u2019s not a burden.<\/p>\n Of course, the reason that my legs are stiff is usually that I\u2019ve done a particularly long or hard run that morning. Ironically, I find it much easier to accidentally stay glued to my office chair for hours on end when I\u2019m not doing much training. The more sedentary you are, the easier it is to stay sedentary. Maybe that\u2019s a rule of thumb to keep in mind: if getting out of your chair feels like a big hassle, then it\u2019s time to stand up.<\/p>\n For more Sweat Science, sign up for the <\/i>email newsletter<\/i><\/a> and check out my new book <\/i>The Explorer\u2019s Gene: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map<\/a>.<\/i><\/p>\nSweat Science 101<\/h2>\n
Why Exercise Trumps Sitting<\/h2>\n
Why Exercise Doesn\u2019t <\/i>Trump Sitting<\/h2>\n
The Verdict<\/h2>\n