More Ev­i­dence That Sit­ting Is Bad For Us— And Ex­er­cise Alone Won’t Save Us


The Amer­i­can Heart As­so­ci­a­tion (AHA) has just re­leased a science ad­vi­sory on the ills of sit­ting. The ex­perts who wrote the re­view sifted through the avail­able ev­i­dence on the risks that lack of ac­tiv­ity con­fers on us. Amer­i­cans, the team finds, sit for six to eight hours a day, on av­er­age, and sit­ting, as a num­ber of stud­ies have found, is linked to all kinds of prob­lems, from di­a­betes to death. But the larger prob­lem is that ex­er­cise alone won’t save us—even peo­ple who work desk jobs but are quite ac­tive in their leisure time don’t have the same re­duced risk of dis­ease and death as peo­ple who sim­ply sit less in the first place. Which makes it hard to de­ter­mine ef­fec­tive ex­er­cise guide­lines. But, as the team con­cludes, per­haps the more ef­fec­tive mes­sage at the mo­ment would be to sit less, in­stead of just ex­er­cise more.

The re­view was writ­ten up by a team at re­search in­sti­tu­tions all over the coun­try, and pub­lished in the AHA jour­nal

The team combed the re­search out there on seden­tary time, ex­er­cise, risk of dis­ease and mor­tal­ity, and found that peo­ple have def­i­nitely got­ten more seden­tary over the years: One study they cite re­ported that the av­er­age time peo­ple in the U.S. spent sit­ting rose from 26 hours/week in 1965 to 38 hours/week in 2009. In the UK, it was slightly higher, ris­ing from 30 hours/week to 42 hours/week, re­spec­tively.

And as ex­pected, sit­ting for long pe­ri­ods of time was linked time and time again to di­a­betes, car­dio­vas­cu­lar risk and death. For in­stance, stud­ies look­ing at the cor­re­la­tion be­tween TV-watch­ing and di­a­betes risk have found that each ad­di­tional two hours of time a per­son spends watch­ing TV is linked to an in­creased risk of di­a­betes by at least 14%, or more. Sim­i­larly, the risk of heart dis­ease rises by around 6-8% for ev­ery ad­di­tional hour a per­son spends watch­ing TV. Fi­nally, peo­ple who are the most seden­tary have a sig­nif­i­cantly-higher risk of mor­tal­ity—some­times by sev­eral times—than those who are the least seden­tary.

The big­ger prob­lem might be that ex­er­cis­ing seems to only par­tially lessen the blow of sit­ting too much. It does not com­pletely re­verse it. That is, even peo­ple with high lev­els of phys­i­cal ac­tiv­ity in their free time, if they sit a lot oth­er­wise, are still at higher risk than peo­ple who sit the least.

So what are we to do? For one, the au­thors say, we should punc­tu­ate our seden­tary times quite in­ten­tion­ally, by pop­ping up and stretch­ing or walk­ing a bit ev­ery 30 min­utes or so. “If you’re al­ready phys­i­cally ac­tive, that’s the most im­por­tant thing. But it’s good to take breaks from seden­tary time, too,” study au­thor Deb­o­rah Rohm Young said in a state­ment. “In­stead of pow­er­ing through your work from the minute you get into the of­fice un­til lunch break, con­sider walk­ing around the of­fice a cou­ple of times.”

She and her team also point out in the ad­vi­sory that ask­ing peo­ple to sit less—in ad­di­tion to sim­ply ex­er­cis­ing more—seems to be the most ef­fec­tive mes­sage in get­ting peo­ple to change their be­hav­ior. So from a pub­lic health per­spec­tive, there’s a dif­fer­ence in the mes­sages that are trans­mit­ted.

There’s been a lot of con­tro­versy in what the “right” lev­els of ex­er­cise ac­tu­ally are. Just last week a study sug­gested that we should be get­ting quite a bit more than the oft-rec­om­mended 150 min­utes/week, if we re­ally want to re­duce our risk of dis­ease. The au­thors of this new ad­vi­sory don’t make new rec­om­men­da­tions about the time or type of ac­tiv­ity we should try to get in—they ar­rive at the sim­ple con­clu­sion, “Sit less, move more.” Which is vague, if ac­cu­rate (and fol­low­able) ad­vice.

Per­haps that’s all we need at the mo­ment. Since we don’t know ex­actly how much ex­er­cise we need (and it prob­a­bly de­pends on a slew of in­di­vid­ual fac­tors), and what ac­tiv­i­ties count as ex­er­cise, maybe just re­mind­ing our­selves to get up once in a while and move around a bit is enough for now.


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