Too much sitting can be deadly—even if you exercise, review finds

January 20, 2015 by Maureen Salamon, Healthday Reporter
Too much sitting can be deadly -- even if you exercise, review finds
Researcher suggests ways to include movement in your day that goes beyond that hour at the gym.

Regular exercise doesn't erase the higher risk of serious illness or premature death that comes from sitting too much each day, a new review reveals.

Combing through 47 prior studies, Canadian researchers found that prolonged daily sitting was linked to significantly higher odds of heart disease, diabetes, cancer and dying.

And even if study participants exercised regularly, the accumulated evidence still showed worse health outcomes for those who sat for long periods, the researchers said. However, those who did little or no faced even higher health risks.

"We found the association relatively consistent across all diseases. A pretty strong case can be made that and sitting is probably linked with these diseases," said study author Aviroop Biswas, a Ph.D. candidate at Toronto Rehabilitation Institute-University Health Network.

"When we're standing, certain muscles in our body are working very hard to keep us upright," added Biswas, offering one theory about why sitting is detrimental. "Once we sit for a long time . . . our metabolism is not as functional, and the inactivity is associated with a lot of negative effects."

The research is published Jan. 19 in the online issue of Annals of Internal Medicine.

About 3.2 million people die each year because they are not active enough, according to the World Health Organization, making physical inactivity the fourth leading risk factor for mortality worldwide.

Among the studies reviewed by Biswas and his team, the definition of prolonged sitting ranged from eight hours a day to 12 hours or more. Sitting, or ubiquitous with sitting such as driving, using the computer or watching TV, shouldn't comprise more than four to five hours of a person's day, Biswas said, citing guidelines issued by Public Health Agency of Canada.

"We found that exercise is very good, but it's what we do across our day," he said. "Exercise is just one hour in our day, if we're diligent; we need to do something when we're not otherwise exercising, like finding excuses to move around, take the stairs, or carry groceries rather than use the [shopping cart] at the supermarket."

The biggest health hazard stemming from prolonged sitting, according to the review, was a 90 percent higher risk of developing type 2 diabetes. Among studies examining cancer incidence and deaths, significant links were specifically noted between sedentary behavior and breast, colon, uterine and ovarian cancers.

One study in the review showed that fewer than eight hours of sitting time per day was associated with a 14 percent lower risk of potentially preventable hospitalization.

Dr. Joshua Septimus, a clinical associate professor of internal medicine at Houston Methodist Hospital in Texas, praised the new research, saying it "gives us more data to help counsel our patients."

"The idea that we could exercise for 15 or 20 minutes a day and that could completely erase any harms of a sedentary lifestyle for the other 23 hours a day is just too hopeful," Septimus noted. "This showed us that yes, there is some benefit to physical activity . . . but it's not enough."

Biswas and his colleagues offered additional tips to reduce sedentary time, including:

  • Taking a one- to three-minute break every half-hour during the day to stand (which burns twice as many calories as sitting) or walk around,
  • Standing or exercising while watching TV,
  • Gradually reducing daily time by 15 to 20 minutes per day, aiming for two to three fewer sedentary hours over a 12-hour day.

Explore further: Sitting around in middle age doesn't bode well for old age

More information: Aviroop Biswas, et al. Sedentary Time and Its Association With Risk for Disease Incidence, Mortality, and Hospitalization in Adults: A Systematic Review and Meta-analysis. Annals of Internal Medicine, 2015 DOI: 10.7326/M14-1651

The World Health Organization offers a fact sheet about physical inactivity.

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4 comments

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Skepticus
3 / 5 (4) Jan 20, 2015
Oversimplification. Sitting a lot alone is not deadly. Eating a lot and inactivity is. Budhhist monks sit for hours in meditation and almost all of them lived into their 80s and 90s, without diabetes, heart disease, etc. Why? Calories restriction, due to their meager meals, in some sects only one meal per 24 hrs.
alfie_null
3 / 5 (2) Jan 20, 2015
Regurgitating 47 studies done by others, for other purposes, they find some correlation between a couple factors. Then are eager to offer glib advice to the rest of us on how to avoid becoming a statistic.

Few question that being active is better than being sedentary. That makes it a smart choice on which to do a paper. What are the boundaries between active and sedentary? I don't feel assured these guys know.
katesisco
not rated yet Jan 20, 2015
Agree with Skepticus as sitting is the only choice except for reclining like the Romans. It is sitting in a stiff chair without body support that is bad, aka work. Putting your legs up is resting your heart similar to lying down.
dedereu
not rated yet Jan 23, 2015
I must stop sitting too much for reading medicalxpress.com

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