Too much sitting increases the risk of heart disease, type 2 diabetes, and cancer, regardless of how much a person exercises, according to new research.
The study, a systematic literature review published in Annals of Internal Medicine, aims to answer some of the questions regarding the relationship between prolonged sitting and health issues after adjusting for physical activity. Previous studies have failed to determine the exact nature of the relationship.
Researchers examined 47 studies, and found that, amongst people who sit for prolonged periods of time, even those who exercised regularly experienced worse health outcomes than people who didn’t spend a lot of time sitting down.
One of the studies reviewed indicates that people who spend less than eight hours sitting per day lowered their risk of hospitalisation by 14 per cent.
The World Health Organisation (WHO) suggests that 3.2 million people die every year as a result of inactivity.
The biggest sitting-related health risk revealed by the review was a 90 per cent increase in the risk of developing type 2 diabetes. Important links were also observed between inactivity and several types of cancer, including colon, uterine, breast, and ovarian.
Aviroop Biswas, of the Toronto Rehabilitation Institute-University Health Network, said: “We found the association relatively consistent across all diseases. A pretty strong case can be made that sedentary behaviour and sitting is probably linked with these diseases.
“When we’re standing, certain muscles in our body are working very hard to keep us upright. Once we sit for a long time … our metabolism is not as functional, and the inactivity is associated with a lot of negative effects.
“We found that exercise is very good, but it’s what we do across our day,” he explained. “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 trolley] at the supermarket.”
Dr. Joshua Septimus, a clinical associate professor of internal medicine at Houston Methodist Hospital in Texas, was full of praise for the new research, noting that it “gives us more data to help counsel our patients.”
“The idea that we could exercise for 15 to 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. This showed us that yes, there is some benefit to physical activity … but it’s not enough.”

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