Sedentary behaviour has been linked to a number of diseases, including cancer.
Over the past century, technology has led to the automation of most of our transport, occupational and household tasks. In short, we sit a lot more than we used to. This change in lifestyle has resulted in dramatic reductions in total daily energy expenditure, which according to researchers is adversely associated with health outcomes including diseases such as diabetes, heart disease, and even cancer.
According to Peter Katzmarzyk, epidemiology professor at Pennington Biomedical Research Centre, sitting just three hours a day may increase your risk of type 2 diabetes and cardiovascular disease, potentially shaving two years from your lifespan. Katzmarzyk and his team sifted through data from five relevant studies of near 167,000 adults to reach their unsettling conclusion.
“The results of the epidemiological studies show that sitting seems to be an independent risk factor — in other words, it doesn’t matter if you a smoker or non-smoker, normal weight or obese, young or old, active or inactive — the results hold up for all sorts of people,” says Katzmarzyk.
In a separate review, researchers at the Baker IDI Heart and Diabetes Institute have linked sedentary behaviour to an increased susceptibility to cancer. What’s more disturbing is that the effect of sedentary behaviour on life expectancy is divorced from the amount of physical activity a person gets. It’s not just that you’re not exercising — it’s the sitting itself that is the problem.
“Evidence from observational and experimental studies suggests that prolonged sitting is associated with increased adiposity, alterations in glucose regulation and insulin sensitivity, and chronic, low-level inflammation,” says Brigid Lynch, a National Health and Medical Research Council (NHMRC) Postdoctoral Fellow.
According to Lynch, studies to date have found an association between sedentary behaviour and colorectal, ovarian and endometrial cancers. An association has also been shown for non-Hodgkin lymphoma in women, but not in men.
“A number of biological pathways relating prolonged sitting to the development and progression of cancer have been proposed, although at this point in time these mechanisms are not well understood,” Lynch explains. For instance, “adiposity may facilitate carcinogenesis directly, or through a number of pathways including increased levels of sex and metabolic hormones, chronic inflammation and altered secretion of adipokines.”
Both researchers suggest that everyone should try to become more active in their daily lives through a combination of spending less time sitting and more time on their feet, even if it means walking to talk to a colleague rather than sending them an email. Some suggestions for reducing daily sitting time are provided by the National Heart Foundation of Australia.