In an increasingly busy world, sedentary behaviour – that is sitting for prolonged periods of time – has become more common.

People often work long hours at their desk and wind down with time spent in front of the TV. Furthermore, commuting via car is common so people may transfer from the car, to the office, back to the car and then home to the couch in a day.

Lack of physical activity and increased time spent sedentary has been found to increase the risk of a number of chronic diseases and death.

It’s known that increasing levels of physical activity can improve health outcomes and reduce chronic disease. What’s less known, however, is whether or not increasing levels of physical activity can counteract the detrimental effects of large amounts of time spent sitting.

Researchers reviewed the evidence around the association between sedentary behaviour at work and physical activity levels and risk of all-cause death. Researchers gathered a number of studies that recorded physical activity levels, time spent sitting and all cause, as well as disease-specific death rates.

Sedentary behaviour was measured in daily sitting and TV-viewing time. Physical activity levels were assessed in the studies via self-reported questionnaires. Data were analysed for all cause death in addition to heart disease, breast, colon and colorectal cancer deaths. Researchers compared the data from those who had different amounts of sitting times and varying levels of physical activity.

The results showed that, in those people with the highest levels of physical activity, there was no significant association between time spent sitting and death. In this group, however, an association remained, albeit reduced a little, for high TV-viewing time.

For those with moderate levels of physical activity there was still an association between sitting time and premature death, however this was attenuated according to the level of physical activity undertaken compared with those in the least active group.

Implications

This review suggests that high levels of physical activity, about 60 – 75 minutes at moderate intensity per day, significantly reduced the risk of death associated with long periods of time spent sitting.

In those for whom this level of physical activity is unattainable, more moderate levels of physical activity attenuated the risk. These findings add further weight to the benefits of getting up and being active throughout the day.

Even incidental exercise can help so take the stairs instead of a lift; walk, cycle or catch public transport to work; and try to get up out of you chair at work throughout the day so that you do not spend the whole working day sedentary.

Last Reviewed: 06/12/2019

Norman Swan Medical Communications



References

Ekelund, U et al. (2016). Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. Lancet, 388, 1302-10.

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