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A collage of people being sedentary including playing video games, driving, watching television and reading a book.

Exploring sedentary behaviour

In the last step, we discussed the intensity of activities in METS. Sedentary behaviour can also be expressed in terms of METS.

Sedentary behaviour is defined as “any waking activity characterized by an energy expenditure ≤ 1.5 metabolic equivalents and a sitting or reclining posture”. (Sedentary Behaviour Research Network, 2012).

Like physical activity, sedentary behaviour can be categorised in terms of occupational activities, domestic, leisure time and transport. Common sedentary behaviours include watching television, reading, using a computer and driving. Sedentary behaviour may seem like the opposite of physical activity, but it is an independent risk factor for certain chronic diseases and is therefore considered separately to physical activity, body weight, and diet.

  • For example, it is possible to be both physically active and sedentary. If you achieve 150 minutes of moderate to vigorous physical activity a week, but you also spend prolonged periods of time being sedentary every day, you can be considered both physically active and sedentary.

Research in the area of sedentary behaviour has been conducted in both adults and children, and clearly links sedentary behaviour with chronic disease, morbidity and mortality in adults (Tremblay et al, 2010; Proper et al, 2011; Grontved and Hu, 2011; Chinapaw et al, 2011; Thorp et al, 2011; Boyle et al, 2011). It is harder to determine the effects of sedentary behaviour on health in childhood since the relevant diseases generally do not surface until later in life; however, available evidence suggests that sedentary behaviour may also be a health risk in children and young people (Thorp et al, 2011).

It is especially important to discourage prolonged sedentary behaviour in children, since we know that sedentary behaviour increases with age, and a sedentary child is likely to become a sedentary adult (Biddle et al, 2010).

There is international consensus that people of all ages “should minimise the amount of time spent being sedentary (sitting) for extended periods” (Department of Health, 2011). However unlike physical activity, few organisations have given specific recommendations, for example, by stating that sedentary periods of greater than two hours should be interrupted. We will be exploring these recommendations in greater detail in Step 1.16.

Graphic showing relationship between activity intensity and sedentary behaviour

Tips for reducing sedentary behaviour

  • If you have a desk job, set an alarm to remind yourself to get up every hour. Simply walking to a water fountain or the photocopier can help.
  • Target the whole family (including parents, brothers and sisters) when trying to reduce sedentary behaviour among children or adolescents.
  • Ensure a reduction in one sedentary activity is not simply replaced by another (e.g. half an hour of television viewing is cut but replaced by computer use).
  • Encourage active transport to school/work.

In the comments section below, consider the following questions:

  • Do you think there should be specific recommendations about the amount of sedentary time children should engage in?

  • What barriers might stand in the way of children reducing their sedentary behaviour to periods of less than two consecutive hours?

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This article is from the free online course:

Exercise Prescription for the Prevention and Treatment of Disease

Trinity College Dublin