How do you define “sedentary behaviour”?

In science, having clear and specific definitions for terms is essential. But for rapidly developing fields such as sedentary research, confusion can quickly arise over new terminology. A new publication in the International Journal of Behavioural Nutrition and Physical Activity reports the final definition of key terms related to sedentary behaviour. Here to tell us more is author of the paper, Travis Saunders.

Figure 1. Conceptual framework from Tremblay et al. 2017.

In the past 20 years, the amount of research published using the term sedentary behaviour has grown exponentially. In 1997, there were 61 papers published on Pubmed using the term sedentary behaviour. Last year there were 1,021. There were 474 in just the first 5 months of 2017.

Figure 2. Number of research papers published on Pubmed using the term “sedentary behaviour” between 1997 and 2017.

As with any new field, this has led to a lot of confusion when it comes to terminology.  Many people still use the term “sedentary” to refer to participants that others would describe as “inactive”. This might seem like meaningless hair splitting, but it really does matter. If I am looking for research on “sedentary behaviour” but you call it “inactivity”, my searches will never pull up your article. Or if I do see your article, I might assume it’s on a different topic and ignore it. Having a common set of terms can go a long way in communicating research on a given topic.

In 2012 the Sedentary Behaviour Research Network (SBRN) published a letter to the editor suggesting a consensus definition for sedentary behaviour. The letter was signed by 52 researchers from around the world, and has become the most widely cited definition of sedentary behaviour.

However, the field of sedentary behaviour research has continued to evolve since 2012, and several authors have recently called for further clarification around the term sedentary behaviour, as well as related terms, such as screen time, sedentary behaviour pattern, and breaks in sedentary time.  Further, it has been pointed out that the original definition was ill-suited for certain populations, including very young children, and those with mobility impairment.

Building on their previous work, SBRN recently embarked on a process to develop consensus around key terms related to sedentary behaviour, and to ensure that these terms are applicable for all age groups and physical abilities. A call was put out to all SBRN members, and 87 responded with interest. A steering committee created draft definitions for 10 key terms, which then went through several rounds of comments and feedback from all 87 authors.

The final definitions (listed below) are available in a publication in the International Journal of Behavioural Nutrition and Physical Activity (which also includes full details on the iterative process used to derive the definitions) and via www.sedentarybehaviour.org. The definitions were also presented at the International Society for Behavioural Nutrition and Physical Activity conference in Victoria, Canada, on June 10, 2017.

We hope that these definitions will be widely supported and adopted, and advance future research, interventions, policies, and practices related to sedentary behaviour.

Term Definition
1.       Physical Inactivity An insufficient physical activity level to meet present physical activity guidelines.
2.       Stationary Behavior Stationary behavior refers to any waking behaviour done while lying, reclining, sitting, or standing, with no ambulation, irrespective of energy expenditure.
3.       Sedentary Behaviour Sedentary behavior refers to any waking behavior characterized by an energy expenditure ≤1.5 METs, while in a sitting, reclining or lying posture.
4.       Standing A position in which one has or is maintaining an upright posture while supported by one’s feet.
5.       Screen Time Screen time refers to the time spent on screen-related behaviors.  These behaviors can be performed while being sedentary or physically active.
6.       Non-Screen-Based Sedentary Time Non-screen-based sedentary time refers to the time spent in sedentary behaviors that do not involve the use of screens.
7.       Sitting A position in which one’s weight is supported by one’s buttocks rather than one’s feet, and in which one’s back is upright.
8.       Reclining Reclining is a body position between sitting and lying.
9.       Lying Lying refers to being in a horizontal position on a supporting surface.
10.   Sedentary Behavior Pattern The manner in which sedentary behavior is accumulated throughout the day or week while awake (e.g. the timing, duration and frequency of sedentary bouts and breaks)

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