Research into sedentary behaviour (SB) in adults is growing rapidly, both in volume and sophistication . SB is defined as waking activity characterised by an energy expenditure ≤ 1.5 metabolic equivalents and a sitting or reclining posture. A recent overview of systematic reviews concluded that there is strong evidence for a positive relationship between SB and all-cause mortality, fatal and non-fatal
cardiovascular disease, type 2 diabetes mellitus and metabolic syndrome; along with moderate evidence for increased incidence rates of ovarian, colon and endometrial cancers. In addition, research suggests that SB may be a distinct risk factor, independent of physical activity, for multiple adverse health outcomes . It is estimated that reductions of 1–2 hours of sedentary time per day could equate to substantial reductions in cardiovascular disease risk. A Cochrane Review on workplace interventions to reduce sitting at work recently concluded that there is very low quality evidence that sit-stand desks can reduce sitting time at work, and that the effects of policy changes and information and counselling are inconsistent. However workplace sitting only represents one domain of SB. For example TV viewing is the chief contributor to SB in the United States with the average adult watching 5 hours of TV per day. In addition, inactive travel modes and other non-occupational behaviours such as leisure-time computer use are increasing. Only two systematic reviews of interventions to reduce sedentary time in adults have been published. However these reviews include interventions that are designed to increase physical activity but also report changes in sedentary time, rather than solely focusing on interventions that purposely aim to reduce SB. Eighteen out the 51 included studies in Martin et al (2015) and 22 of the 63 studies included in Prince et al (2013) incorporated a component that specifically targeted SB. In the reviews to date SB interventions in non-occupational settings were reported together with workplace settings. Additionally, the review by Prince and colleagues did not report health outcomes, thought to be the key benefit of reduced SB, although these outcomes are available for several of the included studies in non-workplace settings. This rapidly growing field will inform the development of public health policy over the coming decade and a regularly updated, robust, comprehensive review of the evidence is required to support this task. The author team estimate that approximately 18 interventions specifically targeting SB in adults in non-occupational
settings have been published. With several more articles describing study protocols recently made available we suggest that this number is likely to increase in the coming 18 months.
Objectives
To evaluate the effectiveness of interventions for reducing sedentary behaviour on sedentary time
To evaluate the impacts of such interventions on measures of health status (including adverse events & unintended outcomes)
To determine whether specific components of interventions are associated with changes in sedentary behaviour
To examine if there are any differential effects of interventions by health inequalities (e.g. age, gender, income, employment)
