Background
Sedentary behaviour (taken from the Latin term
sedere; to sit) has been operationally defined as any activity that involves an energy expenditure of ≤ 1.5 METS (metabolic equivalents), performed in seated or lying position [
1]. Emerging research evidence identifies sedentary behaviour as a risk factor for negative health outcomes in the adult population; this risk is distinct and independent from risk associated with physical inactivity [
2-
4]. A lack of breaks in sedentary time is also related to metabolic disease risk [
5,
6]. For example, lipoprotein lipase is regulated differently following sedentary behaviour and physical activity; whilst a reduction in LPL activity occurs only in oxidative muscle fibres following sedentary behaviour, physical activity promotes increased LPL activity in glycolytic muscle fibres [
7]. Further, a recent intervention study found that self-reported sitting time was significantly associated with a component of DNA; telomere length [
8] Shortening of telomeres is associated with ageing and onset of disease [
9]. This evolving evidence raises the question, “What should the person who sleeps an average of 8 hours per day [and is physically active for 30 minutes per day] do for the remaining 15.5 hours?” [
10]. Thus, research and policy guidelines, such as the UK’s ‘Start Active, Stay Active’ policy are now promoting both increases in physical activity and decreases in sedentary behaviour, stating adults should “
minimise the amount of time spent being sedentary (sitting) for extended periods” [
11].
Physical activity has been defined as “any bodily movement…that results in energy expenditure” [
12]. There is a well-established body of evidence supporting the health benefits of physical activity [
13]. However, physical activity is a complex behaviour; participation differs among different socio-economic groups and in the contexts and environments that contribute to health inequalities [
14-
16]. In the UK, it is estimated that over 73% of working age adults were engaged in full time or part time employment between April 2014 and June 2014 [
17] and that adults spend an average of 60% of the working day at the workplace [
18]. Thus, the workplace is an ideal setting for promoting physical activity and reductions in sitting. The office is a particularly important workplace setting, given the high proportion of sedentary time in desk-based office workers. For example, an observational study measured objectively the sedentary behaviour and physical activity of 50 office-based employees for 7 consecutive days; it found that, on average, 81.8% of working hours were spent engaged in sedentary behaviours, compared to 68.9% of non-work hours. Additionally, there were fewer breaks in sedentary time, and less light-intensity activity, during working hours than during non-working hours (p < 0.001) [
19]. This suggests that office-workers are more sedentary and less active during work than outside work and thus the office-based workplace is a crucial context for intervention to promote increases in physical activity and reductions in prolonged sitting. In desk-based office occupations, prolonged sitting is likely to occur in the context of travelling to work and participating in meetings, however, approximately two-thirds of workplace sitting time is spent at a desk [
20].
One response to reducing sitting time in the workplace is the installation of sit-stand workstations. Sit-stand workstations offer height-adjustable desk equipment for computer screens and keyboards allowing employees a choice of desk-based working positions. Several studies have examined the contribution of sit-stand workstations to a range of sedentary behaviour, health and productivity outcomes. Previous sit-stand workstation intervention studies have seen varying reductions in the amount of time spent sitting, ranging from 66 minutes to 143 minutes per day [
21]. A recent meta-analysis of activity-permissive workstations revealed that the reduction in sedentary behaviour is greater in interventions that incorporate a change to the working environment (i.e. an activity-permissive workstation), than interventions that do not [
22]. Physiological research shows that using a sit-stand workstation for 185 minutes, immediately after eating, can reduce post-prandial glucose excursion by 43% [
23]. A recent review of empirical studies examining the relationship between sit-stand workstations and a range of measures of productivity revealed that whilst the majority of studies show that using a sit-stand workstation had no influence on productivity, no studies showed a reduction in productivity [
24]. In line with an ecological approach to behaviour change [
25], initial research has shown that greater reductions in sitting time (56 min/8-hour workday) can be achieved as a result of a multi-component sit-stand workstation intervention (incorporating individual and organisational level components) compared to receiving a sit-stand workstation alone [
26]. However, this needs to be replicated over a prolonged time-period (e.g. 12 months), on outcomes related to physical activity (distinct from sitting, standing and stepping). Whilst the feasibility of using sit-stand workstations has been qualitatively explored with desk-based office workers [
27], outcome-focused studies dominate this research area. Understanding of the social processes that encourage and restrict standing and physical activity in the workplace is required. The absence of systematic and rigorous process evaluations of sit-stand workstation interventions will impede the wider adoption of sit-stand workstations across organisations [
28,
29].
Aims
The primary aim is to determine the effect of a 12 month multi-component sit-stand workstation intervention, incorporating organisational, environmental and individual level strategies, on physical activity within the workplace (primary outcome). Secondary aims are to: determine the effect of the sit-stand workstation intervention on physical activity outside of the workplace (secondary outcome), and to determine whether the multi-component intervention is more effective than the sit-stand workstation provision alone. The process evaluation will examine the factors that influence sitting, standing and active behaviours in the workplace.
Discussion
Given the accumulating evidence of the health risks of prolonged sitting [
2-
8], and the epidemiological evidence that illustrates the high occurrence of prolonged sitting in office-based workplaces [
18-
20], high quality intervention studies are necessary to provide an evidence-base of ‘what works’ to reduce prolonged sitting and increase activity in the workplace. It is not only necessary to understand
whether an intervention is effective, but also to understand
why an intervention is, or is not, feasible, effective or sustainable. Accordingly, the contiguous systematic and rigorous process evaluation integral to this study represents an innovation within this area of research. Eliciting understanding of the social processes that underpin use of sit-stand workstations and physical activity within the workplace is crucial for understanding how to influence behaviour. A strength of the present study is that it will create a comprehensive picture of total physical activity using two objective measures; these will capture sitting, standing, and light, moderate and vigorous physical activity, alongside an activity diary, that will provide contextual information. The latter will include the type and purpose of the activities and the inactive behaviours undertaken. An understanding of the influence of the sit-stand workstation intervention on physical activity during non-work hours will also be permissible, as physical activity will be measured over the course of the entire day. A further strength is the long-term nature of the evaluation, which permits assessment of the sustainability of sit-stand workstation approaches for reducing prolonged sitting and increasing physical activity in the workplace [
35]. The findings of this pilot study will provide evidence to guide future research, as well as the development of guidelines and policy to optimise the promotion of workplace health and wellbeing.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
JH conceived of the study, participated in the design of the study and drafted the manuscript. LM participated in the design of the study and helped draft the manuscript. TK participated in the design of the study and critically revised the manuscript. AM participated in the design of the study and critically revised the manuscript. All authors read and approved the final manuscript.
JH is a PhD researcher in physical activity and health. LM is Deputy Director of the Brunel Centre for Health and Wellbeing and Senior Lecturer in Sport, Health and Social Science. TK is Theme Leader, Social Science and Health and Professor of Sport and Social Science.AM is Professor of Applied Physiology.