Influencing sedentary time in the workplace: Understanding behaviour change through accumulation patterns, temporal variations and use of strategies

Abstract

Background:nSedentary behaviour is defined as any waking behaviour with low energynexpenditure (ln1.5 METs) while in a sitting, reclining or lying posture. There is now substantial evidence on adverse health outcomes associated with excessive sedentary time, especially time spent in prolonged sedentary bouts (e.g., l30 minutes duration). As total sedentary time is made up of multiple bouts of varying duration, it is important to understand how sedentary time is accumulated and how these patterns may change following intervention. Time and date-stamped activity monitors provide the opportunity to examine accumulation patterns (e.g., bout number, duration, postural transitions) and temporal variations (i.e., when sedentary time occurs).The desk-based workplace is a key setting for intervention with more than half of daily sedentary time accrued in the workplace, much of this in prolonged sedentary bouts. There is growing evidence examining workplace-delivered interventions, with multi- component interventions appearing to be most effective. To date, there has been limited reporting of how and when the changes in workplace sitting and activity occur, and whether behaviour change in the workplace impacts on behaviour outside of that setting. Furthermore, it is important to understand the underlying mechanisms influencing how the behaviour change is achieved, however, few studies have examined what strategies workers or workplaces use to reduce workplace sedentary time.Aim:nThe aim of this thesis was to examine, in the context of interventions to reduce sedentary time in the desk-based workplace,nhownandnwhennreductions in sedentary time occurred, andnwhatnstrategies workers use to achieve this change following intervention.Methods and Results:nThis thesis research utilises data from the Stand Up Australia research program.nStudy 1 (Chapter 4)nused data from the four-week Stand Up Comcare non-randomised intervention to examine how and when sedentary time changed during work hours. Sedentary accumulation patterns (bout number and duration) and temporal variations (hourly change) were examined using activPAL3 data. Exposure variation analysis was used to examine what sedentary time was replaced with. Both the number and duration of sitting bouts reduced following intervention, with sitting time primarily replaced with standing, with minimal changes in stepping. Reductions were evident across all work hours, varying by hour of the day (p=0.015).Studies 2 (Chapter 4) and 3 (Chapter 5)nused data from the 12-month Stand Up Victoria cluster-randomised controlled trial, which delivered a multi-component intervention comprising organisational, environmental (including sit-stand workstations) and individual strategies to reduce prolonged workplace sitting. InnStudy 2, sitting, prolonged sitting, standing and stepping outcomes (activPAL3) were assessed separately over five timeframes (work and non-work hours). Hourly change in sitting time (primary outcome) was examined during work hours, with compositional data analysis used to explore the relationships of changes during and outside of work. Relative to controls, intervention participants reduced sitting (including prolonged sitting), increased standing, and maintained stepping time during work hours on workdays. Reductions in sitting occurred at all work hours, but not equally. Changes during and outside of work on workdays were very weakly correlated in both the intervention group (r=-0.07) and controls (r=-0.09).Within Stand Up Victoria, intervention participants were guided by trained health coaches to identify individual-level strategies to address the key intervention targets (lStand Upr, lSit Lessr, lMove Morer). This data was used innStudy 3nto describe the strategies participants chose, with decision tree models used to examine how these strategies related to device- based (activPAL3) sitting and activity outcomes. Over 80 different strategies were nominated, with phone and task-based strategies common across intervention targets. The strongest predictors were nominating g3 h/day of workstation standing (to reduce total workplace sitting) and nominating at least one task-based strategy (to increase purposeful walking). Preliminary findings on strategy use in the BeUpstanding program, the translational arm of Stand Up Australia, demonstrated that walking to a colleague (rather than email) was the most commonly reported individual-level strategy at baseline, while allnwork teams chose lleaving the desk at lunch breaksr as a strategy to reduce sedentary time.Conclusions:nSedentary accumulation patterns can be changed with intervention. Workers successfully reduced both bout number and duration, with sedentary time primarily replaced with standing. Reductions occurred almost exclusively during work hours, the primary intervention setting, with changes at each hour of the work day. Workers chose a wide variety of strategies with the choice of strategy and number of strategies appearing relevant for behavioural change. Collectively, these findings contribute to key evidence gaps and provide exemplars of novel statistical approaches, which may be used to utilise activity monitor data to understand patterns of sedentary timenfollowing intervention. More research is needed across different types of interventions and work environments to further understand the impact of patterns of change and use of strategies following intervention. Future research should explore how to support behaviour change throughout the whole day in an optimal mix of sitting, standing and moving.