Effectiveness of the SMART Work & Life intervention for reducing sitting time and improving health in office workers
Office workers spend 70-85% of their time at work sitting and accumulate a large proportion (40-50%) of this time in prolonged bouts. Office workers also typically spend a large proportion of their leisure time sitting compared to other occupations. High levels of sitting have been linked to poor physiological and psychological health. In the workplace, lower levels of sitting have been linked to higher work vigour, higher job performance and lower presenteeism. Workplaces are therefore an ideal setting for implementing interventions to reduce daily sitting.
This work was funded by National Institute for Health Research (NIHR) to conduct the largest study of its kind worldwide to assess the effectiveness of an intervention on reducing sitting time and improving health, wellbeing, and work-related health and performance.
Objectives: Primary: To evaluate the impact of SMART Work & Life (SWAL), when delivered with and without a height-adjustable workstation, on daily sitting time compared to usual practice at 12 months. Secondary: To determine relative effectiveness and short (3 months) and longer (12 months) term intervention effects on other sitting and physical activity outcomes, and physical, psychological and health and work performance outcomes.
Design: Cluster three-arm randomised controlled trial with follow up at 3 and 12 months.
Setting: Local government councils in Leicester, Leicestershire, Greater Manchester and Liverpool, UK.
Participants: 78 clusters with 756 desk-based workers (mean age 44.7 years; 72.4% female; 69.7% white British).
Interventions: SWAL is designed to reduce sitting time inside and outside of work. It includes organisational, environmental, group and individual level behaviour change strategies, delivered by trained workplace champions (council employees). Clusters were randomised to one of three conditions: 1) the SWAL intervention (SWAL only); 2) the SWAL intervention with the provision of a height-adjustable workstation (SWAL plus desk); 3) control group, usual practice.
Main outcomes measures: Primary: Daily sitting time (thigh-worn accelerometer). Secondary: accelerometer-measured sitting time, prolonged sitting, standing time, and physical activity, self-reported lifestyle behaviours, musculoskeletal issues, markers of cardiometabolic health, work-related health and performance, fatigue, and psychological measures. Analyses used multilevel models, accounting for clustering.
Results: Daily sitting time at 12 months was significantly reduced in the intervention groups (SWAL only: -22.2 minutes/day (95% CI -38.8 to -5.7, p=0.003); SWAL plus desk: -63.7 minutes/day (-80.1 to -47.4, p<0.001)) compared to the control group. SWAL plus desk was more effective in changing sitting time than SWAL only (-41.7 minutes per day (95% CI -56.3 to -27.0, p<0.001)). Favourable differences in sitting and prolonged sitting for both intervention groups and for standing for the SWAL plus desk group were observed during work hours and work days only. There were small improvements in stress, wellbeing, vigour (work engagement sub-scale) and lower back issues for both intervention groups as well as output demands, social norms and support for SWAL plus desk group. Changes in all other secondary outcomes were small and non-significant.
Conclusions: SWAL only and SWAL plus desk groups sat less compared to the control group in the short and longer term, SWAL plus desk was more effective than SWAL only. Reductions in sitting time were largely replaced by standing time and changes occurred during work hours. Behaviour change was maintained between 3 and 12 month follow up. Small positive differences in stress, wellbeing, vigour and lower back issues were observed.