The effectiveness of multi-component interventions targeting physical activity or sedentary behaviour amongst office workers: a three-arm cluster randomised controlled trial

BackgroundInterventions to increase physical activity or reduce sedentary behaviour within the workplace setting have shown mixed effects. This cluster randomised controlled trial assessed whether multi-component interventions, focusing on changes at the individual, environmental, and organisational levels, either increased physical activity or reduced sedentary behaviour, compared to a passive control group.MethodsTeams of office-workers from two companies participated in one of two interventions (iPA: targeting physical activity; or iSED: targeting sedentary behaviour), or wait-list control group (C). Exclusion criterion was very high physical activity level (MVPA >= 30min/day in >= 10min bouts every day). Randomisation occurred at the level of workplace cluster, and groups were randomly allocated (1:1) with stratification for company and cluster size. Personnel involved in data collection and processing were blinded to group allocation. Both interventions included five sessions of cognitive behavioural therapy counselling for 6months. iPA included counselling focused on physical activity, access to a gym, and encouragement to exercise, and go for lunch walks. iSED included counselling on sedentary behaviour and encouragement to reduce sitting and increase engagement in standing- and walking-meetings. At baseline and the 6-month mark accelerometers were worn on the hip and thigh for 7days. The primary outcomes were group differences in time spent in moderate-to-vigorous intensity physical activity (%MVPA) and in sedentary behaviour (%), analysed using Bayesian multilevel modelling for those with complete data.ResultsTwo-hundred and sixty three office workers (73% women, mean age 429years, education 152years) were randomised into 23 cluster teams (iPA n=84, 8 clusters; iSED n=87, 7 clusters; C n=92, 7 clusters). No significant group differences (posterior mean ratios: 95% credible interval) were found after the intervention for %MVPA or for %Sedentary. %MVPA: iPA vs C (0.04: -0.80-0.82); iSED vs C (0.47: -0.41-1.32); iPA vs iSED (0.43: -0.42-1.27). %Sedentary: iPA vs C (1.16: -1.66-4.02); iSED vs C (-0.44: -3.50-2.64); iPA vs iSED (-1.60: -4.72-1.47).Conclusions The multi-component interventions focusing on either physical activity or sedentary behaviour were unsuccessful at increasing device-measured physical activity or reducing sedentary behaviour compared to a control group.Trial registration ISRCTN, ISRCTN92968402. Registered 27/2/2018, recruitment started 15/03/2018,