The Effects of UPcomplish on Office Workers' Sedentary Behaviour, Quality of Life and Psychosocial Determinants: A Stepped-Wedge Design.

BACKGROUND: Sedentary behaviour (SB) affects cardiometabolic health and quality of life (QoL). We examine the effects of UPcomplish, a 12-week data-driven intervention, on SB, QoL and psychosocial determinants among office workers. METHODS: Participants were recruited via judgement sampling. Five groups starting with time-lags of 7 weeks (n = 142, 96 females) received 14 feedback messages (FBMs) which were tailored to SB patterns, goals and hurdles. Participants received questionnaires at the beginning, middle and end of the intervention and wore an accelerometer measuring SB, operationalized as proportions (compositional data approach, CoDA) and summed squared sitting bouts (SSSB). We used linear mixed-effects models with random intercepts for weeks (between-subjects) and individuals (within-subjects). RESULTS: UPcomplish did not reduce SB. Within-subjects compared to baseline, FBM #3 (ßCoDA = 0.24, p < .001, 95% CI [0.15, 0.33]; ßSSSB = 20.83, p < .001, 95% CI [13.90, 27.28]) and #4 (ßCoDA = 0.20, p < .001, 95% CI [0.11, 0.29]; ßSSSB = 24.80, p < .001, 95% CI [15.84, 33.76]) increased SB. QoL was unaffected. Perceived susceptibility was lower after FBMs #6 to #8 (ßbetween = - 0.66, p = .04, 95% CI [- 1.03, - 0.30]; ßwithin = - 0.75, p = .02, 95% CI [- 1.18, - 0.32]). Within-subjects, intentions to sit less were higher after FBMs #1 to #5 (1.14, p = .02, 95% CI [0.61, 1.66]). Improvements in determinants and in SB were not associated, nor were improvements in SB and in QoL. CONCLUSIONS: Compared to VitaBit only, UPcomplish was not beneficial. Environmental restructuring might be superior, but detailed analyses of moderators of effectiveness are needed.