Maintenance effects of a multilevel workplace intervention to reduce sedentary time: twenty-four-month follow-up of the group randomized clinical trial 'Stand and Move at Work'.

Background: The long-term impact of multilevel workplace sedentary behavior interventions has not been established beyond 12-months. We conducted a 2-arm group randomized trial examining the 24-month efficacy of a multilevel workplace intervention with sit-stand workstations (SSW) relative to the same multilevel intervention with delayed SSW implementation until 12-months.

Methods: Worksites (N = 24 worksites, N = 630 employees) were randomized to participate in Stand and Move at Work and received: (a) STAND + , a 12-month multilevel behavioral intervention targeting reductions in sedentary time and increases in light physical activity (LPA) with SSW delivery during the 12-months or (b) MOVE + , the same multilevel intervention, however with SSW delivery at the end of the 12-month primary assessment period. We present maintenance endpoints (24-month follow-up) of objectively measured sedentary behavior variables as well as cardiometabolic biomarkers of the total sample and an at-risk exploratory dysglycemic (prediabetes or diabetes) subgroup per study arm.

Results: All worksites (N = 24; from academic [n = 8], industry/healthcare [n = 8], and government [n = 8] sectors) were retained and participated in 24-month follow-up data collection. A total of 464 participants (248 STAND + , 216 MOVE + ; 19 ± 6 per worksite; 45.8 ± 10.6 years of age, 73% female) completed the 24-month assessment. At 24 months, the adjusted within-arm difference in sitting was -37.3 (CI:-51.9, -22.7) min per 8 h workday for STAND + and -23.4 (-39.7, -7.0) min per 8 h workday for MOVE + . Findings at 12-months were reproduced at 24-months, in which the majority of reductions in sitting translated to increasing standing with minimal change in LPA. There were no significant changes in cardiometabolic risk within the total sample, while there were some significant changes in triglycerides and blood pressure for the dysglycemic participants.

Conclusions: Multilevel workplace interventions incorporating SSWs have the potential to sustain reductions in workplace sedentary time through 24-months. Further, delayed introduction of SSWs following a 12-month multilevel workplace intervention seem to produce similar sitting time reductions relative to immediate introduction. SSWs are a robust environmental stimulus within multilevel interventions targeting workplace sedentary behavior. A larger sample size is needed to detect concomitant impact on cardiometabolic health.

Trial registration: ClinicalTrials.gov Identifier: NCT02566317. Registered on 2 October 2015, the first participant enrolled 11 January 2016. https://clinicaltrials.gov/ct2/show/NCT02566317 . See Consort checklist.