7. Project Summary / Abstract. Prolonged sitting and inadequate moderate to vigorous intensity physical activity (MVPA) are pervasive risk factors for cardiovascular disease (CVD).1–6 CVD is the leading cause of death globally, prematurely taking 655,000 American lives annually.7 Recent research has shown that some benefits of moderate to vigorous physical activity can be accrued in motivationally accessible, short, 2-5 minute bouts throughout the day rather than needing to be a single, longer, continuous bout.8–13 Identifying an effective intervention to interrupt prolonged sitting throughout the day with short, 2-5 minute bouts of MVPA, “exercise snacks,” can provide an accessible way for adults with sedentary jobs to change two CVD risk factors. The current R34 proposes to user-test and pilot the acceptability, feasibility, and clinical signal detection of a novel intervention, MOV’D, to interrupt prolonged sitting with short bouts of MVPA, compared with a Fitbit-only control. Preliminary evidence from an NHLBI K01-funded proof-of-concept study found that evidence-based behavior change technique (BCT) texts to a private, social-media based support group increased steps throughout the day compared to a Fitbit-only control group, but the effects did not last. MOV’D significantly adds to this initial work by: adding videos teaching exercise snacks and BCTs to increase initial and maintained change; adding a peer-coach feature to increase engagement; targeting exercise snacks instead of single exercise bouts; and targeting an at-risk, understudied population (receptionists and clerical health care staff with CVD risk factors). Our team partnered with upper management of Stanford clerical health care staff (low wage positions with high job constraints on physical activity). Together, we have occupationally-tailored the MOV’D program. Before conducting a fully-powered efficacy trial (ORBIT Phase III), we need to user-test and refine two intervention components with our target population (ORBIT Phase Ib; Aim 1); and conduct the necessary acceptability, feasibility, and clinical signal detection pilot trial (ORBIT Phase IIb; Aim 2), which will obtain recruitment and retention parameters to inform the Phase III trial. The Aim 1 user-testing of both the exercise snack and BCT videos will be done with participants from the target population to ensure learning effectiveness, appropriateness, and acceptability. The Aim 2 pilot will randomly assign n=60 participants from the target population to either MOV’D or a Fitbit-only control for 6-weeks, with a 6-month follow-up. We will compare immediate and 6-month data to a priori benchmarks for acceptability, feasibility, and clinical signal detection in workday prolonged sitting bout length and workday MVPA minutes. Results from the proposed R34 will directly inform the R01 for the Phase III trial of MOV’D to test efficacy and duration of effects. The long-term objective is to have a scalable, widely-accessible...