"It depends on the boss" - a qualitative study of multi-level interventions aiming at office workers' movement behaviour and mental health.

Purpose: This embedded qualitative study explored the acceptability, feasibility, and fidelity of two multi-level RCT interventions among office workers, aiming at improving movement behaviour to enhance mental health and cognition. The interventions addressed the organizational, environmental, and individual level.

Methods: Semi-structured interviews and focus group discussions were conducted with 38 stakeholders after completion of the interventions. Data were analysed using reflexive thematic analysis.

Results: The interventions were well appreciated, and office workers attributed improvements in movement behaviour and wellbeing to the interventions. Especially the cognitive behavioural therapy (CBT) based counselling and free gym access were appreciated, feasible and delivered as planned. Participants described existing workplace norms as barriers to more activity, particularly for reducing sitting. Support from managers and team support were considered crucial components. However, delivering these components was difficult.

Conclusions: The findings support the design of the multi-level interventions for changing movement behaviour. Results highlight the potential of CBT for this target group and the importance of manager and team support. Desired effects of similar multi-level interventions, including CBT, might be achieved in future studies that carefully address the issues with feasibility and acceptability and the resulting low fidelity of some intervention components that were identified in this study.