Objective Poor cardiorespiratory fitness and health is common among childcare workers. We designed the `Goldilocks-games` according to the Goldilocks Work principle to provide high-intensity physical activity for childcare workers. We investigated the effectiveness of this Goldilocks Work intervention in increasing occupational high-intensity physical activity and improving work-related health.

Methods In a two-arm cluster randomized trial, 16 childcare institutions with 142 workers were randomly allocated to either an 8-week Goldilocks Work intervention or a control group. The primary outcome was occupational time in high-intensity physical activity. Secondary outcomes were occupational time in active physical behaviors, heart rate during sleep, pain, physical exhaustion, energy at work, work productivity, and need for recovery.

Results The intervention was successfully delivered and received. Both groups had a low amount of occupational high-intensity physical activity at baseline, and the intervention group reported playing the games 3.1 [standard deviation (SD) 1.5] times/week for a duration of 112.2 (SD 175.0) min/week. However, the intervention did not increase high-intensity physical activity or the secondary outcomes, except for energy at work, measured on a scale from 0–10, increasing 0.65 [95% confidence interval (CI) 0.08–1.21], and need for recovery, measured on a scale from 1–5, decreasing -0.32 (95% CI, -0.54– -0.09).

Conclusion The intervention was successfully delivered and received, but did not increase high-intensity physical activity. The intervention group increased their energy at work and decreased their need for recovery, but not the other health-related outcomes. Further research on how to design and implement health-promoting work environment interventions in childcare is needed.

Key terms childcare worker; cluster-randomized controlled trial; Goldilocks Work intervention; high-intensity physical activity; physical activity; RCT; workplace intervention

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