Background The ‘scale-up’ of effective physical activity interventions is required if they are to yield improvements in population health. The purpose of this study was to systematically review the effectiveness of community-based physical activity interventions that have been scaled-up. We also sought to explore differences in the effect size of these interventions compared with prior evaluations of their efficacy in more controlled contexts, and describe adaptations that were made to interventions as part of the scale-up process. Methods We performed a search of empirical research using six electronic databases, hand searched reference lists and contacted field experts. An intervention was considered ‘scaled-up’ if it had been intentionally delivered on a larger scale (to a greater number of participants, new populations, and/or by means of different delivery systems) than a preceding randomised control trial (‘pre-scale’) in which a significant intervention effect (p < 0.05) was reported on any measure of physical activity. Effect size differences between pre-scale and scaled up interventions were quantified ([the effect size reported in the scaled-up study / the effect size reported in the pre-scale-up efficacy trial] × 100) to explore any scale-up ‘penalties’ in intervention effects. Results We identified 10 eligible studies. Six scaled-up interventions appeared to achieve significant improvement on at least one measure of physical activity. Six studies included measures of physical activity that were common between pre-scale and scaled-up trials enabling the calculation of an effect size difference (and potential scale-up penalty). Differences in effect size ranged from 132 to 25% (median = 58.8%), suggesting that most scaled-up interventions typically achieve less than 60% of their pre-scale effect size. A variety of adaptations were made for scale-up – the most common being mode of delivery. Conclusion The majority of interventions remained effective when delivered at-scale however their effects were markedly lower than reported in pre-scale trials. Adaptations of interventions were common and may have impacted on the effectiveness of interventions delivered at scale. These outcomes provide valuable insight for researchers and public health practitioners interested in the design and scale-up of physical activity interventions, and contribute to the growing evidence base for delivering health promotion interventions at-scale. Trial registration PROSPERO CRD42020144842.

As a strategy for early childhood obesity prevention, a variety of dietary behavior and physical activity policies and guidelines published by leading health agencies and early childhood education and care (ECEC) licensing and accreditation bodies exist. Given the potential diversity in recommendations from these policies, this narrative review sought to synthesize, appraise and describe the various policies and guidelines made by organizational and professional bodies to highlight consistent recommendations and identify opportunities to strengthen such policies. An electronic bibliographic search of seven online databases and grey literature sources was undertaken. Records were included if they were policies or guidelines with specific recommendations addressing dietary behavior and/or physical activity practice implementation within the ECEC setting; included children aged >12 months and <6 years and were developed for high income countries. Recommended dietary behavior and physical activity policies and practices were synthesized into broad themes using the Analysis Grid for Environments Linked to Obesity framework, and the quality of included guidelines appraised. Our search identified 38 eligible publications mostly from the US and Australia. Identified guidelines were largely consistent in their recommendation and frequently addressed the physical and sociocultural environment and were well-aligned with research evidence. Broader consideration of policy and economic environments may be needed to increase the impact of such policies and guidelines within the ECEC setting.

Context Public health nutrition interventions shown to be effective under optimal research conditions need to be scaled up and implemented in real-world settings. Objectives The primary aim for this review was to assess the effectiveness of scaled-up public health nutrition interventions with proven efficacy, as examined in a randomized controlled trial. Secondary objectives were to: 1) determine if the effect size of scaled-up interventions were comparable to the prescale effect, and; 2) identify any adaptations made during the scale-up process. Data sources Six electronic databases were searched and field experts contacted. Study selection An intervention was considered scaled up if it was delivered on a larger scale than a preceding randomized controlled trial (“prescale”) in which a significant intervention effect (P ≤ 0.05) was reported on a measure of nutrition. Data extraction Two reviewers independently performed screening and data extraction. Effect size differences between prescale and scaled-up interventions were quantified. Adaptations to scale-up studies were coded according to the Adaptome model. Results Ten scaled-up nutrition interventions were identified. The effect size difference between prescale trials and scaled-up studies ranged from –32.2% to 222% (median, 50%). All studies made adaptations between prescale to scaled-up interventions. Conclusion The effects of nutrition interventions implemented at scale typically were half that achieved in prior efficacy trials. Identifying effective scale-up strategies and methods to support retainment of the original prescale effect size is urgently needed to inform public health policy. Systematic Review Registration PROSPERO registration no.CRD42020149267.