Development of the FitBack online platform: Enhancing global child fitness assessment, health-related interpretation, and surveillance

• We detail the development of a free-for-use, multilingual, online platform tool which is accessible to children, parents, teachers, and healthcare professionals, designed to provide children with specific, evidence-based, interactive fitness testing feedback reports. • To do this, we first created a set of the most current, robust, and evidence-based health-related fitness cut-off points for each of the five most well-established fitness tests for clinical and research purposes. • The FitBack platform also provides valuable health information for policy makers, in their native language, to encourage and facilitate any interested persons to establish their own child fitness monitoring system(s). • The entire online platform, and harmonised surveillance monitoring system process, is fully supported by the online portal itself, where members have access to free infographics, multi-lingual online resources, an interactive European fitness map, examples of European best-practices, and new members can be mentored through this process by existing, experienced FitBack collaborators. Physical fitness is an important indicator of health in children . Accurately monitoring child and adolescent physical fitness is critical when designing effective public health interventions and strategies. This article communicates the creation process of the FitBack platform, a multi-lingual, free-for-use online health, education and information portal tool. The study's objectives are to provide a detailed breakdown of the evidence-based health-related criteria that support its unique feedback reporting system. Four methodological phases were used to create the FitBack platform. First, a review of existing European fitness databases was conducted to identify common fitness tests and methodologies within a European framework. Second, investigators collated data to create European-level fitness norms, health-related criteria, and health-oriented educational resources dedicated to improving child fitness levels. Third, guidance on how to create one's own fitness monitoring and surveillance system was created based on good practice examples. The FitBack platform was then piloted and launched based on data received from stakeholders who responded to ≥2 rounds of consultation dialogues. The final version of the online platform is detailed herein, with special focus on describing its novel health-related, child-specific fitness criteria used to provide its diverse end-users individualised health feedback. The FitBack online platform is a first-step tool that anyone can use towards creating their own standardised, person-centred, multi-national fitness surveillance system for children, bridging policy gaps that exist between current European political recommendations and individual member states, encouraging harmonious cooperation between sectors. By providing the detailed age- and sex-specific health-related fitness cut-points underpinning FitBack's health feedback, we expect this versatile digital health tool to be useful not only to researchers, but also practitioners and policy makers, as they work towards building better child fitness monitoring system infrastructures worldwide.