There are stubborn inequalities in children and young people's physical activity (PA) levels. Girls, and people from deprived areas and ethnic minority backgrounds are the least active. Inequalities in PA levels have been exacerbated by the COVID-19 pandemic (Bingham et al., 2021). The consequences of low levels of PA play out in child and adult health, wellbeing and academic outcomes. Tackling PA inequalities is at the heart of Sport England's latest strategy, Uniting the Movement (Sport England, 2021). PA leaders who young people relate to (due to similarities in, for example, age, gender, background, ethnicity) can engage the least active, as they show that PA can be for people like them, and make the young people feel comfortable. However, the UK PA workforce is largely white and male, which contributes to lower levels of PA in females from underserved groups (Sport England, 2018). The International Society for PA and Health (ISPAH) has recently published a call to action, which advocates for diversification and upskilling of the sport and PA workforce as a key component of a systems-based approach to increasing population levels of PA and reducing inequalities (ISPAH, 2020). Developing young female PA leaders contributes to positive youth development (PYD), which can build sustainable PA provision and improve the life circumstances of young females from underserved communities. Despite several young PA leadership programmes being delivered by different providers across the UK, none have been specifically designed to target underserved groups of girls, they focus on sport (rather than PA more broadly) and they are not evidence-based. This research will co-produce a framework, underpinned by PYD, for developing young female PA leaders from underserved groups (herein described as 'Leaders Like Us'). We use the terms 'female' and 'girls' for brevity purposes, but we aim to be inclusive of young people aged 16-25 who identify as female, non-binary or other minority genders. 'Leaders Like Us' can be used i) to adapt existing programmes to support uptake and delivery to underserved groups of girls, and ii) to develop new, locally-tailored programmes that benefit from enhanced quality and robustness but remain adaptable. The framework will include guidelines on how to identify, recruit and maintain engagement with young girls (aged 16 - 25) from underserved groups, outline learning outcomes for young female PA leader programmes, and provide recommendations for working with specific underserved groups. We will develop 'Leaders Like Us' through a two-phased approach, underpinned by the Double Diamond approach (Design Council, 2015). Phase 1 focuses on discovery; we will systematically map existing young PA leader training programmes, and conduct focus groups with stakeholders involved in developing and delivering programmes which target underserved groups, to understand what works, why and how. Phase 2 focuses on development. We will co-design 'Leaders Like Us' with a range of young females from underserved groups, practitioners and academic partners, through a series of workshops. We will then test its acceptability and feasibility through think-aloud interviews. 'Leaders Like Us' will help drive positive change in young leader development in practice, as it provides an evidence-based resource to support the development of local programmes that are relevant and meet the needs of females from underserved groups. This will help work towards a socially just and gender-balanced PA workforce, and ultimately promote lifelong participation in PA in girls and young women.

The communities and neighbourhoods where we grow up have a lifelong influence on the illnesses we get and how long we live. Health is about avoiding disease and having a long life, but is also about feeling well in mind and body, feeling safe, being part of a community and having things to look forward to. Many aspects of the world around us influence our health directly or influence health related behaviours. These so called "broader" determinants of health include the houses and flats we live in, the design of our roads and high streets, the availability and quality of parks, green spaces, libraries, galleries, museums, sports and recreational facilities, entertainment opportunities, places and events to connect with others, the shops and businesses around us, pollution levels, learning opportunities, the jobs available to us and whether we have enough money to make ends meet and to participate in social activities. Attempts to change health related behaviours such as unhealthy eating, drinking, smoking and lack of exercise, have met with important but limited success. For example, increased awareness of links between childhood obesity and ill health and the importance of exercise and healthy diet will have limited success if broader determinants are not also tackled. These broader determinants include, but are not limited to, the many fast food outlets that children may walk past, lack of access to high quality play and recreational facilities, sell off of school playing fields, streets that are not safe for children to walk or cycle to school, lack of high quality green spaces for exercise, shops with poor choice of healthy foods, increased screen time replacing physical activity, poor quality of school food, and, for some, insufficient income to buy healthy food. Our ActEarly approach focuses on improving the health of children in two contrasting areas with high levels of child poverty, Bradford in Yorkshire and Tower Hamlets in London. In preparation for this work we have worked with local communities, local authorities and other local organisations and have established shared priority areas for research: Healthy Places, Healthy Learning and Healthy Livelihoods. We have brought together experts in these themes with local community and local authority representatives to begin to develop a range of approaches to improving child health across these areas. For example, within our Healthy Places theme we will work together to: map local community assets and to understand how they can be improved and used by more people; develop a Healthy Streets approach and improve green space quality. In our Healthy Learning theme we will work together to develop local "Evidence Active Networks" of pre-school, school and community learning venues. These networks will help develop and evaluate a wide range of approaches to improve child health. In our Healthy Livelihoods theme we will work together on approaches such as relocation of welfare advice services to improve access, enabling parental leave, ensuring a minimum basic income in school leavers, providing life skills training and involving local communities in decisions on how to spend local authority budgets. To understand the effect of these approaches on child health we will develop strong data resources that bring together existing information from across our localities to measure changes in the local environment, health related behaviours and health outcomes. Teams of researchers will use this data and work with local communities to understand how successful our initiatives have been. We describe our emphasis on early life interventions, our highly collaborative approach and development of local data sources to enable evaluation of multiple initiatives, as the "ActEarly Collaboratory". We hope the approach will promote a fairer and healthier future for children and a global example of how to work with communities to improve health.