To the authors knowledge, this is the first time that practitioners, policy makers and researchers who understand the powerful driving agents of school systems and teacher and pupil physical activity behaviour, have co-designed a whole-school physical activity framework from initial conception. The underlying DDDA previously used to develop high-quality systems change in multiple healthcare settings, was used to develop an innovative practice and evidence-based framework that meets the needs of each stakeholder as well as the important constituent parts required for effective and sustainable implementation. To achieve such an outcome, it was essential for the design process to incorporate multiple stages of divergent and convergent thinking to optimise the final framework by challenging and refining initial views. As a result, CAS has high face validity, and because it has been endorsed by a range of professional groups, it also demonstrates professional and contextual credibility.
Implications for practice
CAS confirms the large number of components that must be addressed so schools can evolve into adaptive sub-systems with physical activity at the heart of their provision. While little is currently known about the inter-relationship between the different elements - and CAS does not identify those with the greatest effect - the importance of whole-school ethos and practice was established. Importantly, CAS refutes the notion of deploying single-element interventions; it reinforces the need to create systems change through school leadership groups. Such change has already been identified within current research and frameworks [21, 56], yet remains elusive within the school environment [52, 57].
Framing every school as a unique, complex adaptive sub-system, CAS establishes the importance of whole-school ethos and practice. This is consistent with Meadow’s  12 levers of influence where value-based leverage is central to creating sustainable change; this is best achieved by (i) identifying systems goals, (ii) understanding the paradigm guiding the design of the new system and (iii) encouraging a shift in the decision-making paradigm as new challenges arise. The dynamism and complexity outlined by the potential interplay of so many facets helps to put flesh on the bones of the notion of ‘compensating feedback’, which explains why powerful sub-systems, like schools, resist powerfully . To create change, CAS confirms that so much needs to be made right. This was most evident in the interactions between the five stakeholders within the social and physical environments; these are levels that many physical activity initiatives overlook .
Of great surprise, the seven opportunities were positioned at the lowest level, suggesting not only their fragility but also the importance of higher-level factors. While an emerging body of research recognises the need for higher level engagement, this is contrary to current practice which is often characterised by limited engagement with different levels of the school system . Consistent with previous socio-ecological frameworks [21, 56], the CAS framework reminds all stakeholders to move beyond simple interventions to become ‘systems thinkers in action’ ; this reminds practitioners to address at least three levels of their school system; the grand system (e.g., Schools), local system (e.g., a single school) and system parts (the mechanisms of individual events/provision) .
The old counselling adage of ‘the map is not the territory’ applies to CAS; CAS does not identify the specifics of any individual school. Change leaders who may act as whole-school physical activity champions - as seen in the comprehensive school physical activity programme and Action Schools BC frameworks [21, 56, 62] – can use the framework to develop a bespoke process to fit the unique requirements of their school. With over 20 active components, physical activity champions will require a system change plan. That plan will identify the priorities and modify the existing structures to create change. Perhaps this is the primary instance where all of the components have been collated. CAS reveals the complex challenges facing these champions, especially primary school teachers and senior leaders with little expertise in physical education delivery, let alone systems change for whole-school physical activity . Given this complexity, it makes sense to address these issues in initial teacher training programs and in-service training (CPD); in-service teachers will need to embed the skills that establish (i) the capability, opportunity and motivation for systems change and (ii) systems change that secures whole-school physical activity. Importantly, the CAS framework is the first that embeds a modern, eclectic behaviour change framework (COM-B) . The integration of the COM-B framework reflects a need for accessible language while retaining an underlying complexity of 21st-century behavioural decision-making.
Schools and wider stakeholders can use the CAS framework to promote self-reflection by mapping current provision and identifying underserved components. Maintaining the co-production process, initiatives should be implemented with, rather than on schools. At this stage, it is essential that children, who were not engaged in our co-development process, become equal partners in identifying, developing and implementing future interventions. To support schools, an evidence-based audit tool would emphasise the importance of all CAS framework components, especially whole-school ethos, practice, policy and vision; components often neglected in previous interventions. While CAS was developed within a specific UK context, its flexible nature allows replication elsewhere. Moreover, while secondary (high) schools may benefit from using CAS as a guiding framework, it is important that they establish face validity and acceptability as initial priorities. Perhaps the first step is to identify early adopters and seek to test and learn new/novel processes for creating whole-school practice and ethos aligned to physical activity.
Implications for policy
The top of the framework reinforces the importance of creating both horizontal and vertical alignment of people, organisations and policies; this will help ensure that all changes move in the same direction. Vertical alignment reflects the need for key issues to be reinforced throughout all processes down to the level of individual pupils and moments within the school day. In contrast, horizontal alignment requires a common shared vision within each level of the system (e.g. national organisations and government departments, e.g., in the UK of Health & Social Care, Education and Digital, Culture, Media & Sport). Misalignment between horizontal and/or vertical issues is likely to create unhelpful friction that challenges the creation of a clear whole-school ethos , weakening any resulting interventions. To enact policy and evolve current practice, CAS not only provides a checklist for change agents but also a template for the development of a healthy schools rating scheme. Multiple schemes currently exist [64, 65], yet few reflect the full range of influential components. As a result, they may lack the detail required to promote effective and sustainable physical activity initiatives.
Government education, health and sports departments that value physical activity can use the CAS framework to drive strategic change within the education system. The use of one central framework, for the promotion of whole-school physical activity, can drive combined efforts across all UK government departments and policies. Such alignment, as previously stated, is central to creating a sustainable adaptive system that promotes one vision of creating an active school; CAS provides this opportunity. Furthermore, bodies that hold schools to account for educational standards (e.g., Office for Standards in Education in the UK) can utilise CAS as a tool to support schools to embed physical activity throughout the school day. In addition, national and localised sport and health organisations that set strategies for grassroots sports and health improvement can use CAS to highlight their role in whole-school physical activity. CAS will enable organisations to align their provision and develop more efficient and sustainable practises in schools and their local communities.
Implications for research
The CAS framework provides researchers with an understanding of the multiple components that need to be addressed to create and evaluate whole-school physical activity interventions. It emphasises the need for researchers to move beyond push approaches and co-develop interventions with multiple stakeholders within the school setting from conception . The challenge for researchers resides in creating programmes that create systems level change within schools. CAS highlights the need to focus on school-level change, not just the interventions within the seven opportunities . Further, this study provides a template for physical activity researchers in the UK and beyond to adopt experience-based co-design approaches, specifically using the DDDA approach.
Strength and limitations
A particular strength of the CAS framework is that it is, to the authors’ knowledge, the first to deploy a co-development methodology with multiple stakeholders holding deep and wide experience of UK school systems. While pioneering, the final framework is based on the vision of a specific group of stakeholders and this specific process. Involvement of further stakeholders (parents, school nurses etc) or indeed alternate “experts” may have yielded different outcomes. Yet, CAS reflects insights from the UK and select westernised high-income countries meaning it is likely to provide a reasonable reflection of the components of a whole-school physical activity framework within similar countries and education systems. In addition, the flexibility of CAS enables contrasting school systems to prioritise different components with the framework to meet curricular and logistical needs.
This is the primary instance that an experience-based co-design process - the DDDA - has been used within the whole-school physical activity field. Recognising our relative inexperience in design, and notwithstanding that the paper provides a powerful template for future projects, improvements may emerge from a more refined design process. Further, while the framework provides a map, it does little to identify how the respective parts interact, nor does it specify the optimal sequence(s) or interactions that need to take place . Future research and practice collaborations will need to investigate the implementation of the framework.