The research was conducted within a critical realism paradigm, which acknowledges both the existence of objective reality (ontological realism) and that co-designers’ and researchers’ understanding of that reality is situated and relative (epistemological relativism) [30]. The study used an exploratory, sequential, participatory research design [31,32] using multiple methods to iteratively inform resource co-design. The co-design process involved physiotherapist-researchers with experience and expertise in X-gen PA, along with neurodiverse or developmentally diverse children and the parents of these children. The physiotherapist-researchers contributed to the co-design process knowledge of considerations regarding X-gen PA gleaned from families more broadly based on prior research with families [16,18] with their own families’ lived experiences with X-gen PA and their professional experiences. Participation and contributions of neurodiverse and developmentally diverse children and their parents in the co-design process enabled consideration of a range of additional issues for X-gen PA that may not have been as prevalent or as strongly recognized in many of the families involved in prior X-gen PA research. Children and parent co-designers attended 2 to 3 co-designer workshops where they trialed and provided feedback and suggestions on key elements of 2 X-gen PA prototype resources that were initially drafted by the physiotherapist-researchers, based on their prior understanding of X-gen PA (Figure 1). Additionally, child and adult advisory groups were established to provide guidance and feedback on the co-design approach (Figure 1). Both quantitative data (from surveys of participants) and qualitative data (child and parent co-designer suggestions and researcher observations) from workshops were collected and analyzed in this multimethod co-design research.

This study took place in a rural Local Health District (LHD) in NSW, Australia. Co-design workshops and child advisory group meetings were held in local library meeting rooms, while the adult advisory group meetings were online.

As a first step in the sequential co-design process undertaken in this study, 2 evidence-informed prototype X-gen PA guidance resources were drafted by the physiotherapist-researchers (KF, KA, and RP) in the research team. These drafts provided families participating in the co-design study with evidence-based prototypes to trial and critique, thereby facilitating a sequential approach to co-design in which the initial contributions of the practitioner-researchers, resulting in prototypes, provided a foundation for the contributions of children and parents and subsequent contributions of the researchers. Similar sequential approaches to co-design, which integrate research evidence and clinical and expert experience with lived experiences of consumers through a sequential co-design process, have been described elsewhere, for example, the Framework for Co-Design of Clinical Practice Tools [31]. A further example is the bidirectional strategy used in the co-design of a self-compassion mobile health intervention for people with cancer, which enabled the merging of “top-down” (research evidence based and clinical expertise based) and “bottom-up” (lived experience based) inputs in the co-design process [32].

In this study, the drafted prototypes took the form of booklets that provided families with guidance on building family capacity for planning and adapting PA to the X-gen PA context. Drafting of the prototypes was informed by evidence accumulated from previous research [16,18] and the following frameworks and behavior change theories: the International Classification of Functioning, Disability, and Health [33], family-centered practice [25], self-determination theory [33], socioecological frameworks [20], and strengths-based practice [1].

The first of these prototype resources, Doing Physical Activity Together, described the purposes behind X-gen PA and experiences of children and parents with X-gen PA, discussed current evidence of the benefits of being active together, and provided examples of types of PA that families might try doing together. The second prototype resource, Planning Physical Activity Together, covered aspects families might consider when planning a PA session together. It also guided families through a postsession review, through which they could identify aspects of the X-gen PA session that each participant liked and aspects they might wish to change in future PA sessions.

The prototype resources sought to assist autonomous experiences by supporting children’s and parents’ rights to take part in planning and choosing aspects of X-gen PA [34]. Competence was addressed in the Planning Physical Activity Together prototype [33], which stepped co-designers through every aspect of planning an episode of PA together. In addition, the prototypes provided families with a common language to plan and discuss their X-gen PA. It was anticipated that this planning process would enable children to be active participants in decision-making and that the resources would build capacity for planning and adapting PA across both generations, which would be mutually reinforcing. Three quotes from children and parents involved in preceding X-gen PA research and suggestions from that prior research for X-gen PA were included in You might like to try sections of the prototypes to provide ideas for families and promote norms for X-gen PA. Two Australian First Nations mothers were paid as consultants to examine the initial proposed text in the 2 X-gen resource prototypes and provide feedback on their cultural appropriateness. No changes were identified as being needed by the 2 Australian First Nations mothers. This suggested that the prototypes were culturally safe for use by Australian First Nations families, should they choose to participate in the co-design process.

Child and parent co-designers subsequently commenced engagement with the prototype resources by using the planning resource to plan a session of PA together. This approach allowed all co-designers, irrespective of their experience of X-gen PA, to take part in the co-design study, as there was no requirement for previous experience of X-gen PA. Further details are provided below of the extensive involvement and contributions of children and parents in the subsequent stages of the co-design process.

Two researchers (KF and KA) facilitated all co-design workshops involving children and parents. Both were experienced physiotherapists, with more than two decades of experience working with children and families, as well as experience conducting research workshops and focus groups and with X-gen PA. The study involved a partnership with the Pediatric Department of an LHD, a private rural pediatric clinic, and a primary health network. The partners assisted with recruitment and provided advice for the project through representatives in project planning and on the adult advisory group. An experienced primary school learning support officer was recruited into the role of child voice facilitator and advocate (CVFA). The CVFA was a dual role created to provide both independent (nonresearcher) facilitatory support to the child advisory group and an advocacy role for the child’s voice at adult advisory group meetings.

Purposive sampling was used to invite and secure the participation of a diverse group of families who would likely use the co-designed resources. Pediatricians identified neurodiverse or developmentally diverse children aged between 5 and 12 years who also met other eligibility criteria for participation. The parents and carers of these children were subsequently informed about the study, and both the parents (or carers) and children were invited to participate. Exclusion criteria were those with a health condition that severely limited PA participation and family members who required an interpreter to take part. Parent consent and child assent for participation were obtained.

To acknowledge their time and expertise, child co-designers were given a suitable piece of PA equipment, and parent co-designers and CVFA received a credit card voucher following participation in each workshop or advisory group.

The co-design research approach was chosen to ensure that both child and parent voices, reflecting their lived experiences, contributed to the final X-gen PA guidance resources, together with the evidence-based understandings and lived experiences of X-gen PA among the researchers. Lundy’s model of participation, encompassing the 4 elements of space, voice, audience, and influence, was used to inform the co-design research approach [27]. The checklist developed by Ireland’s Department of Children and Youth Affairs [35] was used by the researchers to aid reflexivity on all elements of the approach (Multimedia Appendix 1).

Data collection periods involving participating children and families were determined by co-designers’ preferences and availability and occurred during the first 3 school holiday periods in 2024 (Table 1), with phase 1 occurring in January, phase 2 in April, and the final child and adult advisory group meetings (Table 2) occurring during the July 2024 holiday period.

Parents completed a short demographic survey at the beginning of workshop 1. The child and parent co-designers used the initial planning prototype Planning Physical Activity Together to plan a session of PA together, while a researcher observed and provided advice where appropriate. Child and parent co-designers left with copies of both prototypes. They returned following the implementation of their plan for an X-gen PA session. Achievements reported by the child and parent co-designers in completing X-gen plans were recorded, along with their initial experiences of using the resources and impacts they reported the resources had on their understandings of planning and doing PA together. Child and parent co-designers then provided feedback and gave their suggestions on the 2 prototypes. In phase 2, separate concurrent child and parent workshops were conducted, and co-designers were asked, as part of a small post–co-design survey, if using the resources had changed the ways they (parents and children) were active together and to evaluate the co-design approach (Table 1).

All child and parent co-designers were invited to join either the child or adult advisory group, respectively, to oversee the project and provide advice on the co-design approach (Table 2). Three child advisory group meetings were held during the research period. Adult advisory group meetings were held after each child advisory group meeting. Child advisory group meetings were facilitated by the CVFA (with online support from a project officer). The CVFA also attended adult advisory group meetings in their advocacy capacity, telling the adult advisory group what the child advisors wanted them to know and providing independent, nonresearcher representations of the child’s voice, as requested by the children in the child advisory group. The CVFA reported back from the adult group to the child group via the children’s parents’ email addresses. Adult advisory group meetings included a parent co-designer, the CVFA, a pediatrician, a data support officer from the primary health network, and the physiotherapist-researchers involved in the project.

Advisory group members were invited, during the second and third advisory group meetings, to comment on changes made to the prototype resources in response to data gathered in the co-design process. Child advisors watched a short video of how researchers had responded to changes suggested by child co-designers. The CVFA invited child advisors to then score how well the changes matched what child co-designers had told researchers, using a 5-point smile rating scale. They were then invited to say why they had given those scores.

Adult advisory group members were provided with tables, which listed all comments from all co-designers and all observations from researchers, together with the results of initial data analysis and any related changes made to the prototype resources. Subsequently, a brief overview of key changes made to the prototypes was provided during adult advisory group meetings before the advisory group members were invited to comment and ask questions. Adult advisory group members (excluding the physiotherapist-researchers) were invited to evaluate the co-design approach via a survey after the last advisory group meeting.

A reporting checklist was used to ensure that there was comprehensive reporting of the co-design approach while noting that exact replication is not an aim in the reporting of participatory approaches because they should be adapted to the specific context [23] (Multimedia Appendix 2).

All co-design workshops were audio recorded and transcribed. All co-designers’ suggestions and researchers’ observations were tabulated and counted. Researchers met regularly during the data collection period to discuss all suggestions and observations, reaching a consensus on amendments to be made to the prototype resources in response to this feedback. Conventional content analysis (as described by Hsieh and Shannon [37]) was used to group suggestions and observations of all co-designers into themes, and a thematic analysis was completed on transcripts of workshops to identify key themes from participants’ experiences, recommendations, and discussions, using the 6-phase approach to thematic analysis as described by Braun and Clarke [38]. Reflexivity during content and thematic analyses was supported by regular meetings between researchers, which allowed consideration of themes and alternate explanations. Demographic and evaluation surveys were analyzed using descriptive statistics and content analysis, as described earlier.

At the end of the study, co-designed versions of the resources were finalized, and a graphic designer was used to compile the final co-designed resources. An infographic was created to provide feedback to participants and distribute information about the study [39], and a website [40] was created to house and make publicly available the final co-designed resources and gather further feedback on them.

Ethical approval for this study was obtained from the Sydney Children’s Hospital Network Human Research Ethics Committee (HREC) (protocol 2023/ETH00995) and Charles Sturt University HREC (protocol H23804). Consent and child assent were obtained from all co-designers, including consent for publication.

Thirteen neurodiverse and developmentally diverse children (girls: n=6, 46.2% and boys: n=7, 53.8%, age range 5‐11, mean 8.6 y, SD 1.79 years) and 12 parents (mothers: n=9, 75% and fathers: n=3, 25%) from 9 families took part in the co-design study. Ten (83%) of the 12 parents answered a prestudy survey. All parents reported that they had never previously been given resources or advice on being active with their child. Further demographic information is listed in Table 3.

All child and parent co-designers reported they were able to complete their planned session of X-gen PA. A parent said:

Families noted the prototype planning resource helped them to organize X-gen PA and gave them a structure and language to debate what the episode would look like by considering all aspects of it. A father described how the prototype resource was used successfully as a reference to cease the frequent rule changes that their child tended to impose:

A couple of families had to adjust their plans, and they reported that these adjustments were accommodated without difficulty. For example, a mother said:

There was consensus that the prototype resources were useful and user-friendly:

Families noted that the prototype resources included aspects of X-gen PA they had not considered, such as physical and emotional safety and stopping in the prototype planning resource. And a parent noted the following about the prototype doing resource:

Children said they “liked planning” and that the prototype resources were “good” as they gave them “different ideas of what to do.” The prototype planning resource encouraged co-participation in PA, as evidenced by one parent who observed that:

There was consensus among families that using the prototype planning resource allowed children to know exactly what was happening. Using the resource reduced confusion and questions from children, which allowed all child and parent co-designers to have a better experience. For example, one mother said:

Children concurred, for example, one child said:

Some elements of X-gen PA covered in the prototype resources families had not considered planning before. For example, how to do the activity, managing emotions, and stopping. Families noted that planning improved their engagement and experience:

And a child said: “I like having rules because then we argue less.” Parents agreed, noting that planning enhanced their enjoyment by reducing arguments and allowing them to go “at a pace that works for them.”

In the second co-design workshop, some children also demonstrated an appreciation of how managing emotions could be used during other PA. For example, a child said:

Likewise, child and parent co-designers commented that they found the stopping section useful but had not considered discussing or planning this aspect before. For example, a parent said:

The importance of planning this aspect was underlined by the wide variation between child and parent time expectations. For example, a child said: “I could spend the whole day doing this.” Parents noted how having an end point that was clear helped their children. One parent noted that it helped their child engage in the activity for longer periods, and another said:

Parents also observed that knowing when PA will end helped them engage more fully with their children and the “confidence that it will end before everyone becomes tetchy and tired.” This allowed the activity to end on a positive note, without conflict.

In total, 62 changes were made to the prototype guidance resources during the co-design process. Tables in Multimedia Appendices 3 and 4 detail the 35 changes suggested by child and parent co-designers and 27 changes made based on researcher co-designer observations. Textbox 1 provides a summary of the key changes from among these.

Five children and 3 parents (n=8) answered a post–co-design survey. Six of these co-designers (children: n=3, 37.5%, parents: n=3, 37.5%) answered yes to the abovementioned question. One child answered no, and one child answered don’t know. Child and parent co-designers were invited to tell us more. Table 4 provides the themes and related examples arising in responses from child and parent co-designers.

This exploratory co-design study identified ways to increase usability and acceptability of guidance resources intended to increase family knowledge of how to plan and engage in PA together and evaluated the co-design approach it used. An asynchronous approach to co-design was taken to allow the development of theory-informed prototypes for families to trial and critique [41]. Key changes recommended by children, parents, and researchers to optimize the resources included changing the ordering of the planning resource to reflect the way that most families used it, adding a hard words section to aid readability, support to normalize that no-one wins all the time, additional examples of the types of PA families could do together, and assistance for negotiation among families to ensure that the planned PA was mutually desirable.

The secondary aim of the study was to evaluate the co-design approach. Overall, child and adult evaluators perceived the co-design approach to be appropriate and responsive and identified several elements of the co-design methodology that facilitated child and parent voices and increased methodological rigor. For example, the use of a CVFA to facilitate child advisory groups enabled safe spaces for children to contribute and evaluate changes made to the resources while ensuring independence and transparency of this aspect of the evaluation. Findings from the child evaluation and researcher observations resulted in 2 suggestions for co-design researchers to consider when conducting co-design research with children, which are discussed further later in this section.

Previous research has found that parents are already convinced about the physical health benefits of regular PA for their child but that has not changed their behavior in supporting their child’s PA [42], and PA participation rates in children are still low worldwide [6]. It is also likely that some parents, who are not regularly active themselves, may not have the PA vocabulary necessary to enable, and undertake, successful episodes of PA with their children. Parent co-designers in this study discussed how the resources encouraged them to consider aspects of doing PA with their child that they had not considered before, such as how engaging in PA together supported their child’s emotional and social development. It is hypothesized that the final co-designed resources [40] may provide families with greater insight into the wide range of health and well-being benefits of being active together. The resources were also written for both PA partners (children and their parents) to use together, as it is further hypothesized that planning and talking about PA together may influence family PA behavior and support for PA within families. However, both hypotheses will require further investigation with larger numbers of participants.

None of the participating families had previously received resources or advice on parents being active together with their neurodiverse and developmentally diverse children. The small sample size of this study means that this finding should be interpreted with caution, but it nonetheless is concerning because PA is an important intervention for these child populations [10]. Social PA interventions, such as X-gen PA, not only provide opportunities to practice physical skills and gain physical health benefits but also offer opportunities to practice prosocial skills, such as communication skills, taking turns, and self-regulation [10,43]. Provision of information to support families with neurodiverse and developmentally diverse children to take part in positive X-gen PA experiences is required. Development of paper-based or online resources, such as those created in this study, provides one possible way to deliver this support. Some families suggested that accessing the information via an interactive app would be fun, but it is acknowledged that the development cost and subsequent subscription costs of such an app might limit equitable access by excluding lower-income families [44].

The findings of this study suggest that the planning resource may help families consider together what obstacles they need to overcome to be active together. Importantly, parents reported they enjoyed their subsequent planned episodes of X-gen PA, indicating their children asked fewer questions and were more receptive to stopping PA at the end of an episode as planned, allowing for calmer experiences of X-gen PA and greater confidence that episodes would end without conflict. Basic psychological needs theory [45] may provide further explanatory insights into these experiences of success. The resources addressed all 3 needs that underpin the sustainment of intrinsic motivation for a behavior—relatedness, autonomy, and competence [45]. For example, planning stopping meant that children and parents gained insights into the often substantial differences between child and parent time expectations, resulting in conversations to plan mutually agreed-upon time frames for X-gen PA. Stopping of episodes of X-gen PA has previously been noted in the literature as an aspect of X-gen PA that children who were neurotypical found frustrating due to greater parental control over the cessation of a PA episode [18]. Creating a structured environment for children with neurodiversity, such as planning PA, has been identified as a key strategy to help children with neurodiversity manage their behavior [46]. Planning stopping also gave children with neurodiversity knowledge and preparation time to transition from one activity to another, which can help children with neurodiversity manage their emotions [46].

Previous parenting research has found that planning PA opportunities was identified as a key self-regulation strategy that parents who identify as an active parent perform for their family [47]. Research suggests that both role and social identities play a part in maintaining health-enhancing behaviors such as PA [44,48]. Role identity research has found a positive link between PA frequency and having a strong exercise identity [49]. Social identity theory acknowledges that people identify themselves by both their personal identity and a wide variety of social identities [49]. Thus, it is hypothesized that encouraging and supporting children to have both a voice and influence over the child-parent PA partnership may positively influence both a child’s identity as an active person and foster a shared “active family” identity more than resources directed solely toward parents and carers, in which children are assumed to be the passive recipients of parental decision-making.

Two recommendations for family co-design have emerged from the process evaluation of our exploratory co-design study. First, it is important to remind child advisors at the beginning of each child advisory group meeting why children’s voices are important to hear [27,28] and of the purpose behind the child advisory group (eg, terms of reference). We note that establishing agreed terms of reference has been identified in recent research on co-design studies as one factor that may enhance co-designer cooperation and understanding of their roles as co-designers [50]. Second, this study found that communicating to children via their parents’ email addresses did not ensure that child advisors were provided with information about research progress and thus we are unable to determine whether child co-designers saw the infographic depicting the research outcomes that was written for families [39]. The HREC approved the researchers to communicate with the child co-designers via their parents’ email addresses, and we acknowledge the importance of ensuring children’s safety and privacy. However, not closing the communication loop with children has been identified in previous research as a source of frustration by children [27]. Our study suggests there may still be a role in sending out research summaries by mail, perhaps addressed to the whole family, to increase the likelihood of children accessing research outcomes. Previous research has found that children enjoy receiving research outcomes in the mail and suggest sending research in multiple formats, such as summaries, coloring books, and posters [51].

The small number of co-designers and advisory group members in this study was recruited from a single rural Australian LHD, using a purposive sampling approach. We acknowledge that readers will need to determine the transferability of our findings to other populations; thus, we have provided detailed methodology, including descriptions of settings and participants. We hope our transparent approach will allow readers to consider the relevance of the study’s findings to other populations and contexts.

Fewer child and parent co-designers took part in the second phase than in the first phase of the study. A gap of two and a half months (school term) between phases is likely to have contributed to this reduction in numbers. In future research, we recommend, where possible, recruiting more child and parent co-designers to reduce the impact of attrition [51] and completing studies without such long time gaps to maintain momentum and interest. However, it should be noted that we used holiday periods because parents informed us in this study that engagement was more likely during holidays, as term-time schedules are too busy. As this study was conducted in Australia (southern hemisphere), it was not possible to conduct the study in one (summer) holiday period due to the impact of Christmas during this time, but conducting the study over a continuous 6-week period would have been ideal. It should be noted that the reduction in engagement in the second phase of the study subsequently impacted the number of children and parents who provided an evaluation of the co-design approach at the end of the study, as child and parent co-designers were invited to complete paper-based evaluations at the end of the second phase workshop. Future studies could also consider a continuous evaluation approach through the use of a short survey at the end of each workshop. Finally, the possibility of desirability bias should be noted. Steps were taken to address this risk by empowering co-designers and advisory group members, such as by employing a nonresearcher (the CVFA), doing activities that promote collaboration to disrupt power hierarchies (eg, playing games and anonymous feedback) [52], and use of multiple methods to provide different ways for co-designers to collaborate and express themselves.

The final co-designed resources are freely available under a Creative Commons License [40]. Further research is needed to test the usefulness of the co-designed X-gen resources in a broader rural population. It is suggested that such research could examine the impact of the resources on family PA literacy, family cohesion, and PA identity, and their use during holidays rather than their impact on an individual’s weekly PA total.

In this study, child and parent co-designers provided multiple suggestions to improve the usability and acceptability of guidance resources that had been compiled by experienced physiotherapists, underlining the importance of consumer involvement in resource design. The co-design methodology supported discussion and planning of X-gen PA among rural families with neurodiverse and developmentally diverse children. Future research is needed to evaluate whether these resources can positively impact family PA behavior in the longer term and across broad populations. Evaluating co-design approaches is an important way to provide transparency of the processes involved and to protect consumers against tokenistic co-design approaches. This study highlighted the need for consideration of how to convey study findings to child co-designers.