3.1 Stage 1: Understand the behaviour
3.1.1 Step 1: Define the health problem in behavioural terms
In Step 1 of the intervention development process, the PI defined the health problem in behavioural terms. Based on the literature, it was determined that many primary schoolchildren and older adults (65+) do not meet the PA guidelines, which has negative consequences for the health of both age groups. Additionally, it was identified that intergenerational interventions to increase PA in both generations are currently scarce, generally ineffective on the long term, include limited variation in physical activities, and often fail to target family relatives [30].
3.1.2 Step 2 and 3: Select and specify the target behaviour
Building on step 1, the target behaviour was selected and specified. Accordingly, the ‘Ages get Active’ intervention will focus on increasing co-PA (i.e., being physically active together) between grandparents and their grandchildren as the primary outcome. More specifically, the intervention aims to focus on achieving the WHO PA guidelines during leisure time activities. Increasing co-PA could lead to an increase in overall PA levels and may, as secondary outcomes, contribute to improvements in cognitive functioning, psychosocial well-being, expectations regarding ageing and quality of the family relationship between grandparents and grandchildren. Furthermore, motor competence in grandchildren and balance and mobility in grandparents can also be improved. Moreover, recognizing the broader benefits of being sufficiently physically active, including various related health benefits [31] and the potential to reduce social isolation and feelings of depression in older adults [32], stresses the importance of targeting co-PA in this intervention.
3.1.3. Step 4: Identify what needs to change
This step involved the identification of grandparents’ and grandchildren’s key barriers for engaging in co-PA and aligning them with the relevant components of the COM-B model, Capability, Opportunity and Motivation. The identified key barriers for grandparents, along with their corresponding COM-components and the related intervention goals, can be found in Table 4. These intervention goals were assigned by the PI to specific COM-B and TDF components of the BCW. Grandchildren could only indicate one barrier (physical ailments of their grandparents).
3.2 Stage 2: Identify intervention options
3.2.1 Step 5: identify intervention functions
After assigning the intervention goals to specific COM-B and TDF components, the nine intervention functions, which can help to achieve behaviour change in the target group, were explored by the PI. Three out of nine intervention functions were selected by the PI and will be focused on in the ‘Ages get Active’ intervention: education, modelling and enablement. The other six intervention functions were not selected, based on practical considerations by the PI and input from grandparents during co-creation session 5 and the meeting with stakeholders after the co-creation sessions. For example, functions like restriction (environmental restructuring) were considered impractical due to the difficulty of implementing strict rules or reshaping the physical and social environment of grandparents and grandchildren. Additionally, coercion, persuasion, training and incentivization were not selected as grandparents were already motivated and aware of the importance of (co-)PA, making external rewards of persuasion efforts unnecessary.
3.3. Stage 3: identify intervention options
3.3.1 Step 6: Identify behaviour change techniques (BCTs)
In the 6th step, BCTs were selected by the PI based on the chosen intervention functions. To streamline this selection process, the APEASE criteria were used ensuring that the most suitable BCTs were selected. Input from grandparents during co-creation sessions 1, 3 and 5 and grandchildren during co-creation sessions 2 and 4, along with the APEASE criteria, guided the final selection of BCTs to be included in the ‘Ages get Active’ intervention. The comprehensive link between the COM-B components, intervention functions, selected BCTs and adherence to the APEASE criteria can be found in Table 5 The practical implementation strategies linked to the corresponding BCT can be found in Table 6.
3.4.2. Step 7: Identify mode of delivery
In the 7th step, intervention delivery methods were explored. An intergenerational program involving six organized group-based physical activity sessions for grandparents and their grandchildren on a weekly basis with varied activities (i.e., focus on coordination, balance, condition, flexibility…) in combination with tangible tools at home and an overview of existing community-based activities emerged as an appealing and engaging delivery mode, supported by the literature and input gathered in co-creation session 4 (grandchildren) and 5 (grandparents).
3.5. The “Ages get Active” intervention
3.5.1 Content of the intervention
The result of the extensive development process was the “Ages get Active” intervention, an intergenerational PA intervention consisting of four main intervention components. These components were constructed based on the different intervention goals and their associated BCTs, which will also be referred to in the text. The four main components include:
1. Educational component
The component serves as an introduction session for the organized group-based movement sessions for both grandparents and parents of the grandchildren (without the grandchildren). During this session, grandparents and parents will receive an overview of the project objectives, expected outcomes, timeline and practical details. Additionally, information will be provided on the PA guidelines, including statistics illustrating the low number of children and older adults reaching these PA guidelines, and the associated health consequences (intervention goal 4). Moreover, a detailed overview of the other three key components of the intervention will be offered. This will include in-depth explanations of the organized group-based movement sessions, home-based activities, guidance on the effective use of the co-physical activity booklet, insights into participation in community events, and an introduction into the importance of setting and working towards SMART (Specific, Measurable, Achievable, Relevant, Time-bound) goals (intervention goal 8 and 9).
2. Organized group-based intergenerational movement sessions
The second component consists of six group-based sessions for grandparents and grandchildren, that are tailored to their specific needs. In line with the WHO PA guidelines, strength, balance and coordination exercises will be embedded in the sessions. These group-based sessions will have a dual focus. For grandchildren, the sessions will include well-structured, qualitive, and age-appropriate fundamental movement skills, coordination activities, and engagement in moderate-to-vigorous physical activity (MVPA), while for grandparents, the focus will be put upon coordination, balance, agility, and light-intensity physical activity (LPA) in combination with MVPA. This tailored approach ensures that exercises are safe and effective for both age groups (intervention goal 3). To enhance engagement and enjoyment, themed sessions (e.g., animals, countries, music) will be used, making it particularly appealing for children, which can trigger grandparents to be physically active if they see their enthusiastic grandchildren (intervention goal 7). Recognizing the high energy levels of grandchildren, the group sessions will also include activities where grandparents and grandchildren engage together in gentle, relaxing activities, such as yoga and stretching. This will provide an opportunity for both generations to unwind and find mental relaxation (intervention goal 2). The sessions will be led by the PI and guided by coaches, which are master's students specialized in movement and sports sciences. Exercises will be varied and differentiated, and the coaches will also address the specific physical needs of both grandparents and grandchildren during the sessions, thereby proactively addressing any physical ailments of the grandparents (intervention goal 1). To ensure the safety of both grandparents and grandchildren (intervention goal 3), the coaches will provide explicit instructions and guidance on how to perform the exercises safely during the group-based sessions, including techniques to minimize the risk of injuries. The sessions will be held weekly, lasting 1.5 hours, and will be conducted every Sunday morning, Wednesday or Friday afternoon in Ghent, Belgium, offering both indoor and outdoor options. This flexibility in date and location allows for adaptation to their personal agendas and the various weather conditions (intervention goal 8 and 9). Moreover, at the beginning of each session, 15 minutes will be allocated to set SMART goals in collaboration with the PI and the coaches (intervention goal 8). These personalized goals will serve as a roadmap for planning and achieving (co-)PA goals. For example, a personalized goal may involve the exploration of a nearby park together at least once a week. This goal not only encourages co-PA through walking, but also provides an opportunity to share outdoor experiences and spend quality time together. Additionally, grandparents and grandchildren will briefly discuss which individual physical activities they will each engage in separately during the upcoming week, as outlined in component 3 “Home-based activities” (intervention goal 7 and 10). Progress in achieving these goals will always be evaluated in the next session (intervention goal 8). To motivate grandparents and grandchildren in achieving their SMART goals and performing their individual physical activities as agreed upon, the PI will send a motivating message as a reminder in a WhatsApp group chat with the grandparents (intervention goal 7).
3. Home-based (intergenerational) activities
The third intervention component includes an engaging home-based approach with the aim to actively promote and facilitate (co-)physical activities for grandparents and grandchildren within their home environment, as it is not always possible to be physically active outside the home environment (e.g., no park in the neighborhood, no transportation options, bad weather conditions) (intervention goal 5). This component includes a user-friendly booklet with (co-)PA ideas that are tailored to grandparents’ and grandchildren’s specific needs, preferences and circumstances. The primary goal of this booklet is to promote a sustained commitment to (co-)PA within the home environment, beyond the organized group-based movement sessions. The booklet offers a diverse range of physical activities, categorized into two sections: co-physical activities and individual physical activities (intervention goal 5). All physical activities are categorized into themes, including coordination exercises, balance exercises and conditioning exercises. These activities vary in energy levels (intervention goal 2) and are designed to be enjoyable and accessible for both generations (intervention goal 7). To monitor progress and adherence to the intervention goals, grandparents and grandchildren (with their parents) will be encouraged to record their (co-)physical activities in the booklet. This booklet will not only serve as a record of their achievements, but also as a motivational tool, stimulating them to achieve their personalized goals (intervention goal 7).
4. Promotion of Community-Based Events
The fourth and last intervention component includes a comprehensive list of existing community events and activities in the neighborhood, which are easily and safely accessible, serving as a valuable resource to inform and engage grandparents and grandchildren in local activities focusing on co-PA (intervention goal 6). This list provides information about upcoming events, including details such as dates, times, locations, prices and descriptions of each activity. The goal is to actively engage participants in participating in these community events, fostering social engagement and creating enjoyable experiences for grandparents and grandchildren. Grandparents and grandchildren can choose and engage in activities that align with their preferences and interests (intervention goal 10).
3.5.2. Intervention timeline
The Ages get Active intervention will be implemented from April 2024 to September 2024, with a measurement period before (PRE), immediately after (POST), and during a follow-up evaluation (3 months after POST) to assess its effects. Baseline measurements will be conducted in April, post-measurements in June and a follow-up measurement will be performed in September. A combination of an effect and process evaluation will be used to evaluate the Ages get Active intervention.
3.5.3. Intervention evaluation
3.5.3.1 Evaluation of the effects
Effects of the intervention will be evaluated. The primary outcome, (co-)PA, will be measured with accelerometers (ActiGraph wGT3X-BT) in grandchildren and grandparents. Both will wear the ActiGraph pre, post and follow-up for 8 consecutive days. Grandparents will fill in a diary where they write down all the physical activities they did together with their grandchild (i.e., time, location and kind of activity). Grandparents and grandchildren will also wear an ActiGraph during the intervention period and during an organized-group based session to monitor and evaluate co-PA, intensity of PA and heart rate. The secondary outcomes; cognitive functioning, family relationship, psychosocial well-being, expectations regarding ageing and motor competence, will be measured with different tools. Cognitive functioning will be measured pre, post and follow-up with the Cambridge Neuropsychological Test Automated Battery (CANTAB) (i.e., concentration, attention, memory). Family relationship, psychosocial well-being and expectations regarding ageing will be measured pre, post and follow-up with validated and suitable questionnaires. Least, motor competence in grandchildren and mobility and balance in grandparents will be measured with field tests pre, post and follow-up.
3.5.3.2 Evaluation of the process
In addition to evaluating the intervention effects, a process evaluation will be conducted. Firstly, enjoyment during the organized group-based sessions will be measured after each session with a questionnaire. Secondly, the process-evaluation plan of Saunders for assessing health promotion program implementation will be used [33]. Thirdly, intervention fidelity will also be examined to make sure the intervention is implemented as intended [34]. Lastly, focus group sessions with grandparents and grandchildren will be organized to provide valuable feedback on their experiences. They will be encouraged to share insights, successes, and challenges encountered throughout the intervention period. Additionally, participants' perspectives on the co-physical activities, the booklet, community event participation, and the establishment and pursuit of SMART goals will be elicited. These sessions will take place at the end of the intervention, after the last organized group-based session in June 2024. The information collected during these focus groups will play an important role in understanding the intervention effects and shaping the future refinement of the ‘Ages get Active’ program, with the aim of implementing it on a larger scale. By actively engaging participants in this feedback process, we aim to make continuous improvements that enhance the intervention's impact on promoting active and healthy lifestyles for both grandparents and grandchildren.