Theoretical basis
The Family Move app incorporated multiple health behavior theory constructs and strategies. The major source of theoretical guidance for the app comes from the social cognitive theory (SCT) which posits that people learn by watching others through observation, imitation, and modeling [24]. It also emphasizes the reciprocal relationship of personal (e.g. financial and weight problems) and environmental factors (e.g. limited availability and accessibility of PA resources) with behaviors (e.g. PA behavior). Evidence suggests that observational learning, self-regulation, psychological states, and environmental characteristics are determinants of behaviors [25]. A key psychological determinant is self-efficacy which refers to “beliefs in one’s capabilities to mobilize the motivation, cognitive resources, and courses of action needed to meet given situational demands” [26]. Another psychological determinant is outcome expectations defined as “one’s judgement of the likely consequences that will occur as a result of performing, or not performing, a particular behavior” [27]. External factors such as incentive motivation and use of special app functions to engage participants can also influence behaviors [25].
The SCT has been used to guide the development of website intervention for promotion of PA in young adults [28]. This study adopted a similar conceptual framework. Figure 1 illustrates the model describing how the Family Move app functions affect the target outcomes in children through their effects on different SCT constructs:
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Self-efficacy: Simple exercise moves and a scoreboard documenting user effort and participation in the form of accumulated points were included to increase user motivation and confidence in performing the exercise moves.
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Outcome expectations: Joyful interactions between two people (demonstrated in the exercise video) and specific fitness benefits (in the form of an audio instruction) were used to enhance positive outcome expectations in users.
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Self-regulation: A Personal Record page was included to allow users to monitor and regulate their own performance with reference to peer performance.
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Facilitators: Gaming elements such as point system and reward system are incorporated into the Family Move app to increase user engagement. Push notifications and text messages about exercise benefits are also used to engage users to use the app
In addition, we also used other motivational elements and principles such as developmentally appropriate exercises, gamification, professional endorsement, and data privacy to attract people to use the app.
Development process
The development and testing phases of the Family Move app were conducted from August 2016 to May 2017 by a collaborative team of physiotherapists, clinicians, fitness trainers, health promotion information technology experts, and graphic designers. The Family Move app incorporates coaching videos with gaming elements such as points, level system, and scoreboard for tracking progress among users [29]. Given that our target participants may have varying degrees of physical abilities and fitness levels, the expert panel decided to develop a staged intervention with short bursts of exercises (i.e. 30 s per exercise move) at three difficulty levels (basic, intermediate, and advanced). During August–September 2016, a list of simple stretching and aerobic exercises stratified by child age (6–10 years and 11 years or above) were selected and modified to partner exercise format by PA specialists. In the subsequent pilot course, 14 parent-child pairs tried to perform the shortlisted exercises under the instructions of a certified fitness trainer. During the course, parents and children demonstrated high interest in basic aerobic exercises and enjoyed the parent-child interaction time. However, parents found stretching exercises difficult to perform because of the physical demands for muscle strength and flexibility. They also expressed concerns over extension exercises because of limited living space. Based on these feedbacks, the exercise moves were further adjusted to meet these needs of parents and children before filming the moves.
The exercise video production process began in December 2016. We recorded a total of 18 exercise moves which were demonstrated by a certified fitness trainer and a child with good athletic skills. During post-production, the coaching videos were further edited with the addition of background music, timer, color correction, and subtitles highlighting the health benefits of the exercise move. Each in-game level would have a warm-up exercise clip, four independent exercise move clips, and a three-minute challenge clip that allows for interval training [30]. The details of the coaching videos are provided in Additional File 1.
After viewing a coaching video in the app, users would automatically receive points, with more points being awarded to more difficult moves. Furthermore, to create a competition context, users would be ranked by the total number of points earned through viewing the coaching videos. The top five frequent users’ scores would be displayed anonymously in the in-app scoreboard. In addition to gaming elements, push notifications and text messages would also be used to enhance user motivation for participation. Based on the level of usage recorded in the Central Management System (CMS), psychoeducational text messages can be tailored and sent to different groups of users (i.e., logged-in and active users, logged-in yet inactive users, and never logged-in users) on a regular basis. For example, messages for inactive users would focus on the fun parts of the app and associated benefits (e.g. Forward and backward lunge can serve as balance training to strengthen the muscles of thigh, leg and hip; the demo clip is now available in FAMILY MOVE!), whereas messages for active users would focus on encouragement by acknowledging the user’s good progress (e.g. Good job, you are making excellent progress!). Screenshots and details of the functions of the Family Move app are provided in Additional File 2.
Basic software requirements were also confirmed during this development period. For example, it was confirmed that the app would operate in devices running iOS 9.0–10.0 and Android 4.4.2–6.0 and require username and password for access. This user registration function is needed to record a user’s login time and usage. These records can be retrieved from the password-secured CMS where administrators can configure, manage, and monitor user accounts.
Study design
A pilot study using the pre-post assessment method was designed to examine changes in children’s HRQOL, psychosocial wellbeing, and PA levels after the Family Move app-based intervention. The intervention lasted 8 weeks with three assessment time points (baseline, 1-month and 6-month follow-up).
Ethics
Ethics approval was granted by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (UW 17–179).
Study population
Families with at least one child aged 6 to 15 years were targeted, as children in this age period should develop the physical competence to perform exercise moves and still enjoy spending time with parents. Eligible families must be ethnically Chinese and live in Hong Kong. In addition, the parents must have a smartphone that can download and install apps and provide consent for themselves and their children to participate. To maximize the social diversity of our sample and ensure adequate sample size, we recruited participants from local schools and community programme through convenience sampling. Specifically, we approached 19 local schools, three of which expressed interest to help with recruitment by distributing relevant study information to their students; then our research assistant briefed the interested students about the intervention through phone calls or text messages. Meanwhile, we also advertised our study in the newsletter of the community low-income family support program which was conducted by our team in partnership with a philanthropy foundation, the Kerry Group Kuok Foundation [31]. Given that the effect size of d = 0.3 is usually considered as the minimal clinically important difference in HRQOL [32], the power analysis showed that a minimum of 34 parent-child pairs would be sufficient to detect such effect size with 80% power at the 5% significance level.
Data collection
Parents of eligible children were given information about the objectives and procedure of the study. Interested parents subsequently provided written consent separately for themselves and for their children to participate in this study. Instructions with the link to download and install the app onto their smartphone and the family-specific login information were sent to parents by text message. Parents were asked to complete a set of parent-proxy report questionnaires on their children’s HRQOL, psychosocial wellbeing, and PA level at baseline and 1- and 6-month follow-up. They were reminded to mail it to the research team office within 2 weeks after distribution.
Intervention
Each participating family had an account in the Family Move app. The login information was sent to the parent by text message. During the 8-week intervention period, participating families received parent-child exercise training through the Family Move app by stages (i.e. basic training in the first 2 weeks, intermediate training in the third and fourth week, advanced training in the fifth and sixth week, and no training restriction in the final 2 weeks). Each coaching video included Cantonese audio instructions that guided parent participants to perform the exercise move with their children while watching and encouraged them to incorporate the move into their daily routine. Prior to the intervention, all participants were informed that families who earned at least 5000 points over the intervention period would be given a gift worth HK$50 (US$ 6.4) for their active participation in the intervention.
Measures
Health-related quality of life
The Chinese Child Health Questionnaire – Parent Form – 50 (CHQ-PF50) was used to assess HRQOL. The tool includes twelve domain scales (General Health, Physical Functioning, Role/Social Limitations – Emotional/Behavioral, Role/Social Limitations – Physical, Bodily Pain/Discomfort, Behavior, Mental Health, Self-Esteem, Parental Impact – Emotion, Parental Impact – Time, Family Activities, and Family Cohesion) and two summary scores (Physical Summary Score and Psychosocial Summary Score) [33]. Higher scores indicate better HRQOL.
Psychosocial wellbeing
The Chinese Strength and Difficulties Questionnaire (SDQ) was used to assess psychosocial wellbeing. The tool includes five subscales of emotional symptoms, conduct problems, hyperactive/inattentive problems, prosocial behaviors, and peer relationship problems [34]. Higher scores indicate more problem behavior for all except the prosocial behavior score. The scores of the four problem behavior subscales can be summated to a total difficulties score.
Physical activity level
The International Physical Activity Questionnaire – Short Form - Chinese version (IPAQ-SF) was used to assess physical activity level. The tool includes seven questions on the frequency and duration of time spent in physical activity in the past 7 days [35] to calculate total weekly PA level expressed in MET-minutes/week.
Family move app usage
The Family Move app usage was indicated by the total number of points earned through viewing the coaching videos in the app over the 8-week intervention period. This usage information can be retrieved from the CMS. Higher points indicate more frequent use of the Family Move app. We categorized participants as users (those parent-child pairs who had viewed at least one video clip during the intervention period) and non-users (those parent-child pairs who had never viewed a coaching video during the intervention period).
Data analysis
All analyses were carried out using IBM SPSS statistical 24.0 Version. Descriptive statistics were used to describe the characteristics of the study sample. Data were analyzed using the intention-to-treat (ITT). Last observation values were carried forward to impute the missing data. Shapiro-Wilk test revealed normal distribution for all continuous variables at baseline and follow-ups. Paired sample t-tests were used to examine changes in CHQ-PF50 scores, SDQ scores, and total IPAQ-SF scores in MET-minutes/week at 1 month and 6 months after the intervention. The effect size expressed as Cohen’s d was used to standardize the estimates of outcome changes to allow for comparison between studies.
To explore the association between engagement with the Family Move app and outcomes changes post intervention in children, participants were ranked based on the amount of points earned over the 8-week intervention. Higher rank indicates more frequent views of the coaching videos in the app. After the 8-week intervention, the highest rank was 42 which corresponded to 9650 points. Details of the user ranking can be found in Additional File 3. After creating the participation ranking variable, multiple linear regression analyses were performed with participation ranking as the independent variable and post-intervention outcome changes as the dependent variable, adjusting for child gender, age and baseline outcome level and recruitment month. All regression coefficients were standardized, with p value less than 0.05 indicating statistical significance.