Contributions to the Literature

  • This study will guide future development, implementation and evaluation of FMSs promotion programs among obese children in the long run

  • This study will provide a paradigm of integrating theories and implementation strategies, adding values to future research and practice in health promotion among obese children

  • Research findings will supplement empirical evidence and practical experience for future implementation science on addressing FMSs, healthy lifestyles, and physical and mental health among obese children

  • Research findings will add more understandings of the underlying mechanism of FMSs development, contributing to future theory refinement, intervention design and policymaking

Introduction

Fundamental motor skills (FMSs) are considered the building blocks for more advanced and complicated movements (e.g., games, sports, and recreational activities) that children will develop throughout their lives [1]. FMSs represent a degree of proficiency in a range of motor skills as well as underlying mechanisms such as motor coordination and control [1,2,3]. Commonly developed in childhood and subsequently refined into context- and sport-specific skills, FMSs can be categorized as three aspects: locomotor skills (e.g., running, jumping, and hopping), object control/ball/manipulative skills (e.g., throwing, catching, and dribbling), and stability skills (non-locomotor, e.g., balancing and twisting) [4, 5]. The mastery of FMSs has been purported as crucial elements of children’s physical, social and psychological development, which occurs in an orderly and sequential manner [6, 7]. Good FMSs may be the foundation towards a healthier life because of positive connections with physical activity (PA) [8,9,10], contributing to greater physical fitness [2, 4, 11], body weight status [12, 13], perceived motor competence [10, 14], sports engagement [15], cognitive function [16, 17], perceived well-being [18], and perceived quality of life [19].

Despite the important role of FMSs in children’s holistic development, obese children are usually confronted with an accelerated challenge in developing FMSs [20]. There have been numerous studies indicating that obese children were delayed in FMSs development and showed a prominently poorer performance of FMS tests compared with their peers with healthy weight [21,22,23,24,25]. This may be attributed to multifaceted factors. For example, large body mass index (BMI) can lead to excessive pressure to children’s skeletal system [26] and unfavorable changes in the major brain sites of neuroplasticity [27, 28], and decrease perceived motor capabilities [29], which subsequently inhibit the development of children’s FMSs. For obese children, poor FMSs may also weaken their motivation for engaging in PA and result in a low level of physical fitness, which in turn deteriorates adiposity status and causes a series of negative consequences for other health aspects, e.g., metabolic diseases, and mental disorders among children [30,31,32]. This vicious circle has been clearly illustrated in Stodden et al.’s model [33], which to some extent emphasizes the importance and necessity of promoting FMSs in obese children.

Traditionally, PA intervention programs have shown effectiveness in improving FMSs [32] and other health-related outcomes (e.g., physical fitness, cognition, and mental health) in overweight and obese children [34,35,36]. Schools are considered an ideal setting to implement PA interventions with the aim of promoting FMSs, as children spend most of their waking hours at school and schools can also provide better conditions (e.g., facilities, equipment, curriculum, health experts, peer support), easier access and maximum reach for intervention efforts [37, 38]. However, school-alone settings cannot address the large amount of out-of-school time (e.g., summer holidays) and parental influences that shape children’s behaviors in the home setting [39]. By contrast, family-based PA programs usually focus on the impacts of parents’ support, knowledge, attitudes, motivation, and other psychosocial factors towards children’s behaviors and emphasize the co-activity of parents and children to promote children’s FMSs development [37, 40, 41]. Previous studies have also provided evidence for the effectiveness of family-based PA interventions on improving children’s FMSs and healthy behavioral patterns [40, 41]. Nevertheless, for obese children, the development of FMSs requires more professional instruction and practice guided by qualified experts [3, 42], and this cannot be fully guaranteed in family-alone interventions. In addition, a social cooperative and interactive environment (e.g., at school) can facilitate a better development of FMSs, PA self-efficacy and social skills for obese children [43], while this cannot be fully achieved in a family-alone setting. Taken together, this suggests that a school-family blended PA intervention paradigm which can combine the merits of both school-alone and family-alone approaches, shows great potential in promoting FMSs and related health outcomes among obese children.

Notwithstanding the advocation of school-family integrated PA interventions, empirical evidence on obese children is still scarce, especially in China [44]. In addition, several limitations and research gaps of previous FMSs promotion programs should be further addressed. For example, previous studies show inconsistent findings in the intervention effect on balance among obese children [45, 46], which may be attributed to the lack of specific PA sessions that are tailored to promoting children’s balance in some studies [32]. Furthermore, the findings in terms of the long-term effects of PA interventions on obese children’s FMSs were mixed in previous studies [32]. Some studies indicated a sustained intervention effect of PA intervention on FMSs (e.g., at the 36-week follow-up assessment) [47], while others found that the increase in FMSs of obese children was not maintained during the follow-up, which even relapsed back to baseline levels [48,49,50]. The underlying reasons may be the absence of theory-based targets of interventions and Behavioral Change Techniques (BCT) that play a crucial role in maintaining the PA intervention effects in the long run [51, 52]. Moreover, the mechanisms of why the PA intervention successfully improved obese children’s FMSs have not been systematically examined in previous studies [53]. Identifying the mediation and moderation mechanisms of the intervention program is important and necessary, as it contributes to future design of effective FMSs promotion programs. In addition, previous studies have also shown a series of methodological limitations (e.g., lack of randomization and blinding, lack of objective standardized measures, lack of comprehensive evaluations for the intervention fidelity and quality) [32, 53], which may weaken the future implementation and generalization of the study findings.

To address the research and practice gaps, the present study aims to develop, implement, and evaluate a 24-week school-family blended multi-component PA intervention program for promoting FMSs and health among Chinese obese children, namely Fundamental Motor Skills Promotion Program for Obese Children (FMSPPOC). The particular objectives of outcome evaluation include: (1) examine the intervention effects of the FMSPPOC on improving the primary outcome (i.e., FMSs) among Chinese obese children; (2) examine the intervention effects of the FMSPPOC on improving the secondary outcomes (health behaviors, physical fitness, perceived motor competence, perceived well-being, M-PAC components, anthropometric and body composition measures) among Chinese obese children; and (3) identify the interrelationships between FMSs and physical and psychological outcomes (i.e., mediation mechanisms) and the moderating role of demographics.

Method

Study design

This study will apply a two-group double-blinded cluster randomized controlled trial (CRCT) with four measurement occasions, including baseline assessment (T0), mid-intervention assessment (T1: 12 weeks after the baseline assessment), post-intervention assessment (T2: 24 weeks after the baseline assessment), and follow-up assessment (T3: 48 weeks after the baseline assessment). Two groups include: 1) an intervention group (IG), receiving the FMSPPOC intervention for 24 weeks; and 2) a waiting-list control group (WCG), receiving the FMSPPOC intervention or relevant materials (based on participants’ requirements) after the completion of all data collection for IG (see Fig. 1). The design, implementation, and reporting of the FMSPPOC will follow the SPIRIT guidelines and the CONSORT statement [54, 55] (Supplement Material 1). The study protocol was approved by the Research Ethics Committee of Hebei Normal University (ref. No.2021LLSC051). This study was a key part of a large research project funded by the National Social Sciences Funding Committee of China (Ref. No.: 19200526).

Fig. 1
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CONSORT flow diagram

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Participants

As childhood is a critical period for developing favorable FMSs that can continuously affect health and individual development in adolescence and adulthood, a health-promoting intervention that targets this age group is vitally important [56]. In pre-adolescence, neuroplasticity may be greater, changes faster based on experience [57, 58] and the brain may be particularly sensitive to the effects of PA when the brain's neural circuits are still developing [59]. Therefore, to address age-related declines in PA and maximize the benefits of PA on FMSs, obese children aged 8 to 12 years were selected as the target population for this study with obesity defined as a body mass index (BMI) at or above the 95th percentile of the sex-specific BMI-for-age growth charts (https://www.cdc.gov/obesity/data/childhood.html).

Sample size estimate

An average medium effect size (Cohen d = 0.54) of PA intervention on FMSs in obese children was proposed based on previous studies [32]. Considering the minimal class size is 30 and the prevalence rate of childhood obesity is approximately 20% [60], a cluster size of 6 (for each class) was selected in this study. Using an ICC of 0.01 [61], an alpha of 0.05, a statistic power of 80%, and an attrition rate of 15% [43], at least 84 participants in each condition (12 clusters per condition), for a total of 168 participants in 24 clusters will be required for this CRCT.

Recruitment and eligibility criteria

Based on the sample size estimate, this study is intended to recruit 24 classes from six primary schools (grades 2–5), excluding the private or special education schools or those participating in other PA-related programs. Using a random stratified sampling approach (e.g., socioeconomic status, geographical location, grade and class size of each school), six primary schools will be recruited in Shijiazhuang, Hebei, China. An invitation letter describing the study nature and participation requirement will be delivered to the principals of eligible schools. Upon the approval of the principals, one class from each grade will be randomly selected to participate in this study. All children in the selected classes will be provided with an informed pack comprising a plain language statement and a written informed consent form to be signed by their parents. The eligibility criteria will include: (1) aged 8–12 years; (2) Body Mass Index (BMI) greater than Chinese obesity cutoffs corresponding to 95th percentile of sex-specific and age-specific BMI reference standards [62]; (3) no previous substantial experiences in participating in FMSs-related promotion programs; (4) no prior diagnosis of physical, verbal, and cognitive disorders that may prevent participation in PA program and interrupt the outcome evaluation.

Randomization and blinding

To avoid the potential for contamination, randomization will be conducted at the school level. All eligible schools will be randomly assigned to one of the two groups prior to baseline assessment, where each group will consist of three schools. Each school will select 28 obese children from four classes covering grades 2–5 to participate in this study, and the children in the same school will receive the same treatment. Randomization will be implemented with a ratio of 1:1, using the Excel software by a researcher who will not be involved in the participant recruitment, data collection or evaluation. Due the ethical concerns, participants are not able to be blinded as they will be informed with the study purpose and group allocation in the written informed consent form. Intervention facilitators and outcome evaluators will be concealed for the group allocation.

Fundamental motor skills Promotion Program for Obese Children (FMSPPOC)

FMSPPOC is a school-family blended multi-component intervention program, which aims to promote the development of obese children’s FMSs in a supportive environment, providing the children with both positive experiences (e.g., enjoyment, success, and accomplishment) in relation to PA, and cultivate interest in sports, so as to enhance their PA level/engagement, perceived motor competence, fitness and wellbeing in future. The FMSPPOC will last 24 weeks, consisting of two parts: a 12-week initiation phase, and a 12-week maintenance phase.

Theoretical backdrop: multi-process action control model

To enhance the effectiveness and implementation of the intervention, the Multi-Process Action Control model (M-PAC) will be used as the theoretical backdrop [63]. The M-PAC model postulates that individuals’ behavioral change is a continued process from intention formation to behavioral initiation and maintenance, consisting of reflective, regulatory, and reflexive processes [64]. In the M-PAC framework, intention is conceived as a decisional construct (i.e., has intention/ has no intention). Similar with the tenets of other psychosocial theories (e.g., the Theory of Planned Behavior, TBP; Capability, Opportunity, Motivation, Behavior model, COM-B), the M-PAC emphasizes the influence of several determinants of intention which function in the reflective processes (i.e., consciously deliberated and expected consequences of performing a behavior) [65]. Particularly, instrumental attitude (e.g., PA is useful), affective attitude (e.g., PA is enjoyable), perceived capability (e.g., I have the ability to perform a behavior), and perceived opportunity (e.g., I have the time and can access to perform PA) play a crucial role in forming a behavioral intention [66]. Furthermore, the M-PAC framework proposes that whether a behavioral intention can be successfully translated to an actual behavior is determined by the reflective processes of affective attitude and perceived opportunity as well as the enactment of regulation processes. Particularly, higher levels of affective attitude and perceived opportunity are considered necessary for successful translation of behavioral intention into actual behavior than for intention formation. Similar with the Health Action Process Approach (HAPA), the M-PAC framework also suggests the importance of regulatory strategies (e.g., action planning and coping planning) in the intention-behavior translation [67]. In addition, extending on previous psychosocial theories, the M-PAC framework highlights the important role of diverse impulsive components in behavioral maintenance (i.e., “continuance of actional control is thought to rely upon the development of reflexive processes”) [68]. It suggests that impulsive components affect actional control most often through learned associations and are triggered through specific circumstances/cues and stimuli [69]. The M-PAC framework emphasizes the development of two crucial reflexive processes, including habit (e.g., I will engage in PA automatically) and identity (e.g., I am a person who is physically active), as individuals begin to perform the behavior more regularly [63,64,65]. Therefore, a developed behavioral pattern of action control will be determined by the independent influence of relative, regulatory, and reflexive processes [63,64,65]. Targeting the psychosocial components of the M-PAC model, a series of Behavioral Change Techniques (BCTs) will be also adopted [70, 71] in the FMSPPOC program (see Table 1).

Table 1 M-PAC components and behavioral change techniques involved in the FMSPPOC
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12-week initiation phase

During the first 12-week initiation phase, the intervention consists of school-based PA sessions and family-based PA assignments for the whole classes including the obese children to prevent stigmatization or exclusion. Particularly, the school-based PA sessions will be delivered twice a week (90 min each session) for 12 weeks (totally 24 sessions). Three ball games (i.e., soccer, basketball, and volleyball) will be used as the main content of school-based PA sessions for FMSs promotion due to the consideration of effectiveness, enjoyment, feasibility, and greater adherence [72, 73]. Each session will include a 5-min warm-up, a 15-min physical fitness training, a 60-min FMSs training (30-min learning and practice + 30-min game), and a 10-min cool-down. For the FMSs training part, three types of ball games will be delivered in different weeks, including week 1–4 for soccer, week 5–8 for basketball, and week 9–12 for volleyball. Each ball game section will include skill instruction and learning, skill practice (guided by teachers + self), game part, and review/summary. All the movements in each section will be designed to achieve a moderate-to-vigorous intensity. Detailed content of the school-based PA sessions can be found in Table 2.

Table 2 The content of the school-based PA sessions
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In addition to school-based PA training, all the participants are asked to complete a 30-min family-based PA assignment at least three times per week during the first 12-week initiation phase. The purpose of the family-based PA assignment is to reinforce FMSs practice and promote PA engagement during the out-of-school time. For each PA assignment, participants are asked to complete several activities together with their parents (i.e., parent–child co-activity). These activities are modified from the school-based PA sessions that can be easily undertaken in a family-setting (e.g., require minimal equipment, can be undertaken indoors or outdoors within limited space). Parents will also be asked to track their child/children’s weekly completion times and conditions and upload this information to a designated column of the Ding-Talk APP (https://www.dingtalk.com/en, Alibaba Group). At weekends, the research team members will check the participants’ PA assignments and reward them with small red flower stickers as incentives: participants who complete PA assignments three times will receive one sticker while who complete the assignments five times or more will receive two stickers. The greater number of red flowers participants accumulates, the more prizes (e.g., sports bracelets, suits, and sneakers) they can redeem at the end of the intervention.

12-week maintenance phase

12-week maintenance phase will be implemented mainly during the summer holidays following the 12-week initial phase. This part will consist of three face-to-face workshops with three online webinars (using Ding-Talk APP) only for the target population of obese children. The offline workshops and online webinars will be conducted alternatively and biweekly. Each workshop and webinar will last for 60 min, consisting of 30-min expert talk, 20-min interactive activity, and 10-min Q&A. The main purposes of the offline workshops and online webinars will include: (1) maintaining children’s FMSs practice; (2) promoting healthy lifestyles (e.g., regular engagement of PA, limited sedentary time, high quality sleep, balanced diet) in the long run; (3) addressing existing problems and future challenges. The topics will include (1) practicing FMSs in daily life (e.g., FMSs games introduction, tips of FMSs practice); (2) PA and health (e.g., recommendation of PA for children, co-activities of parent and child); (3) sedentary behavior and health (e.g., recommendation of screen time, tips of interrupting prolonged sitting); (4) good sleep (e.g., sleep recommendation in terms of the duration and quality); (5) eating happily and healthily (e.g., healthy food selection, healthy cooking, and “say no to snacks”); (6) existing problems and future challenges in children’s FMSs (e.g., existing problems in daily practice of FMSs, how to maintain the development of FMSs after the project completion).

Procedure and quality control

The FMSPPOC development will be facilitated through five steps. Step 1 is to form a steering group, consisting of relevant stakeholders (e.g., research team members, PA instructors, primary school managers, and obese children and their parents). In Step 2, the research group will develop the intervention content and practical strategies. In the 3rd step of program production, all the stakeholders will discuss on consensus with respect to the refining and confirming of the intervention content and practical strategies, and then a two-month pilot study will be conducted to test and optimize the strategies and relevant materials. Participant recruitment and maintenance, data collection instrument and schedule, adaptability and feasibility of the intervention will be fully considered in the pilot study. In Step 4, a comprehensive plan for the intervention implementation will be constructed. To ensure the safety, supportiveness, enjoyment, and efficiency of the intervention during the implementation. An operational manual and training materials will be developed in this step. In Step 5, a plan to evaluate the implementation and effectiveness of the intervention will be developed. Any amendments will be made if necessary (Fig. 2).

Fig. 2
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Gantt chart of research activities

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For the project implementation, two 60-min face-to-face briefing sessions will be first provided for the intervention facilitators (i.e., PE teachers, student helpers, parents) one month prior to the FMSPPOC commencement (delivered by the investigators and/or research assistant) in the university gymnasium. One briefing session will focus on necessary knowledge and skills training so that PE teachers and student helpers can implement the intervention plan smoothly and effectively. In addition, the implementation details, rationale, nature, and benefits of FMSPPOC will be introduced. Another briefing session will train all evaluators on the measurement of FMSs, health behaviors, and physical fitness, as well as the specification of psychological measures.

For the main study, the school-based PA sessions will be conducted in an indoor playground at a primary school during afternoon custody time (4:00–5:00 p.m.) by qualified PE teachers with assistance of student helpers. The attendance of participants will be also recorded. In addition, to monitor the PA intensity, three mid-tests will be conducted using downloadable, wireless Polar Team Pro (Polar Team Pro, Kempele, Finland) and Polar heart rate sensor during the ball games (week 3, 7, & 11).

For the family-based PA assignments, relevant tasks and instructions will be introduced for parents in the beginning briefing session. The research assistants will remind parents to upload the required information each week via SMS messages and deliver the incentives correspondingly. For the second 12-week maintenance phase, the offline workshops will be implemented at a multi-function sports room in a primary school, while the online webinars will be conducted using Ding-Talk APP. These workshops and webinars will be facilitated by trained PE teachers and health experts from Hebei Normal University. Each participant will be asked to attend the workshops and webinars with at least one parent or legal guardian.

Implementation evaluation

This study will use the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework [74, 75] to assess the implementation of FMSPPOC among obese children. Details can be found in Table 3.

Table 3 The RE-AIM framework of implementation evaluation for the FMSPPOC program
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Outcome evaluation

A description of the measurements in the present study are presented in Table 4. All the measurements will be conducted on four occasions, including baseline assessment (T0), mid-intervention assessment (T1: 12 weeks after the baseline assessment), post-intervention assessment (T2: 24 weeks after the baseline assessment), and follow-up assessment (T3: 6-month after the intervention completion).

Table 4 Description of the outcome measures
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In addition, the collection of all indicators at the four-time points will follow the following process. Day 1–7: Demographic information (filled by parents) and ActiGraph 3X + measured PA, sedentary behavior, and sleep; Day 8: anthropometric and body composition measures and FMSs; Day 9: physical fitness assessment; and Day 10: psychological outcomes. The Day 8–10 data collection will be implemented by four trained student helpers with assistance of PE teachers in an elementary school gymnasium, where the temperature will be constant at 20℃ and humidity will be controlled at 50% during the assessment.

Data analysis

Quantitative data analyses will be performed using SPSS and Mplus. Descriptive statistics of all continuous variables will be expressed as mean ± standard deviation (M ± SD). Independent samples t-tests and Chi-square tests will be employed for checking the randomization, analyzing the dropout, and detecting the potential confounders at baseline. Intention-to-treat approach will be used for the primary analyses, with per-protocol analyses as sensitivity tests. Missing data will be imputed using a multiple imputation approach with linear and logistic regression equations. The statistical significance level will be set to p < 0.05 (two-tailed). Generalized linear mixed models (GLMM) will be used to evaluate the intervention effects on outcome measures, with time, condition, and the interaction of time and condition as fixed effects, adjusting for baseline values. Post-hoc tests will be conducted where a significant interaction effect is detected by using the least significant difference method. In addition, structural equation modeling will be used to analyze the interrelationship (e.g., mediation mechanisms) of outcomes, using a bias-corrected bootstrap approach (5000 resamples). For the qualitative data, a thematic analysis approach will be applied using NVivo 11 software.

Discussion

Obesity is becoming an increasing problem also in China and Chinese children, but rather little evidence is available how to address this. There are indicators, that this trend is similar to those in other countries. In 2008, Stodden et al. [33] proposed a “conceptual model of children's motor development” based on partial evidence and experience, which hypothesized the relationship between FMSs and multiple health indicators (e.g., PA, perceived motor competence, physical fitness, and weight status) of children. The authors point out that FMSs levels may positively or negatively affect PA and weight status in children, and that healthy or unhealthy weight status may also promote or restrict the development of FMSs in children over time, with perceived motor competence and physical fitness mediating the relationship between FMSs and PA [33]. In recent years, overweight and obese children have been consistently reported as scoring significantly lower than their healthy weight counterparts on FMSs, suggesting that poor FMSs can contribute to overweight/obesity [21,22,23,24,25, 94]. Similarly, obesity may likewise act as a constraint on FMS development and proficiency, generating biomechanical changes and adjustments in movement [94]. In previous studies, FMSs have been shown to correlate with PA in school-aged children [4], and strong positive associations have been observed between FMS proficiency in children at age 6 and leisure time PA in adults at age 26 [95]. Further to regular PA participation, additional health benefits of FMSs proficiency have been associated with increased cardiorespiratory fitness [96] and perceived motor competence [10, 14], as well as reduced overweight and obesity [12, 13]. This indicates the importance of effective interventions being implemented to allow overweight/obese children to develop their FMS early, reducing their risk of obesity through continued PA into adolescence and adulthood.

To our knowledge, FMSPPOC is the first school-family blended multi-component FMS-promotion program to be designed in China, which makes up the research and practical gaps as suggested in previous studies and shows a series of strengths: 1) standard methods will be applied for assessment of FMSs; 2) the use of theoretical framework and behavioral change techniques will ensure the implementation and effectiveness of the FMSs promotion program; 3) the gold standard for scientific designs (i.e., CRCT) will be applied and comprehensive measures will be implemented, which can contribute to a robust examination of the program effectiveness and a better understanding of the potential mechanisms; 4) the use of the RE-AIM framework will enhance the quality of the program and enable us to evaluate the implications of FMSPPOC among obese children broadly. We anticipate that FMSPPOC will also be a new paradigm of secondary obesity prevention. In addition, we will propose and assist health and education governments to advocate and disseminate the blended intervention among all primary schools to tackle unhealthy lifestyles in children and further improve health status of obese children in China. Other countries and regions with similar demographics to China can also learn and benefit from this product. Surely, comparisons to other cultures need to follow up and mechanisms are required to be evaluated, too. With that, the research of this study and comparable one can inform not only research and practice but also theory refinement and scaling up approaches.