Barriers and Facilitators of Physical Activity Participation among Children and Adolescents with Intellectual Disabilities: A Scoping Review

Background: Children and adolescents with intellectual disabilities (ID) have low levels of physical activity (PA). Understanding factors influencing the PA participation of this population is essential to the design of effective interventions. The purposes of this study were to identify and map the barriers and facilitators of PA participation among children and adolescents with ID. Methods: A scoping review was conducted in accordance with established methodology. Articles were evaluated for relevance using predetermined inclusion criteria in eight databases. Extracted barriers and facilitators were classified using the social ecological model as individual, interpersonal, or environmental factors. Results: Thirty-two studies published between 1992 and 2020 were included (24 quantitative, 6 qualitative, and 2 mixed-method). Thirty-four factors were identified. The most commonly reported barriers included disability-specific factors, low self-efficacy, lack of parental support, inadequate or inaccessible facilities, and lack of appropriate programs. The most commonly reported facilitators included high self-efficacy, enjoyment of PA, sufficient parental support, social interaction with peers, attending school physical education (PE) classes, and adapted PA programs. Conclusions: Continued exploration of factors influencing PA participation is required among children and adolescents with ID. Future interventions should involve families, schools, and wider support network in promoting their PA participation together.


Introduction
Physical activity (PA) is defined as any bodily movement produced by skeletal muscles that requires energy expenditure [1] and is characterized by its modality, frequency, intensity, duration, and context of practice [2]. PA promotes numerous physical and mental health benefits in children, including children and adolescents with disabilities [3][4][5]. Regular and adequate levels of PA can improve children's cardiorespiratory and muscular fitness, bone health, and cardiovascular and metabolic health biomarkers, reduce symptoms of anxiety and depression, and help to maintain a healthy weight [6]. Despite the physiological and psychological health benefits associated with PA participation, previous studies reported that children with intellectual disabilities (ID) did not meet the PA guideline of at least 60 min of moderate-to-vigorous-intensity physical activity (MVPA) per day [7][8][9]. In addition, children and adolescents with ID are less active than their counterparts without disabilities [10,11].
ID is characterized by significant limitations in intellectual functioning and adaptive behavior, which covers many everyday social and practical skills and originates before the age of 18 years [12]. Children and adolescents with ID tend to have greater sedentary behaviors because associated physical, sensory, and/or cognitive impairments place them

Methods
This study adopted an established six-stage scoping review protocol proposed by Arksey and O'Malley [21] and further refined by Levac et al. [24] and followed the Preferred Reporting Items for Systematic Review and Meta-Analysis Extension for Scoping Reviews (PRISMA-ScR) statement [25]. The study protocol was registered with the Open Science Framework (https://osf.io/kp5cd (accessed on 20 November 2021)).

Stage 1: Identify the Research Question
The primary question to be addressed through this scoping review was "What are the barriers to PA and facilitators of PA participation among children and adolescents with ID?"

Stage 2: Identify Relevant Studies
A comprehensive search was performed using eight electronic databases: Web of Science (WOS), Academic Search Premier (ASP), MEDLINE, Education Source (ES), Education Resource Information Center (ERIC), PsycINFO, Psychology and Behavioral Sciences Collection, and Scopus. The search gave access to a range of health, sport, psychology, medicine, and education journals. A list of keywords and alternative keywords were created, combined using Boolean operators ("AND", "OR"), and included in the aforementioned search databases. The English search strings included: 1.
Correlate * OR factor * OR reason * OR predictor * OR barrier * OR facilitator * Articles published between 1950 and 2020 were eligible for review. All articles were published in English and available in full-text format. Hand searching and snowballing techniques from the reference lists of systematic reviews and key references were performed to identify potentially relevant studies not captured by database searches [26].

Stage 3: Study Selection
The inclusion criteria were as follows: (1) empirical research (qualitative and quantitative) that focused on identifying barriers and facilitators related to PA among children and adolescents with ID. All reported dimensions of PA were eligible for inclusion, for example, mode, frequency, duration, and intensity of PA [27]. PA intensities are categorized as follows: light PA (LPA: 1.6-2.9 metabolic equivalents of task (METs)), moderate PA (MPA: 3.0-5.9 METs), vigorous PA (VPA: ≥6.0 METs), and MVPA (≥3.0 METs) [27]; (2) the study participants included were children and adolescents with ID (age range 5-17 years) or parents and/or caregivers giving information regarding their children with ID; (3) full-text publication in English; and (4) published in a peer-reviewed journal before 31 December 2020.
The exclusion criteria were as follows: (1) studies in which PA and its barriers or facilitators were not the main outcome. (2) more than 50% of the participating children did not have ID, and the results were not presented separately; (3) studies were not empirical (e.g., conceptual, review, or philosophical only), and (4) editorials without extensive references, dissertations, theses, conference proceedings, and abstracts. This review included only original, peer-reviewed published articles and did not include any grey literature due to limited time and resource and language barriers.
All references were exported to EndNote Online, and duplicates were identified and removed through the software and manual review of the citation list. Articles were assessed for eligibility by title and abstract first, according to the inclusion criteria. Full-text articles were obtained where studies met criteria or could not be excluded on the basis of title and abstract alone. The identified studies were determined by four reviewers (S.-Y.Y., T.-J.W., T.-W.Z., and Y.-T.Q.) independently according to the inclusion and exclusion criteria. A fifth reviewer (J.Q.) was consulted in case of disagreement. Eligible studies were those that reported barriers and/or facilitators of engaging in PA using quantitative, qualitative, or mixed methods.

Stage 4: Charting the Data
Data were extracted and presented according to the methodology of the included studies. The identifiers and variables included first author and year of publication, type of study, geographic location, sampling strategy, participant details (i.e., sample size, age, gender, and ID level), theory, research design, measures, and dimensions of PA.

Stage 5: Collating, Summarizing, and Reporting Results
The data collected from the identified studies were inputted into a table and were analyzed descriptively. The social ecological model is a framework that aims to understand multiple levels of influence on specific health behaviors, including intrapersonal (individual), interpersonal, organizational, community, physical environmental, and policy [28]. This model leads to the explicit consideration of multiple levels of influence that broadens options for interventions [28]. Previous research [29][30][31] also demonstrated that this framework is useful in trying to understand facilitators and barriers influencing PA behavior in vulnerable populations. Thus, it was used as the theoretical framework for helping categorize factors and interpret our findings. Aligned with the guidelines of a scoping review, none of the studies were evaluated for quality and all works reported in this review were based on direct presentation of results from the authors of the included studies [21].

Stage 6: Consulting with the Experts
We aimed to enhance the methodological rigor of this review through expert consultation to gain additional sources of information and perspectives [21,24]. Several researchers (professional stakeholders) with expertise in PA participation of children and adolescents were involved throughout this review process. The experts were invited to review and offer suggestions for the searching strategies. According to the results of expert consultation, we optimized the key terms (i.e., added terms "physical education" and "young athlete *", changed term "sport activit *" to "sport *"), and refined the inclusion and exclusion criteria of studies (e.g., identified specific types of studies or articles to exclude). Following the search and summary of the literature, the experts also provided perspectives on our thematic synthesis to help us finalize the themes and interpret of the findings.

Searching Results
The initial search identified 1876 studies (WOS, n = 761; ASP, n = 5; MEDLINE, n = 507; ES, n = 5; ERIC, n = 3; PsycINFO, n = 109; Psychology and Behavioral Sciences Collection, n = 1; Scopus, n = 485). Thirty-three additional studies were identified through related reviews. After removing duplicates from the original sample (n = 1909), title and abstract screening of 1301 articles was performed, from which 1228 studies were excluded. The researchers read the full text of the remaining 73 articles and excluded another 41. Finally, 32 studies were included in this review. Figure 1, adapted from the PRISMA group [32], displays the detailed search and study selection process.
scoping review, none of the studies were evaluated for quality and all works reported this review were based on direct presentation of results from the authors of the includ studies [21].

Stage 6: Consulting with the Experts
We aimed to enhance the methodological rigor of this review through expert cons tation to gain additional sources of information and perspectives [21,24]. Several resear ers (professional stakeholders) with expertise in PA participation of children and ado cents were involved throughout this review process. The experts were invited to revi and offer suggestions for the searching strategies. According to the results of expert c sultation, we optimized the key terms (i.e., added terms "physical education" and "you athlete *", changed term "sport activit *" to "sport *"), and refined the inclusion and clusion criteria of studies (e.g., identified specific types of studies or articles to exclud Following the search and summary of the literature, the experts also provided persp tives on our thematic synthesis to help us finalize the themes and interpret of the findin

Searching Results
The initial search identified 1876 studies (WOS, n = 761; ASP, n = 5; MEDLINE, 507; ES, n = 5; ERIC, n = 3; PsycINFO, n = 109; Psychology and Behavioral Sciences Col tion, n = 1; Scopus, n = 485). Thirty-three additional studies were identified through rela reviews. After removing duplicates from the original sample (n = 1909), title and abstr screening of 1301 articles was performed, from which 1228 studies were excluded. T researchers read the full text of the remaining 73 articles and excluded another 41. Fina 32 studies were included in this review. Figure 1, adapted from the PRISMA group [3 displays the detailed search and study selection process.  Table 1 summarizes the details of the studies that met the inclusion criteria. The final 32 articles selected for review were published between 1992 and 2020, 24 of which (75%) were published after 2010. These studies we conducted in the USA (12), UK (5), Canada (3), China (3), Australia (2), Iceland (1), Italy (1), the Netherlands (1), the Philippines (1), Saudi Arabia (1), Spain (1), and Trinidad and Tobago (1). A total of 24 studies employed quantitative methods of data collection, 6 used qualitative data collection methods, and the 2 remaining studies adopted mixed methods. Of the quantitative and mixed-method studies, 18 articles employed a cross-sectional design, 6 adopted intervention, one used a longitudinal design, and one utilized a case design. The six qualitative studies all employed a phenomenological design. Of the quantitative studies, 17 studies used objective measures including accelerometers (n = 11), pedometers (n = 3), heart rate monitors (n = 4), and quantitative observation (n = 6) to quantify PA. Nine studies used questionnaires as subjective measures. Two of the quantitative studies utilized more than one measurement tool. The intensity and duration of PA were presented as different ways due to different measurements. Among included quantitative studies, 17 studies used different PA dimensions including LPA, MPA, MVPA, and number of steps per day. Another 9 studies used regular PA, PA frequency, and PA perceptual characteristics based on subjective PA questionnaires. The qualitative studies used interviews (n = 4) and focus groups (n = 2) to explore the barriers and facilitators to PA among children and adolescents with ID. The mixed-method studies involved objective (e.g., accelerometers, quantitative observation, heart rate monitors) and subjective measurements (e.g., questionnaire, interviews). These two studies used different dimensions including MPA and MVPA. Of the 32 studies, 15 studies used a purposive sampling strategy, 10 studies used a convenience sampling strategy, and 7 studies did not provide an indication of the sampling strategy. The sample size ranged from 3 to 535, including one with more than 500 participants, 4 with 100 to 500 participants, 16 with 30 to 100 participants, and 11 with less than 30 participants. In all, 6 (19%) stated the use of theories, including social cognitive theory (n = 2), self-determination theory (n = 2), occupational perspective theory (n = 1), and dynamic systems theory (n = 1).

Thematic Synthesis
The barriers and facilitators of PA participation among children and adolescents with ID are classified into three groups of studies using different research methods. Specifically, barriers and facilitators are presented under individual, interpersonal, and environmental levels of influence based on the social ecological model [28] (Table 2).

Barriers to Participating in PA Qualitative Studies
The included qualitative studies identified barriers to PA participation among children and adolescents with ID based on the perceptions of parents, teachers, and adolescents with ID. Any dimension of PA was not available in these studies. At the individual level, the results of studies showed that conditions associated with ID, such as developmental delays [57], ear problems [49], and common characteristics associated with DS (including hypotonia, congenital heart defects, and communication impairments) [51] were identified as physiological factors that inhibited PA participation in children and adolescents with ID. Low self-efficacy [38] and lack of understanding on the importance of PA and its benefits for health [48] were identified as cognitive and psychological barriers to PA participation. Interpersonal factors are related to interpersonal processes and primary groups, such as family and peers [63], influencing PA participation among children and adolescents with ID. Lack of parental support (including lack of parents' company [46,51], lack of family's financial support [46,57], lack of transport support [49], lack of information for parents on how to conduct home-based activities [57]), and parent's vigilance and overprotection [46,51] were identified as family barriers to PA participation among children and adolescents with ID. In addition, lack of social networks (e.g., lack of social connectedness with others) was also identified as an interpersonal barrier to PA participation among children and adolescents with ID [38]. At the environmental level, inadequate or inaccessible facilities [46] and lack of appropriate programs [51,57] were identified as social environmental barriers to PA participation among children and adolescents with ID. Poor weather, as one of the natural factors, prevented this population from participating in outdoor activity and thus decreased their PA [38,46].

Quantitative Studies
At the individual level, low motor development (e.g., low locomotor and object control skills) [9,33,45] was identified as a barrier that influenced MVPA or the number of steps per day among children and adolescents with ID. Low self-efficacy [43] and a preference for indoor activities [62] were identified as cognitive and psychological barriers that influenced regular PA and rating perceived exertion of PA participation among children and adolescents with ID. At the interpersonal level, lack of a social network (e.g., have fewer friends) was identified as a barrier that influenced regular PA among children and adolescents with ID [43]. At the environmental level, teacher and classroom-related factors were examined in previous studies. The results of the study found that lesson contexts organized by PE teachers (e.g., allocating the substantial amount of lesson time for management) and teaching behaviors (e.g., spending considerably more time transmitting physical education (PE) knowledge), which reduced opportunities for students to participate in MVPA, were identified as barriers [56].

Mixed-Method Studies
Lack of parental support [59] and lack of public transportation [59] were, respectively, identified as barriers at the interpersonal and environmental levels that influence MPA among children and adolescents with ID in one study using mixed methods.

Facilitators of Participating in PA Qualitative Studies
Facilitators of PA participation among children and adolescents with ID reported by the included qualitative studies were also identified from perceptions of parents, teachers, and adolescents with ID. At the individual level, physical skills were identified as facilitators of participating in PA among children and adolescents with ID [51]. Cognitive and psychological factors, such as high self-efficacy [38], enjoyment of PA [48,49], and personality traits (e.g., enthusiastic and determined) [51] were also facilitators. At the interpersonal level, sufficient parental support (e.g., parents' positive role model, parental company and logistic supports) [38,48,49,51,57], positive role of siblings [51,57], and positive social interactions with peers [38,49,51,57] were identified as facilitators of participating in PA among children and adolescents with ID. At the environmental level, PA programs available in the community adapted for children and adolescents with ID were identified as social environment facilitators of participating in PA among children and adolescents with ID [51]. Attending PE classes [38], teaching methods, and a strong home-school link [48] were identified as school environment factors of participating in PA among children and adolescents with ID.

Quantitative Studies
At the individual level, physical skills (e.g., riding a bicycle) were identified as physical ability factors that influence MVPA among children and adolescents with ID [53]. Wanting to lose weight [40], high self-efficacy [43], and enjoyment of PA [43,44] were identified as cognitive and psychological facilitators that influence PA frequency, regular PA, LPA, and MPA among children and adolescents with ID. In addition, caregiver's higher educational level was another individual facilitator that influenced regular PA among children and adolescents with ID [54]. At the interpersonal level, sufficient parental support (e.g., parents' company) [37] and positive parental beliefs of the benefits of PA for their child [41] were identified as family factors that influence PA frequency among children and adolescents with ID. In addition, positive social interactions with peers [11,52] and positive relationships with the coach [37] were identified as social network facilitators that influence PA frequency among children and adolescents with ID. At the environmental level, an exergaming context implemented at home or at school was identified as a facilitator that influenced MVPA among children and adolescents with ID [34]. Adequacy and availability of environmental resources (e.g., access to transportation) were identified as social environment factors that influenced PA frequency among children and adolescents with ID [37]. PA programs available in the community adapted for children and adolescents with ID were also identified as facilitators that influenced LPA and MVPA among children and adolescents with ID [50,53]. In terms of school factors, attending PE classes and participating in physical activities during school recess [40,42,45,47,55,58,60,61] were identified as key facilitators that influenced MVPA or number of steps per day among children and adolescents with ID. Inclusive PE programs (e.g., a peer-tutored PE program) [35] were also identified as school facilitators that influenced the LPA and PA frequency of children and adolescents with ID. In addition, high autonomy-supportive instructional climates [36] and PE lesson contexts focused on skill practice [56] were identified as facilitators that influenced MVPA among children and adolescents with ID.

Mixed-Method Studies
An adapted PA program using group video conferencing for the promotion of PA [39] was identified as a facilitator that influenced MVPA among children and adolescents with ID at the environmental level.

Discussion
This scoping review provided an overview of the barriers and facilitators to PA participation among children and adolescents with ID. A systematic search yielded 32 studies published between 1992 and 2020. Research has steadily increased in this area over the last few years, which showed that scholars have paid increasing attention in the PA of children and adolescents with ID in the past decade. Among the included studies, quantitative studies are the most numerous. Most of these studies had problems related to the cross-sectional design and the sample (e.g., small sample size). The cross-sectional research design cannot indicate causality. The results cannot be generalized because of the relatively small sample size. Thus, more longitudinal studies are needed to identify factors that have causal associations with PA [64]. Further studies in larger samples are also necessary to improve the study quality and generalizability of findings [65]. There was a dearth of experimental studies using random assignment or that were well-controlled investigations with contrasting groups or conditions. Randomized control trials/quasiexperimental studies are useful to establish the efficacy of interventions targeting barriers to PA, which is important and necessary for effectively promoting PA participation among children and adolescents with ID [65,66]. Studies using this design must address quality control in design and reporting to ensure the usability of findings [67].
The results of the quantitative and mixed-method studies included in this review showed that different barriers and facilitators could influence different dimensions of PA in children and adolescents with ID. However, the evidence available based on these studies was limited and incomplete. It would therefore be a research direction to comprehensively examine the relationships between barriers or facilitators and various dimensions of PA (e.g., different intensities, frequencies, and modes) in this ID groups.
Qualitative studies help to explore and understand full-breadth issues in relation to the PA participation experienced by a specific population [23]. Therefore, it would be best suited to the profound exploration of the specific barriers and facilitators of PA participation among children and adolescents with ID [68]. However, only 19% (n = 6) of the studies included in this review employed a qualitative research design. Qualitative studies are needed to address how children and adolescents with ID participate in PA and why their PA levels are lower than their peers without disabilities [47,69]. Theoretical frameworks were designed to help comprehensively understand the relationship between factors and the mechanisms by which they affect behavior [22]. However, only 19% (n = 6) of the research used a theoretical framework to guide their studies. Studies using the behavioral theoretical frameworks are urgently needed to better understand healthy behavioral patterns and guide the development of effective interventions to promote PA among children and adolescents with ID [22,66].
Based on the social ecological model, our synthesis of the studies identified 34 factors primarily related to individual, interpersonal, and environmental elements at several levels of influence. The most predominant barriers identified in this review at the individual level were disability-specific factors, including conditions associated with ID (e.g., developmental delays, ear problems, communication impairments) and low motor development. This finding is consistent with previous reviews on examining parental perceptions of facilitators and barriers to PA for children with ID [70]. Children's conditions associated with ID may decrease the activity levels because of their influence on body structure and function [51]. This finding suggests a need for greater emphasis on home-and communitybased programs that promote health wellness issues for this population to help understand the physical limitations that they may present, make appropriate adaptations to PA, and provide them with opportunities for PA participation [46,57]. The low motor development of children and adolescents with ID relates to their generally slow developing of basic physical skills required to be active, and increased motor development has been identified as an underlying mechanism to promote PA participation [9,19,71]. Thus, consideration of how to improve the physical fitness and motor skills of children and adolescents with ID may have a long-term influence on the amount of PA they undertake. Previous studies confirmed that motor skill interventions had positive effects on improving the motor development of children and adolescents with ID [72,73]. Therefore, professionals are recommended to develop more effective motor skill interventions, such as developmental physical education programs, therapeutic sensorimotor training, or intensive motor skill training, to increase their motor development [74].
Self-efficacy was the second most frequently reported factor influencing the PA participation of children and adolescents with ID at the individual level. High self-efficacy can increase the intrinsic motivation to participate in PA among children and adolescents with ID, whilst low self-efficacy thwarted intrinsic motivation, highlighting the importance of considering their self-efficacy in activities when attempting to encourage PA in this population [38]. Parents, PE teachers, and researchers should be aware that the activities must be tailored to the individual in relation to their self-efficacy and provide social support in activities to increase their self-efficacy to maintain interest and enjoyment, instead of just promoting activities. In addition, the perceptions and attitudes of participating in the PA of children and adolescents with ID were identified as individual factors influencing their PA participation. For example, lack of understanding on the importance of PA and its benefits to health may inhibit their PA, while enjoyment of PA and wanting to lose weight may promote their PA behavior. Therefore, providing children and adolescents with ID a variety of opportunities to successfully participate in PA may be a logical first step toward increasing enjoyment; this, in turn, could lead to PA becoming a preferred activity [43]. Moreover, there is a need to develop a multimodal intervention that combines PA and health education to further educate them concerning the knowledge and benefits of PA to improve their cognition and promote their positive attitudes toward PA [49].
Parent-related factors were the most frequently reported factor influencing the PA participation of children and adolescents with ID at the interpersonal level. In particular, parental support, as both a barrier and a facilitator, was concluded to be the prominent concern. Sufficient parental support, including parents' positive models, company and supports (e.g., transportation supports, financial supports, providing encouragement) facilitated the PA participation of children and adolescents with ID [48,49,57]. By contrast, lack of parental support and parents' lack of professional knowledge related to PA inhibited the PA participation of their children with ID [38,51,57]. Therefore, being positive role models, supplying company and encouragement, and providing transport and financial support may be the integral 'gatekeeper' roles that parents play in promoting the PA participation of children and adolescents with ID [70,75]. In addition, parents' high levels of overprotection and concerns relating to their child's competence for participating in various physical activities may prevent their child from conducting healthy and helpful physical activities [46,51]. Parents are recommended to learn about related PA guidelines and the safe physical activities available to and appropriate for their children with ID [46]. These findings suggest that greater professional support and advice related to PA participation among children and adolescents with ID need to be offered to parents; in turn, parents could then provide more supports and encouragement for their children.
Social networks were also identified as a key factor influencing the PA participation of children and adolescents with ID at the interpersonal level. The results of this review showed that social connectedness, teamwork, and competition in sporting activities with friends facilitated intrinsic motivation to participate in PA in this population, while a lack of social connectedness leads to feelings of alienation and inactivity [38]. Parents, teachers, and program planners should aim to promote and encourage a social element as a reason to participate in activities, and support children and adolescents with ID to socially interact with peers with and without disabilities to encourage them to participate more in PA [38,75].
PE class-related factors were the most frequently reported factor influencing the PA participation of children and adolescents with ID at the environmental level. This result confirmed the Ecological models of health behavior that emphasize the environmental contexts of behavior [28]. The population of children and adolescents with ID depends more on schools to accumulate their PA, especially the school PE curriculum [38,42]. Previous studies proved that PE lesson contexts focused on skill practice and that high autonomysupportive instructional climates promoted the PA participation of children and adolescents with ID [36,56]. Therefore, during school PE classes, the PE teachers are recommended to make appropriate adaptations to PA programs and choose activities focusing on games and skills to increase the frequency and intensity of activities to make ID students participate in adequate PA [47,58]. They are also recommended to design adapted interventions such as peer-tutored PE programs or group-based activities that can offer the potential for social interaction and support to encourage the students to participate more activities in PE classes [35,39]. However, studies using randomized control trials to examine the effects of the teaching methods of activities on promoting PA during PE classes are still needed.
Environmental facilities and resources and PA programs adapted for children and adolescents with ID available in the communities were also two identified key factors influencing the PA participation of children and adolescents with ID at the environmental level. They were both barriers and facilitators, depending on their adequacy or lack thereof. Adequate and accessible facilities and resources provide a basic guarantee for PA participation of children and adolescents with ID. As part of objective social support, they may improve enjoyment and motivation towards PA, hence increasing the likelihood of PA behavior change [23,76]. Local governments and community organizations should consider improving the accessibilities of facilities or resources in communities, and make efforts to provide more PA programs adapted for children with disabilities, to support the extensive PA participation of children and adolescents with ID [77].
Poor weather was frequently identified as a barrier to the PA participation of children and adolescents with ID at the environmental level. On the one hand, self-efficacy should be strengthened in order for the child to be able to make more effort and overcome difficulties and continue participating in PA in special situations (e.g., poor weather conditions) [76,78]. On the other hand, more indoor-based physical activities should be introduced by parents or schools to replace outdoor activities that are less suitable in real 'bad' weather [49].
The strengths of this paper include the use of a systematic search strategy to conduct a scoping review and produce an extensive yield of relevant literature and its inclusivity of a range of study designs, allowing us to provide a more comprehensive overview of the evidence base. Furthermore, the use of the social ecological model allowed the researchers to explore the multiple influences on PA at different levels. It provided a framework to categorize factors and to highlight where previous research focused and what future research directions are required [19].
Some limitations should also be considered when interpreting the results of this review. Due to the nature of scoping reviews, we did not assess the quality of the included studies, which may have influenced the quality of the results of the studies. This may be a perceived limitation of our methodological frameworks. If possible, it is recommended that quality assessment using validated instruments should be factored into the framework of scoping reviews and add the criteria to the selection of studies to be charted in future research [79]. Language bias may be present because studies that were not written in English were excluded. Finally, the relative importance of each factor should be considered, because the strength of the factor is mostly unclear, and which factor is the most important is uncertain [78]. Therefore, some of the findings should be interpreted with caution. Moreover, issues relevant to the potential limitations of social ecological models need to be considered. The social ecological model has a lack of sufficient specificity to guide conceptualization of a specific problem, identification of appropriate interventions, or clarity in determining when and where to intervene [63]. Given this potential for lack of specificity, theoretical and conceptual development is essential to the advancement of social ecological models to guide the identification of PA factors and target PA promotion among children and adolescents with ID.

Conclusions
This study conducts a scoping review to identify barriers and facilitators of PA participation among children and adolescents with ID based on a social ecological model. The results indicated that disability-specific factors, low self-efficacy, lack of parental support, inadequate or inaccessible facilities, and lack of appropriate programs were the most commonly reported barriers. High self-efficacy, enjoyment of PA, sufficient parental support, social interaction with peers, attending school PE classes, and adapted PA programs were the most commonly reported facilitators. Given the findings from this scoping review, there is a need for continued exploration of the barriers and facilitators of PA participation among children and adolescents with ID by more qualitative, longitudinal, and interventional studies. By understanding the relationships between barriers and facilitators and the different dimensions of PA, interventions can be better designed and adapted to encourage greater PA participation for children and adolescents. Such work may be vital to improve this population's health and growth.