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.

Higher physical activity (PA) levels will obtain more health-related benefits for children and adolescents with intellectual disabilities (ID). The mastery of fundamental movement skills (FMS) potentially correlates with PA. This study aimed to examine the associations of FMS with moderate-to-vigorous intensity physical activity (MVPA) levels in children and adolescents with moderate to severe ID. Moreover, this research analyzes whether there are gender and age differences in the association between these two variables. A total of 93 children and adolescents with ID, aged 8–17 years (mean age = 13.27; SD = 3.35), were recruited from a special school located in western China. The time spent in MVPA was measured using waist-worn accelerometers. FMS proficiency was assessed using the Test of Gross Motor Development 2 (TGMD-2). Children and adolescents with ID tend to have delayed maturity of FMS patterns (locomotor skills t (92) = −16.91, p < 0.001, d = 2.48; object control skills t (92) = −25.39, p < 0.001, d = 3.72; total FMS t (92) = −21.83, p < 0.001, d = 3.20) and lower proficiency in objective control skills (t (92) = 3.989, p < 0.001, d = 0.29). A significant positive correlation was found between MVPA and FMS, and this association was moderated by gender and age. For boys, object control skills were a significant predictor of MVPA time (B = 0.842, p < 0.01), whereas locomotor skills were a significant predictor of MVPA time (B = 0.472, p < 0.05) for girls. For children with ID, object control skills were a significant predictor of MVPA time (B = 0.736, p < 0.05). Proficiency in FMS has a positive effect on increasing the level of MVPA in children and adolescents with ID. Gender and age factors should be considered when implementing FMS intervention programs.