Measuring physical activity in children and youth living with intellectual disabilities: a systematic review.

Accurate assessment of physical activity is necessary in determining levels of physical activity in children living with intellectual disability (ID) and assessing effectiveness of intervention programmes. A systematic review of measures of physical activity in children with ID was undertaken using the PRISMA guidelines. MEDLINE-PubMed, Scopus, CINAHL Plus with Full Text and SPORT Discus (up to May 2012) databases were searched and articles were identified. The following inclusion criteria were used; articles in English which reported original research and measured physical activity levels in children with ID, and participants of school age (5-18 years). Searches were limited to articles from peer-reviewed journals and those available in full text. The search identified 5087 titles. Seventy-eight articles were retained for full review and 30 met the inclusion criteria. The review identified a clear deficiency in the number of validity and reliability studies of tools used to quantify physical activity in children with ID. Objective measurement of physical activity provided consistent results. Despite the differences in study design and methodological quality, there was agreement among studies that children with ID were significantly less active compared to children without disabilities. Refusal to wear instruments, movement limitations in children with ID, and positioning of devices were common issues. Future studies should focus on determining the validity and reliability of tools used to assess physical activity in children with ID.