To be eligible for the review, studies had to be of an intervention that promoted physical activity based in the after-school setting, and had to include an outcome measure of physical activity. Studies that assessed both physical activity and physical fitness were included but those that focused only on physical fitness were excluded. Study participants needed to be less than 18 years old. Obesity treatment studies were excluded but those aimed at preventing overweight/obesity were included. Unpublished articles, conference papers and dissertations were excluded.
It appeared that study selection was conducted by one reviewer with 10% of included and excluded papers checked by another member of the team.
Most studies were conducted in the USA with half of all included studies aimed at the African-American population. Most children were of primary school age. Where stated, percentage of males ranged from 0 to 58%. A number of studies were targeted at those already overweight or obese. Half of the studies included a family component in the intervention. Intervention targets included prevention of weight gain, physical activity and/or its psychosocial determinants, and physical activity plus fruit and vegetable intake combined. Studies varied in duration from four weeks to two years with most lasting 12 weeks or less. The review included both individual and cluster randomised trials, non-randomised controlled trials and pre-post trials. Physical activity outcomes were assessed using accelerometry and/or participants self-report.