The authors concluded that the evidence was insufficient to establish conclusive effects of recess-based interventions on school children's levels of physical activity. These cautious conclusions reflect the evidence presented and are likely to be reliable.

To examine the effects of recess-based interventions on the physical activity levels of school-aged children and adolescents.

Six databases including PubMed, SPORTDiscus and The Cochrane Library were searched for peer-reviewed articles published in English from January 2000 to April 2011. Search terms were reported. Bibliographies and authors’ personal collections were searched.

Eligible studies reported interventions to promote physical activity of children and/or adolescents during school recess and/or lunchtime periods. Participants had to be aged between five and 18 years old. Studies had to report a measure of physical activity as an outcome.

All the studies were controlled trials, including randomised controlled trials (RCTs). More than half of the trials were conducted in the UK and the others were in Belgium, Cyprus and USA. More than half of the trials targeted schools in lower socioeconomic areas (where reported). The mean age of participants ranged from five to 11 years (where reported). Interventions were conducted either as single or multiple strategies. Components included playground markings, physical structures, colour-coded playground areas and zones, games equipment and active video games. Physical activity outcomes were measured objectively using heart-rate monitors, accelerometers, pedometers and direct observation; these measures were applied alone or as a combination. For most trials physical activity variables included percentage of moderate to vigorous physical activity (MVPA) and vigorous physical activity (VPA). Recess breaks varied between studies.

Two reviewers independently selected studies for inclusion.

Study quality was assessed using an adapted published eight-item assessment scale with criteria of baseline characteristics reported, randomisation procedure, use of validated outcome measures, outcomes measured after a minimum of six months pre-test, potential confounders, summary results reported, power calculation reporting and comparable timing of outcome measures. Quality was considered high for RCTs if 5 or more points were scored, and high for controlled trials if 4 or more points were scored.

Two reviewers independently assessed study quality. Disagreements were resolved by consensus.

Data were extracted for physical activity outcomes. The authors did not report how many reviewers extracted data.

Data were combined in a narrative synthesis. Levels of evidence for the effect of each intervention strategy were rated as strong, moderate, limited, inconclusive or no evidence when at least two-thirds of the studies reported significant positive results. Studies had to have 250 participants to be considered large when considering levels of evidence.

Nine trials were included in the review: eight RCTs and one controlled trial. Sample sizes ranged from 28 to 470 children; one trial enrolled multiple schools and enrolled on average 667 children at each school. Three trials were reported to be of high methodological quality. None of the RCTs adequately reported randomisation procedures. No trials reported use of power calculations. Follow-up was four to six weeks in five trials and three to 12 months for the other four trials.

Five trials reported a positive effect of the interventions on children’s physical activity levels during school recess and four of these trials reported a statistically significant increase in MVPA (range 4% to 12.9%) using playground markings and games equipment. One trial that evaluated a video gaming intervention reported a decrease in MVPA. One trial that evaluated playground markings and recess walking clubs reported a decrease for boys in MVPA after the intervention. Compared to controls, playground markings and games equipment significantly increased children’s recess and lunchtime moderate physical activity and vigorous physical activity (three trials). Trials that evaluated combined interventions reported mixed findings. There were no studies of recess interventions in adolescent populations.

The evidence was insufficient to establish conclusive intervention effects on children’s recess physical activity.

The review question and inclusion criteria were clearly defined. Several relevant sources were searched. The limitation to studies published in English meant that some data may have been missed. Study quality was assessed and the results were reported in full; few high quality studies were included. Appropriate methods were used to reduce reviewer error and bias during study selection and validity assessment; whether similar methods were used for data extraction was unclear.

A narrative synthesis was appropriate given the variations in study design (cluster or individual level randomisation), quality, interventions and outcomes. Only a small number of studies were included in the review and only four of these were considered large (>250 children). Most studies had short-term follow-up.

The authors’ cautious conclusions reflect the evidence presented are likely to be reliable.

Practice: The authors did not state any implications for practice.

Research: The authors stated that further robust research was needed to strengthen published findings to inform recess physical activity interventions. Further research was particularly needed in adolescent groups and on policy and social variables.

National Heart Foundation of Australia Career Development Fellowship; Australian Research Council Discovery Early Career Researcher Award.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.