Cochrane Database Syst Rev. 2013 Feb 28;2:CD007651. doi: 10.1002/14651858.CD007651.pub2.
BACKGROUND: The World Health Organization (WHO) estimates that 1.9 million deaths
worldwide are attributable to physical inactivity and at least 2.6 million deaths
are a result of being overweight or obese. In addition, WHO estimates that
physical inactivity causes 10% to 16% of cases each of breast cancer, colon, and
rectal cancers as well as type 2 diabetes, and 22% of coronary heart disease and
the burden of these and other chronic diseases has rapidly increased in recent
decades.
OBJECTIVES: The purpose of this systematic review was to summarize the evidence
of the effectiveness of school-based interventions in promoting physical activity
and fitness in children and adolescents.
SEARCH METHODS: The search strategy included searching several databases to
October 2011. In addition, reference lists of included articles and background
papers were reviewed for potentially relevant studies, as well as references from
relevant Cochrane reviews. Primary authors of included studies were contacted as
needed for additional information.
SELECTION CRITERIA: To be included, the intervention had to be relevant to public
health practice (focused on health promotion activities), not conducted by
physicians, implemented, facilitated, or promoted by staff in local public health
units, implemented in a school setting and aimed at increasing physical activity,
included all school-attending children, and be implemented for a minimum of 12
weeks. In addition, the review was limited to randomized controlled trials and
those that reported on outcomes for children and adolescents (aged 6 to 18
years). Primary outcomes included: rates of moderate to vigorous physical
activity during the school day, time engaged in moderate to vigorous physical
activity during the school day, and time spent watching television. Secondary
outcomes related to physical health status measures including: systolic and
diastolic blood pressure, blood cholesterol, body mass index (BMI), maximal
oxygen uptake (VOmax), and pulse rate.
DATA COLLECTION AND ANALYSIS: Standardized tools were used by two independent
reviewers to assess each study for relevance and for data extraction. In
addition, each study was assessed for risk of bias as specified in the Cochrane
Handbook for Systematic Reviews of Interventions. Where discrepancies existed,
discussion occurred until consensus was reached. The results were summarized
narratively due to wide variations in the populations, interventions evaluated,
and outcomes measured.
MAIN RESULTS: In the original review, 13,841 records were identified and
screened, 302 studies were assessed for eligibility, and 26 studies were included
in the review. There was some evidence that school-based physical activity
interventions had a positive impact on four of the nine outcome measures.
Specifically positive effects were observed for duration of physical activity,
television viewing, VO max, and blood cholesterol. Generally, school-based
interventions had little effect on physical activity rates, systolic and
diastolic blood pressure, BMI, and pulse rate. At a minimum, a combination of
printed educational materials and changes to the school curriculum that promote
physical activity resulted in positive effects.In this update, given the addition
of three new inclusion criteria (randomized design, all school-attending children
invited to participate, minimum 12-week intervention) 12 of the original 26
studies were excluded. In addition, studies published between July 2007 and
October 2011 evaluating the effectiveness of school-based physical interventions
were identified and if relevant included. In total an additional 2378 titles were
screened of which 285 unique studies were deemed potentially relevant. Of those
30 met all relevance criteria and have been included in this update. This update
includes 44 studies and represents complete data for 36,593 study participants.
Duration of interventions ranged from 12 weeks to six years.Generally, the
majority of studies included in this update, despite being randomized controlled
trials, are, at a minimum, at moderate risk of bias. The results therefore must
be interpreted with caution. Few changes in outcomes were observed in this update
with the exception of blood cholesterol and physical activity rates. For example
blood cholesterol was no longer positively impacted upon by school-based physical
activity interventions. However, there was some evidence to suggest that
school-based physical activity interventions led to an improvement in the
proportion of children who engaged in moderate to vigorous physical activity
during school hours (odds ratio (OR) 2.74, 95% confidence interval (CI), 2.01 to
3.75). Improvements in physical activity rates were not observed in the original
review. Children and adolescents exposed to the intervention also spent more time
engaged in moderate to vigorous physical activity (with results across studies
ranging from five to 45 min more), spent less time watching television (results
range from five to 60 min less per day), and had improved VOmax (results across
studies ranged from 1.6 to 3.7 mL/kg per min). However, the overall conclusions
of this update do not differ significantly from those reported in the original
review.
AUTHORS' CONCLUSIONS: The evidence suggests the ongoing implementation of
school-based physical activity interventions at this time, given the positive
effects on behavior and one physical health status measure. However, given these
studies are at a minimum of moderate risk of bias, and the magnitude of effect is
generally small, these results should be interpreted cautiously. Additional
research on the long-term impact of these interventions is needed.
