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 , VO2 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 material s and changes to the school curriculum that promote physical activity result ed in positive effects .
Few changes in outcomes were observed in this up date 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 .
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 .
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 .
Changes in sedentary behavior among adolescent girls: a 2.5-year prospective cohort study.
PURPOSE To describe longitudinal changes in  leisure-time sedentary behavior  among girls , during early to mid-adolescence . METHODS A 2.5-year prospect i ve cohort study , comprising 5 data collection s , 6 months apart , between 2000 and 2002 . Girls aged 12 - 15 years ( n = 200 ) from 8 high schools located in Sydney , Australia , self-reported the usual time spent each week in a comprehensive range of sedentary behaviors . RESULTS Retention rate for the study was 82 % . Girls aged 12.8 years spent approximately 45 % of their discretionary time in sedentary behavior , which increased to 63 % at age 14.9 years .  Watching TV , videos , and playing video games ( small screen recreation ; SSR ) was the most popular sedentary pastime , accounting for 33 % of time spent in sedentariness , followed by homework and reading ( 25 % ) . Sedentary behavior increased 1.4 and 3.3 hours on week and weekend days , respectively . On weekdays , increased time was spent on hobbies ( 27 min/day ) and on weekend days , increased time was spent sitting around talking with friends ( 60 min/day ) , computer use ( 37 min/day ) , and television viewing ( 34 min/day ) . CONCLUSIONS Among girls , the transition between early and mid-adolescence was accompanied by a significant increase in leisure-time sedentary behavior . Interventions to reduce sedentariness among adolescent girls are best to focus on weekend behaviors . Studies seeking to examine the association between inactivity and the development of chronic health problems need to examine a diverse range of activities that comprehensively measure sedentariness . This information will provide a better underst and ing of inactivity patterns among adolescent girls
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 , VO2 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 material s and changes to the school curriculum that promote physical activity result ed in positive effects .
Few changes in outcomes were observed in this up date 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 .
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 .
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 .