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 .
Evidence for increased bone formation following a brief endurance-type training intervention in adolescent males.
The effect of exercise training , particularly relatively brief periods , on bone turnover markers in adolescents has been poorly studied . Thirty-eight healthy males ( 16+/-0.7 years ) participated in a 5-week  summer school program in which 20 subjects were r and omly assigned to a training group consisting of 2 h/day , 5 days/week of endurance exercise , and 18 subjects were assigned to a control group .  Bone formation was assessed by measurements of circulating osteocalcin , bone-specific alkaline phosphatase ( BSAP ) , and the C-terminal procollagen peptide ( PICP ) . Bone resorption was assessed by urinary levels of free deoxypyridinoline cross-links ( dPYR ) and the C-(CTX ) and N-terminal ( NTX ) telopeptide cross-links . Prior to training , there was a weak positive correlation between fitness and PICP ( r = 0.27 , p < 0.05 ) , but no correlations were observed between fitness and either the other markers of bone formation or bone resorption . Training led to a significant increase in ( 1 ) osteocalcin ( 15+/-4 % , p < 0.03 ) , ( 2 ) BSAP ( 21+/-6 % , p < 0.02 ) , and ( 3 ) PICP ( 30+/-11 % , p < 0.03 ) and to a significant decrease in NTX ( -21 + /- 3 % , p < 0.05 ) . These bone turnover markers did not change in the control subjects ( osteocalcin , 0+/-4 % ; BSAP , 2+/-4 % ; PICP , -4 + /- 6 % ; NTX , -6 + /- 4 % ) . There was no change in urinary dPYR and CTX in either control or trained subjects . Fitness is only weakly , if at all , correlated with bone formation , but a relatively brief period of endurance training leads to a substantial increase in bone formation markers in adolescent males . School-based , short-term exercise training programs could play a role in enhancing bone formation in adolescents
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 .