The relative decline in MVPA affects both sexes from an early age ; however , it is greater among girls .
Moderate-to-vigorous-intensity  physical activity ( MVPA )  is important for childhood obesity prevention and treatment , yet declines with age .
Timing and magnitude of the decline in MVPA in children and adolescents are unclear but important for informing effective obesity intervention development .
This systematic review aim ed to determine and compare the year-to-year changes in MVPA among children and adolescents .
The Physical Activity 4 Everyone Cluster Randomized Trial: 2-Year Outcomes of a School Physical Activity Intervention Among Adolescents.
INTRODUCTION Few interventions have been successful in reducing the physical activity decline typically observed among adolescents . The aim of this paper is to report the 24-month effectiveness of a multicomponent school-based intervention ( Physical Activity 4 Everyone ) in reducing the decline in moderate to vigorous physical activity ( MVPA ) among secondary school students in disadvantaged areas of New South Wales , Australia . STUDY DESIGN A cluster RCT was conducted in five intervention and five control schools with follow-up measures taken at 24 months post-r and omization . SETTING / PARTICIPANTS The trial was undertaken within secondary schools located in disadvantaged communities in New South Wales , Australia . INTERVENTION A multicomponent school-based intervention based on the Health Promoting Schools Framework was implemented . The intervention consisted of seven physical activity promotion strategies that targeted the curriculum ( teaching strategies to increase physical activity in physical education lessons , student physical activity plans , and modification of school sport program ) ; school environment ( recess/lunchtime activities , school physical activity policy ) ; parents ( parent newsletters ) ; and community ( community physical activity provider promotion ) . Six additional strategies supported school implementation of the physical activity intervention strategies . MAIN OUTCOME MEASURE Minutes per day spent in MVPA , objective ly measured by accelerometer . RESULTS Participants ( N=1,150 , 49 % male ) were a cohort of students aged 12 years ( Grade 7 ) at baseline ( March-June 2012 ) and 14 years ( Grade 9 ) at follow-up ( March-July 2014 ) . At 24-month follow-up , there were significant effects in favor of the intervention group for daily minutes of MVPA . The adjusted mean difference in change in daily MVPA between groups was 7.0 minutes ( 95 % CI=2.7 , 11.4 , p<0.002 ) ( analysis conducted December 2014-February 2015 ) . Sensitivity analyses based on multiple imputation were consistent with the main analysis ( 6.0 minutes , 95 % CI=0.6 , 11.3 , p<0.031 ) . CONCLUSIONS The intervention was effective in increasing adolescents ' minutes of MVPA , suggesting that implementation of the intervention by disadvantaged schools has the potential to slow the decline in physical activity . TRIAL REGISTRATION Australian New Zeal and Clinical Trials Registry ACTRN12612000382875
The relative decline in MVPA affects both sexes from an early age ; however , it is greater among girls .
Moderate-to-vigorous-intensity  physical activity ( MVPA )  is important for childhood obesity prevention and treatment , yet declines with age .
Timing and magnitude of the decline in MVPA in children and adolescents are unclear but important for informing effective obesity intervention development .
This systematic review aim ed to determine and compare the year-to-year changes in MVPA among children and adolescents .