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 .
Effectiveness of the ‘Girls Active’ school-based physical activity programme: A cluster randomised controlled trial
Background Globally , adolescent girls ’  physical activity ( PA ) levels are low . The ‘ Girls Active ’ secondary school-based programme , developed by the Youth Sport Trust , aims to increase PA in adolescent girls . This paper explores the effectiveness of the ‘ Girls Active ’ school-based PA programme . Methods A r and om sample of girls aged 11–14 from 20 secondary schools ( Midl and s , UK ) participated in a two-arm cluster r and omised controlled trial . Ten schools received Girls Active and 10 continued with usual practice . Measurements were taken at baseline , seven- and 14-month follow-up . Primary outcome : wrist-worn accelerometer measured moderate- to vigorous-intensity PA ( MVPA ) .  Secondary outcomes : overall PA , light PA , sedentary time , body composition , and psychosocial outcomes . Generalised estimating equations , adjusted for school cluster and potential confounders , were used and A priori subgroup analysis was undertaken . Micro-costing and cost-consequence analyses were conducted using bespoke collection methods on programme delivery information . Outcomes for the cost-consequence analysis were health related quality of life measured by the Child Health Utility-9D and service use . Results Overall , 1752 pupils participated , 1211 ( 69.1 % ) provided valid 14-month accelerometer data . No difference in MVPA ( mins/day ; 95 % confidence intervals ) was found at 14 months ( 1.7 ; -0.8 to 4.3 ) , there was at seven months ( 2.4 ; 0.1 to 4.7 ) . Subgroup analyses showed significant intervention effects on 14-month in larger schools ( 3.9 ; 1.39 to 6.09 ) and in White Europeans ( 3.1 ; 0.60 to 6.02 ) and in early maturers ( 5.1 ; 1.69 to 8.48 ) at seven months . The control group did better in smaller schools at 14-months ( -4.38 ; -7.34 to -1.41 ) . Significant group differences were found in 14-month identified motivation ( -0.09 ; -0.18 to -0.01 ) and at seven months in : overall PA ( 1.39 mg/day ; 0.1 to 2.2 ) , after-school sedentary time ( -4.7 ; -8.9 to -0.6 ) , whole day ( 5.7 ; 1.0 to 10.5 ) and school day ( 4.5 ; 0.25 to 8.75 ) light PA , self-esteem . Small , statistically significant , differences in some psychosocial variables favoured control schools . Micro-costing demonstrated that delivering the programme result ed in a range of time and financial costs at each school . Cost-consequence analysis demonstrated no effect of the programme for health related quality of life or service use . Conclusions Compared with usual practice , ‘ Girls Active ’ did not affect 14-month MVPA.Trial registration IS RCT
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 .