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 .
Longitudinal changes in vigorous intensity physical activity from childhood to adolescence: Gateshead Millennium Study.
OBJECTIVE The aims of our study were to quantify levels and investigate sex-specific changes and trajectories in VPA longitudinally from age 7 to 15 years . DESIGN Longitudinal observational study . METHODS Participants were part of the Gateshead Millennium Study . Measures were taken at age 7 ( n=507 ) , 9 ( n=510 ) , 12 ( n=425 ) and 15 years ( n=310 ) .  Vigorous physical activity was quantified objective ly using ActiGraph GT1 M accelerometers over 5 - 7days at the four time-points . Multilevel linear spline r and om-effects model and trajectory analysis to identify sub-groups were performed . RESULTS In boys , average VPA declined across childhood followed by an increase at adolescence , while in girls , average VPA declined across the 8-year study period . In boys , daily VPA decreased from 9 - 12 years ( 1.70minutes/year ) and increased from 12 - 15 years ( 1.99minutes/year ) ( all p < 0.05 ) . In girls daily VPA decreased from 7 - 9 years ( 1.70minutes/year ) ( p < 0.05 ) . Three VPA trajectories were identified which differed between the sexes . In boys , one group decreased from an initial relatively high level , one group , initially relatively low , increased , whereas the third one was stable over the 8-year period . In girls , all three groups declined from baseline . CONCLUSIONS Marked sex and age-specific trajectories in VPA change were observed . These novel findings should help sports and exercise medicine specialists , as well as policy makers , in their effort to maintain or increase VPA in childhood and adolescence
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 .