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 .
ENERGY BALANCE IN ADOLESCENT GIRLS: THE TRIAL OF ACTIVITY FOR ADOLESCENT GIRLS COHORT
Objectives To study correlates of change in BMI percentile and body fat among adolescent girls Design and Methods A longitudinal prospect i ve study following 265 girls from the Trial of Activity for Adolescent Girls ( TAAG ) cohort measured in 8th grade and during 10 and 11th grade or 11th and 12th grade . Twice during 2009 - 2011 girls wore an accelerometer and completed a food frequency question naire and 7-day diary documenting trips and food eaten away from home and school . Physical activity , BMI , and percent body fat were objective ly measured at each time point . Results Moderate to vigorous physical activity ( MVPA ) declined , but was not independently associated with changes in BMI percentile . Increased vigorous physical activity was associated with reductions in body fat . Diet was associated with both changes in BMI percentile and body fat . Girls who increased the percentage of caloric intake from snacks and desserts reduced their BMI percentile and body fat . Conclusions Some relationships between energy balance behaviors and BMI and body composition were counter-intuitive . While it is plausible that vigorous activity would result in reductions of body fat , until more accurate methods are devised to measure diet , the precise contribution of dietary composition to health will be difficult to assess
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 .