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 .
Developmental Trajectories of Physical Activity, Sports, and Television Viewing During Childhood to Young Adulthood: Iowa Bone Development Study.
IMPORTANCE The diverse developmental patterns of obesogenic behaviors during childhood and adolescence can be better understood by using new analytic approaches to assess the heterogeneity in variation during growth and development and to map the clustering of behavior patterns . OBJECTIVES To identify distinct trajectories of daily time spent in  moderate- to vigorous-intensity physical activity ( MVPA )  from ages 5 to 19 years and to examine the associations of MVPA trajectories with sports participation and television viewing trajectories . DESIGN , SETTING , AND PARTICIPANTS Cohort members in the prospect i ve population -based Iowa Bone Development Study participated in  MVPA assessment s via accelerometry from September 16 , 1998 , to December 9 , 2013 , at ages 5 , 8 , 11 , 13 , 15 , 17 , and 19 years and completed a question naire every 6 months on sports participation and daily time spent in television viewing . MAIN OUTCOMES AND MEASURES Trajectories of MVPA ( minutes per day ) , participation in organized sports ( yes or no ) , and television viewing time ( hours per day ) . RESULTS Based on the data from 537 participants ( 50.1 % females ; 94.6 % white ) , we identified 4 MVPA trajectories : consistently inactive ( 14.9 % ) , consistently active ( 18.1 % ) , decreasing moderate physical activity ( 52.9 % ) , and substantially decreasing high physical activity ( 14.1 % ) . All participants in the consistently inactive trajectory also followed a trajectory of no participation in sports . The consistently active trajectory was associated with decreasing an already low television viewing trajectory ( P < .001 ) . CONCLUSIONS AND RELEVANCE This study provided a nuanced look at the known decrease in MVPA during childhood and adolescence . Sports participation could be a critical way to avoid the consistently inactive pattern . Most important , we identified a subset of participants who maintained a seemingly healthy level of MVPA from childhood to young adulthood . The developmental pathways of physical activity and television viewing behaviors could be related . Additional studies should examine the determinants and health consequences of these specific MVPA trajectories
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 .