title: Developmental Trajectories of Physical Activity, Sports, and Television Viewing During Childhood to Young Adulthood: Iowa Bone Development Study.
abstract: OBJECTIVE
  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.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  Cohort members in the prospective population-based Iowa Bone Development Study participated in MVPA assessments via accelerometry from September 16, 1998, to December 9, 2013, at ages 5, 8, 11, 13, 15, 17, and 19 years and completed a questionnaire every 6 months on sports participation and daily time spent in television viewing.
  
  
  METHODS
  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
  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.
authors.affiliation: Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois.
authors.forename: Soyang
authors.initials: S
authors.lastname: Kwon
authors.affiliation: Department of Health and Human Physiology, University of Iowa, Iowa City.
authors.forename: Kathleen F
authors.initials: KF
authors.lastname: Janz
authors.affiliation: Department of Epidemiology, University of Iowa, Iowa City.
authors.forename: Elena M
authors.initials: EM
authors.lastname: Letuchy
authors.affiliation: Department of Epidemiology, University of Iowa, Iowa City.
authors.forename: Trudy L
authors.initials: TL
authors.lastname: Burns
authors.affiliation: Department of Preventive and Community Dentistry, University of Iowa, Iowa City.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Levy
mesh_terms: D061725:Accelerometry; D000293:Adolescent; D001846:Bone Development; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D015444:Exercise / Q000502:physiology*; D005260:Female; D006304:Health Status; D006801:Humans; D007484:Iowa; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity; D011446:Prospective Studies; D012307:Risk Factors; D013177:Sports / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires; D013690:Television / Q000706:statistics & numerical data*