title: Individual, social, and environmental influences on the transitions in physical activity among emerging adults.
abstract: Youth's physical activity (PA) may change across developmental periods. Although previous studies have observed a decline in levels of PA during adolescence, few studies have explored trends in PA during the transition from adolescence to young adulthood and what factors may impact the transitional change. The purpose of this study was to examine changes and predictors of change over time in PA from 10(th) grade to post-high school.
  
  
  
  The NEXT Generation Health Study recruited a nationally-representative cohort of US 10(th)-graders, and administered longitudinal surveys in four waves (years) to follow up the participants to their first year after high school. Using transition models, the self-reported outcomes, moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) each of which was repeatedly measured by one question, were modelled in association with wave-4 environmental-status variables and time-varying covariates.
  
  
  
  There was a continuous decline in the proportion of respondents who met or exceeded the minimum recommended level for either MVPA (from 55.97 to 34.33 %) or VPA (from 65.96 to 54.90 %) from W1 to W4. Higher scores of peer PA, family support and VPA planning were prospectively associated with higher likelihood of meeting the MVPA/VPA recommendations. At wave 4, compared to those not working, attending 4-year colleges, or living on campus, participants working full/part time, not attending school or attending community-college level schools, and living at home or in own place were more likely to engage in MVPA.
  
  
  
  Peer PA, family support, self-regulatory skills, and environmental status after high school are critical factors that can promote MVPA/VPA among adolescents and emerging adults.
authors.affiliation: Department of Health & Exercise Science, Colorado State University, B 215E Moby Complex, Fort Collins, CO, 80523, USA. kaigang.li@colostate.edu.
authors.forename: Kaigang
authors.initials: K
authors.lastname: Li
authors.affiliation: Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health & Human Development, 6100 Executive Blvd, Bethesda, MD, 20892-7510, USA.
authors.forename: Danping
authors.initials: D
authors.lastname: Liu
authors.affiliation: Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health & Human Development, 6100 Executive Blvd, Bethesda, MD, 20892-7510, USA.
authors.forename: Denise
authors.initials: D
authors.lastname: Haynie
authors.affiliation: Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health & Human Development, 6100 Executive Blvd, Bethesda, MD, 20892-7510, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gee
authors.affiliation: University of Waterloo, 200 University Ave W, Waterloo, ON, N2L 3G1, Canada.
authors.forename: Ashok
authors.initials: A
authors.lastname: Chaurasia
authors.affiliation: Indiana University School of Public Health, Bloomington, IN, 47405, USA.
authors.forename: Dong-Chul
authors.initials: DC
authors.lastname: Seo
authors.affiliation: The CDM Group, 7500 Old Georgetown Road, Bethesda, MD, 20814, USA.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Iannotti
authors.affiliation: Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health & Human Development, 6100 Executive Blvd, Bethesda, MD, 20892-7510, USA.
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Simons-Morton
mesh_terms: D000293:Adolescent; D000328:Adult; D004651:Employment; D004777:Environment; D015444:Exercise; D005190:Family; D005260:Female; D015438:Health Behavior; D006801:Humans; D008016:Life Change Events; D008137:Longitudinal Studies; D008297:Male; D010379:Peer Group; D026684:Personal Autonomy; D012111:Residence Characteristics; D012574:Schools; D012931:Social Environment; D011795:Surveys and Questionnaires; D014481:United States; D014495:Universities; D055815:Young Adult
keywords: Emerging adults; Moderate and vigorous physical activity; Peer physical activity; Physical activity planning; Transition model