title: Tracking of accelerometer-measured physical activity in early childhood.
abstract: Establishing and maintaining healthy physical activity (PA) levels is important throughout life. The purpose of this study was to determine the extent of PA tracking between ages 3 and 7 y. Objective measures of PA (RT3, triaxial accelerometer) were collected every 4 mo from ages 3-7; data from 234 children with PA measures available during each year of age were analyzed. Mean PA (total, moderate/vigorous (MV), and inactivity [IA]) was calculated for each year of age and adjusted for wear time. Correlations with age 3 PA were moderate at age 4 (r = .42-.45) but declined by age 7 (r = .19-.25). After classification into sex-specific tertiles of PA at age 3, boys in the high age 3 MVPA tertile maintained significantly higher PA at all subsequent ages, while girls in the high age 3 MVPA tertile were not significantly higher at age 6 and 7. Boys and girls in the high age 3 IA tertile had significantly higher IA at multiple subsequent years of age (p < .05 at ages 5 and 6). In conclusion, boys who were relatively more active at age 3 remained more active for several subsequent years. These findings highlight early-childhood differences in physical activity patterns between boys and girls.
authors.affiliation: Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Edwards
authors.forename: Philip R
authors.initials: PR
authors.lastname: Khoury
authors.forename: Heidi J
authors.initials: HJ
authors.lastname: Kalkwarf
authors.forename: Jessica G
authors.initials: JG
authors.lastname: Woo
authors.forename: Randal P
authors.initials: RP
authors.lastname: Claytor
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Daniels
mesh_terms: D061725:Accelerometry / Q000379:methods*; D000367:Age Factors; D000704:Analysis of Variance; D000886:Anthropometry; D015992:Body Mass Index; D002648:Child; D002657:Child Development / Q000502:physiology; D002675:Child, Preschool; D015444:Exercise / Q000502:physiology*; D005260:Female; D005431:Florida; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D009043:Motor Activity / Q000502:physiology*; D015999:Multivariate Analysis; D012737:Sex Factors; D013997:Time Factors