Change in parent and peer support across ages 9 to 15 yr and adolescent girls' physical activity.

PURPOSE: To examine change in parent and peer support for girls' physical activity (PA) across ages 9 to 15 yr and assess if girls who remain active during adolescence are differentially exposed to support when compared with girls who do not remain active.
METHODS: Participants included 174 non-Hispanic white girls assessed at ages 9, 11, 13, and 15 yr. Parental modeling and logistic support for PA were assessed at all ages; peer support was assessed at ages 9, 11, and 13 yr. Minutes per day of moderate-to-vigorous PA (MVPA) was measured at ages 13 and 15 yr using 7-d accelerometry. Girls' body mass index and self-reported PA were measured at ages 9, 11, and 13 yr. Girls were classified as maintaining PA during adolescence if they recorded > or =30 min.d of MVPA at ages 13 and 15 yr. Patterns of change in parent/peer support and differences in exposure to support for girls who maintained PA and those who did not maintain PA were assessed using individual growth curve modeling.
RESULTS: A linear decline was observed in parental modeling. A curvilinear pattern of change was observed for parental logistic support and peer support. Although the rate of change varied by age, logistic support generally decreased, and peer support increased across time. Girls who maintained PA had parents who reported higher modeling of PA across time and stable levels of logistic support. In contrast, girls who did not maintain PA had parents who reported lower modeling and declines in logistic support.
CONCLUSIONS: Parental modeling of PA before adolescence and logistic support during adolescence could help girls establish early patterns of PA and social networks that facilitate maintained PA during adolescence.