A longitudinal, two-cohort study of parenting influences on adolescent physical activity and screen-time during the transition to secondary school in British Columbia.

Objective: Parents influence children's lifestyle behaviors, though this influence may decline as children gain autonomy. However, the COVID-19 pandemic likely altered these dynamics due to increased time at home. We examined whether associations between parenting practices and adolescents' physical activity and recreational screen-time changed during the transition to secondary school in two cohorts: one assessed pre-pandemic and one during the pandemic. Methods: Data were collected in British Columbia (2018-2021) at two time points (elementary and secondary school) among 689 parent-adolescent dyads (parent age: 46 ± 5.4 years, 73 % mothers; child age: 13 ± 0.3 years, 52 % female). Forty-two percent were assessed pre-pandemic, and 58 % during the pandemic. Both cohorts self-reported parenting practices, recreational screen-time, and physical activity; non-pandemic children also wore accelerometers. Mixed-effect models with parenting-by-grade interaction terms assessed within-cohort changes over time. Results: Supportive parenting predicted lower self-reported recreational screen-time and higher moderate-to-vigorous physical activity (MVPA) (non-pandemic: b = -25, 95 %CI:-38,-12 & b = 0.66, 95 %CI:0.38,0.93; pandemic: b = -19, 95 %CI:-30,-8 & b = 0.63, 95 %CI:0.32,0.93). In non-pandemic families, supportive parenting also predicted weekday light and MVPA (b = 12, 95 %CI:4,21 & b = 9, 95 %CI:4,14), though the latter significantly weakened post-transition (b = -11, 95 %CI:-19,-2). Conclusions: Our findings highlight the importance of positive parenting in supporting children's active lifestyles, particularly during key life transitions.