LAUSR

Purpose We aimed to examine the longitudinal associations between parents' and youth's participation in physical activity (PA). Methods One hundred and ninety youth completed self-administered questionnaires 3 times per year from 2011 to 2015, and their parents completed an interviewer-administered questionnaire during a telephone interview once in 2011–2012. Data on youth's and parents' activities were classified as interdependent or coactive/independent. Results Youth with one or both parents who participated in interdependent activities were more likely to maintain participation in interdependent activities (hazard ratio (HR) = 3.63; 95% confidence interval (CI) = 1.30–10.17). Youth's sustained participation in coactive/independent activities was not associated with parents' participation in coactive/independent activities (HR = 0.97; 95%CI = 0.46–2.06). Conclusion Longitudinal associations between parents' and youth's participation in PA differed across type of PA. Encouraging parents' participation in interdependent activities may promote sustained participation in interdependent activities in youth.