Associations between after-school physical activity, television use, and parental strategies in a sample of New Zealand adolescents

Background: Youth display suboptimal levels of physical activity and sedentary behaviors. Few studies have examined the existence of the "displacement hypothesis" or the effect of parental strategies on activity behaviors during the after-school period. Methods: A total of 3471 students (12-18 years old) completed a self-report survey that assessed after-school physical activity and television (TV) use and perceived parental strategies (ie, encouragement to be active, TV-viewing rules). Participants were grouped into 4 activity groups: high TV/low active, high TV/active, low TV/low active, or low TV/active. Descriptive statistics and nominal logistic-regression analyses were conducted. Results: Compared with students who watched less than 1 h of TV, participants who watched ≥4 h of TV were half as likely to be active after school (≥4 h; adjusted odds ratio 0.51, 95% CI .40-.65). Compared with the low TV/active group, the other activity groups were at least 1.28 times more likely to have parents that provided only 1 parental strategy (encouragement for activity or TV rules) and up to 4.7 times more likely to have parents that provided neither strategy. Discussion: Sedentary behaviors are associated with displacement of active pursuits. Parental strategies exert a strong influence on after-school behaviors of high school students.