Screen time and passive school travel as independent predictors of cardiorespiratory fitness in youth

Objective: The most prevalent sedentary behaviours in children and adolescents are engagement with small screen media (screen-time) and passive travel (by motorised vehicle). The objective of this research was to assess the independence of these behaviours from one another and from physical activity as predictors of cardiorespiratory fitness in youth. Methods: We measured cardiorespiratory fitness in n = 6819 10-16. year olds (53% male) who self-reported their physical activity (7-day recall) school travel and screen time habits. Travel was classified as active (walking, cycling) or passive; screen time as < 2. h, 2-4 h or > 4 h. Results: The multivariate odds of being fit were higher in active travel (Boys: OR 1.32, 95% CI: 1.09-1.59; Girls: OR 1.46, 1.15-1.84) than in passive travel groups. Boys reporting low screen time were more likely to be fit than those reporting > 4 h (OR 2.11, 95% CI: 1.68-2.63) as were girls (OR 1.66, 95% CI: 1.24-2.20). These odds remained significant after additionally controlling for physical activity. Conclusion: Passive travel and high screen time are independently associated with poor cardiorespiratory fitness in youth, and this relationship is independent of physical activity levels. A lifestyle involving high screen time and habitual passive school travel appears incompatible with healthful levels of cardiorespiratory fitness in youth. © 2012 Elsevier Inc.