Independence of physical activity and screen time as predictors of cardiorespiratory fitness in youth

Screen time (ST) is associated with physical activity (PA) levels. We aimed to investigate the relationship between ST and fitness. We assessed fitness and daily ST in 7,466 10–16-y-old schoolchildren from the east of England. The differences in fitness between ST groups, and the association between ST and fitness were assessed. ST was negatively associated with fitness in boys of all ages (P < 0.001) and girls in grades 6–9 (P < 0.005). Boys...