In a recent New York Times article, by Nicholas Bakalar, "Children Move Less Starting at Age 6," children's sedentary activity builds up as early as age 6 and increases by two hours or more per day by the time they are age 11. This finding goes against conventional wisdom of sedentary behavior starting in adolescence.
According to the study, in Pediatrics, only 63 percent of 11-year-olds were getting the recommended 60 minutes a day of moderate to vigorous exercise, compared with 82 percent of 6-year-olds.
The authors incite the need for interventions beginning with the younger children instead of the adolescents.
Read more in this New York Times Article.