You might think that the younger we are, the more active we are. But a new study turns that belief on its head: The results show that physical activity is lower in children than previously thought. And, on average, teens are about as sedentary as a 60-year-old adult.

The study, conducted by researchers from the Johns Hopkins Bloomberg School of Public Health, shows that by the end of adolescence, activity levels were alarmingly low. The only age group with an increase in activity is young adults in their 20s. After that, activity levels begin to decline starting at age 35, and continue to fall through midlife and older adulthood, the study shows.

The researchers used data from the National Health and Nutrition Examination Survey from 2003-2006, in which nearly 13,000 participants wore tracking devices for seven straight days, removing them only for bathing and at bedtime. The devices measured how much time participants were sedentary or engaged in light or moderate-to-vigorous physical activity.

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