Kids are just a bunch of couch potatoes.

A new Johns Hopkins study found that many teens are as sedentary as people their grandparents’ age.

“Activity levels at the end of adolescence were alarmingly low, and by age 19, they were comparable to 60-year-olds,” says Vadim Zipunnikov, the study’s author and an assistant professor at Johns Hopkins’ Bloomberg School of Public Health.

To get a sense of peoples’ physical activity at different stages of life, scientists looked at survey data from 12,529 people, who wore tracking devices for a week to measure their physical activity.

They discovered that kids and teens aren’t moving nearly as much as they should be.

According to the World Health Organization, children and teens age 17 and under should get at least an hour of moderate-to-vigorous physical activity every day. But researchers found that a significant number of kids age 11 and under fell short of that goal — more than 25 percent of boys and a whopping 50 percent of girls.

Zipunnikov says that we need to start thinking about how to “modify daily schedules, in schools for example, to be more conducive to increasing physical activity.”

Not everyone is just sitting around, though. Upticks were seen among 20-somethings and early 30-somethings (maybe millennials aren’t so lazy after all!).

But, sadly, it’s all downhill after age 35: activity levels declined permanently after that marker.