Ah, to be young, fit, and active.

Or, more accurately: Ah, to be young and sedentary—as new research from Johns Hopkins Bloomberg School of Public Health suggests.

That's the trend among young adults in America, according to the a study published in the journal Preventive Medicine, which found that children and teens in the United States move almost as often as senior citizens.

"By age 19, [the survey participants] were comparable to 60-year-olds," said lead study author Vadim Zipunnikov in a press release. "For school-age children, the primary window for activity was the afternoon between 2 and 6 p.m. So the big question is: How do we modify daily schedules, in schools for example, to be more conducive to increasing physical activity?"

In the study, researchers pooled data from the 2003-2004 and 2005-2006 cycles of the National Health and Nutrition Examination Survey. The survey encompassed 12,529 participants who wore wearable fitness trackers for one full week, removing them only to bathe and sleep. The wearables tracked how much time participants were inactive, moving a little, or exercising hard. The participants were broken up into five age groups: children (ages six to 11); adolescents (ages 12 to 19); young adults (ages 20 to 29); adults at midlife (ages 31 to 59); and older adults (age 60 through age 84). Nearly half were male, half female.

For the most part, males were more active than females, especially when it came to high-intensity activity. But after midlife, the numbers flipped: Older men were more sedentary and did less light-intensity exercise than women, the researchers found.

And while American teens may be suffering from an epidemic of couchlock, not all the trendlines are so bad: Young adults over the age of 20 exhibited an increase in activity that blossomed until they turned 35, after which activity plummeted through midlife and older adulthood, the researchers say. What’s more, twentysomethings were active throughout the day, with a boom in activity early in the morning (compared to younger adolescents).

"The goal of campaigns aimed at increasing physical activity has focused on increasing higher-intensity exercise," says Zipunnikov. "Our study suggests that these efforts should consider time of day, and also focus on increasing lower-intensity physical activity and reducing inactivity."

Our suggestion? Do activities and sports you love, like these 10 ways to burn 1,000 calories without realizing it, these eight fat-burning water sports, or the six greatest fat-torching outdoor sports of all time.