The kids aren't alright when it comes to staying active. That's according to a new study, which found that kids' and teens' physical activity levels are lower than previously thought. People in the final year of their teens were especially disappointing on the activity front: "Activity levels at the end of adolescence were alarmingly low, and by age 19, they were comparable to 60-year-olds," Vadim Zipunnikov, the study's senior author, said in a statement.
The study also showed that only people over the age of 20 increased their physical activity levels—but that progress stopped at age 35, when physical activity declined. Overall, it's a pretty bleak picture, describing sedentary kids and teens whose lack of exercise may be a contributing factor in the obesity epidemic. (Not to mention adults peaking at 35.)
Researchers from the Johns Hopkins Bloomberg School of Public Health used data from the National Health and Nutrition Examination Survey, in which 12,529 people wore fitness trackers for a week, removing them only for showering and sleeping. The devices monitored how much time they spent being sedentary or participating in light or moderate-to-vigorous physical activity. (The data is from the 2003-2004 and 2005-2006 survey cycles.)
The participants were sliced into five age groups, starting with children (ages six to 11) and adolescents (ages 12 to 19). Ages 20 to 29 were classified as "young adults," followed by adults at midlife (ages 31 to 59), and older adults (age 60 through age 84). Forty-nine percent of the participants were male, the rest were female. The results showed that children and teens were woefully inactive. For children ages five to 17, the World Health Organization (WHO) recommends at least 60 minutes of moderate-to-vigorous physical activity daily. Among the study participants, more than 25 percent of boys and 50 percent of girls ages six to 11 failed to meet that recommendation. It got worse among adolescents: From ages 12 to 19, more than 50 percent of male and 75 percent of female participants didn't hit that goal.
Zipunnikov, an assistant professor of biostatistics at the Bloomberg School, suggests trying to tweak school schedules to help children and adolescents be more active. "For school-age children, the primary window for activity was the afternoon between 2 and 6 pm," Zipunnikov said. "So the big question is how do we modify daily schedules, in schools for example, to be more conducive to increasing physical activity?" It's no surprise, really, that your environment affects how physically active you are.
The study found that men were generally more active than women across all age groups, especially with high-intensity activities. After midlife, though, their levels dropped off more sharply than among women. Among adults 60 and older, men were more sedentary and had lower light-intensity activity levels than women. It was only among 20-somethings the activity levels increased. They were active throughout the day, and were more active in the early morning than their younger peers. Researchers suggest that could be the effect of starting full-time jobs, although sitting at a desk all day does no favors for your body.
Whatever the ultimate causes, the study found 19-year-olds were as sedentary as 60-year-olds, children and teens aren't getting nearly enough exercise, and that physical activity only declines after age 35. The researchers note that while the WHO recommendations focus on moderate-to-vigorous activity, evidence shows that even low-intensity activity—just getting off the couch—has benefits.
"The goal of campaigns aimed at increasing physical activity has focused on increasing higher-intensity exercise," Zipunnikov said. "Our study suggests that these efforts should consider time of day and also focus on increasing lower-intensity physical activity and reducing inactivity." In this case, something is literally better than nothing.
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