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.

The researchers broke down findings 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). Forty-nine percent were male.

Rise in obesity fuels concerns

The findings, which were published online recently in the journal Preventive Medicine, come amid heightened concerns that lack of exercise is contributing to the growing obesity epidemic, particularly among children and teens.

The finding that physical activity among people at the end of adolescence match those with people 40 years older provides strong evidence that childhood and adolescence represents a high-risk time period for physical inactivity, the researchers say.

While lower physical activity among older adults may be partially related to physiologic changes, including physical and cognitive impairments, lower levels of physical activity among children and adolescents generally are not driven by factors related to impaired mobility.

Move every day

Teens should try to fit in some physical activity every day to lessen their chances of developing chronic illness as adults, says family nurse practitioner Jennifer Brubaker, PhD, FNP-BC, of Cleveland Clinic Children’s.

Obesity has been linked to several serious chronic adulthood illnesses such as heart disease, stroke, diabetes and cancer. More than 12 million U.S. children and teenagers are considered to be obese, says the U.S. Centers for Disease Control and Prevention (CDC).

“Ideally, children and teens should be getting at least 60 minutes a day of physical activity,” Ms. Brubaker says.

What parents can do

Too much screen time can be a barrier for adolescents to get enough movement in their day.

“Set healthy limits for screen time by making sure your kids aren’t sitting around all day long on their screens,” Ms. Brubaker says.“Try to encourage them, in any way you can, to get outside and do more activities.

“They should focus on increasing the intensity of their physical activity,” she says. “They’ll know that they are at the right level of exertion when they are sweating and getting winded.””

One of the best ways to combat the obesity trend is to get the whole family involved in physical activity, Ms. Brubaker says.

“They should really try to increase the intensity of their physical activity,” she says. “They’ll know that they are at the right level of exertion when they are sweating and getting winded.”

Teaching children to be active and eat healthy will make it more likely that they will be able to continue those good habits into adulthood, Ms. Brubaker says.

Complete results of the study can be found in the journal Preventive Medicine.


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