In their adolescent years, young adults are expected to be nearing peak physical shape. Yet a new study of more than 12,000 Americans found teenagers are often just as sedentary as senior citizens, according to The Washington Post.
The study, published in Preventive Medicine, involved 12,529 Americans ages 6 to 85 and examined how physical activity changes over a lifetime. Participants wore accelerometers, or devices that measure movement, for seven consecutive days. Researchers included all types of movement, not just strenuous exercise, in their analysis.
Researchers found that physical activity is most commonly at its highest at age 6. Young children's characteristic squirminess makes this an expected finding. But what researchers didn't expect was to discover a drastic decline in physical activity through the teenage years. By age 19, the average American is as physically active as a 60-year-old, according to the report.
"At 60-plus, many people have health issues that might cause a restriction in movement, but why is this happening at age 19? It suggests that the social structures in place may not be supporting physical activity," Vijay Varma, PhD, a researcher at the National Institute on Aging and lead author of the study, told The Washington Post.
Dr. Varma hypothesized that the modern school day, which includes long stretches of sitting, may be partially responsible. Another big factor could be too much screen time, including time spent watching TV or using a laptop, tablet or phone. Some studies have found Americans spend as many as seven to nine hours per day staring at a screen, and consequently, being physically inactive.