Today's teens have more in common with 60-year-olds — and not in a good way — than you might think. A disturbing study finds teens are only about as active as the average 60-year-old. And while they become slightly more active in their 20s and 30s, once they reach 35, their activity decreases for the rest of their lives.
The study did not track people as they grew older. Instead it looked at one week in the life of over 12,000 people in the United States, participants in the National Health and Nutrition Examination Survey (NHANES). All wore activity tracking devices continuously, except when bathing and at bedtime, so their activity was actually measured, not self-reported. The amounts of physical activity engaged in by different age groups were then compared. Many differences were found.
The study found that physical activity levels dropped sharply as children's age rose from six to 19, partially because their morning activity started later and later as they got older.
More than 25 percent of boys and 50 percent of girls between six and 11 in the study did not meet basic fitness guidelines. And these percentages were worse for adolescents.
These changes are experienced differently by men and women. For most age groups, women's activity is less than men's. But men show a sharper activity decline as they age than women do, so that, by age 60, this relationship has reversed: men 60 and over are less active than women.
It's among younger people that the results were the most striking. The World Health Organization recommends at least 60 minutes of moderate-to-vigorous physical activity a day for children age 5 to 17. More than 25 percent of boys and 50 percent of girls between six and 11 in the study did not meet these guidelines. And these percentages were worse for adolescents, with 50 percent of the boys and 75 percent of the girls aged 12 to 19 not meeting these exercise guidelines.
The activity trackers revealed that certain age groups were most and least active at particular times of day. This means there may be specific windows of opportunity for raising activity. For school-age children, this window seems to be between two and six in the afternoon.
The World Health Organization and other organizations usually frame their activity guidelines in terms of moderate-to-vigorous activity and that is also what many public health campaigns seek to increase. But there is now a growing consensus on the benefits of taking a different approach — with a little exercise being a lot better than no exercise at all.
Between the sedentary allure of the digital world and cuts to school recess and physical education programs, it is not surprising that teens and 20-somethings are less active than they were a generation earlier. And many 60-somethings are probably more active than their parents' generation. Maybe 19-year-olds could start working out with mom and dad.
The study appears in Preventive Medicine.