New York: Amid heightened concern that exercise deficits are contributing to the growing obesity epidemic, new research has found that activity levels of teenagers are comparable to 60-year-olds.

The findings, published in the journal Preventive Medicine, also showed that starting at age 35, activity levels declined through midlife and older adulthood.

The study involved 12,529 participants who wore tracking devices for seven straight days, removing them for only bathing and at bedtime.

“Activity levels at the end of adolescence were alarmingly low, and by age 19, they were comparable to 60-year-olds,” said the study’s senior author, Vadim Zipunnikov, Assistant Professor at Johns Hopkins University Bloomberg School of Public Health in Maryland, US.

The study also confirmed that recommended guidelines were not being met. For instance, the World Health Organisation (WHO) recommends at least 60 minutes of moderate-to-vigorous physical activity a day for children ages five to 17 years.

The study showed that among kids ages 6-11, 25 per cent of boys and 50 per cent of girls did not meet this recommendation. Even more teens fell short of the guidelines; 50 per cent of adolescent boys and 75 per cent of teen girls weren’t active for at least an hour a day. Because the people in the study wore activity trackers throughout the day, the data also provide useful insights into when people in different age groups were most likely to be active and sedentary.

Children in school, for example, were most active from 2 to 6pm, which could reflect the fact that they’re sitting in classrooms for most of the day until mid-afternoon. The devices measured how much time participants were sedentary or engaged in light or moderate-to-vigorous physical activity.

Zipunnikov says that a single window of activity in the late afternoon may not be ideal, and that the data suggest that spreading out activity throughout the day more evenly could help encourage more exercise among kids.

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 to 84). Forty-nine per cent of the participants were male, the rest female. Activity among 20-somethings, the only age group that saw an increase in activity levels, was spread out throughout the day, with an increase in physical activity in the early morning, compared to younger adolescents. The increase may be related to starting full-time work and other life transitions.

Overall, males tended to be more physically active than females.

But after midlife, physical activity levels in males plummeted, compared with females. In the group aged 60 years and above, males were considerably less physically active, more sedentary, and engaged in less light-intensity physical activity than females. Researchers found a spike in physical activity levels in only one age group: the 20-something-year-old adults. People in this group tended to be more active in the early morning.

Surprisingly, the study found that teenagers were at the highest risk of being physically inactive, and in their late teens, this group was likely to get as little exercise as seniors.

According to Zipunnikov, “We could start playing around with times of exercise.” School start times, especially for teens, may also play a role; kids may not be getting as much exercise because they’re not getting enough sleep and are too tired to be physically active. “One of the major contributors to low levels of physical activity in children might be that they don’t get enough sleep,” he said. The message to exercise more intensely may also be backfiring, Zipunnikov says. Instead, people might be more open to programmes that focus on encouraging exercise at certain times of the day: earlier in the day for people with job obligations, later in the morning for older people and throughout the day for children. Since the participants in the study wore activity trackers throughout the day, the data also provide useful insights into when people in different age groups were most likely to be active and sedentary.

Children in school, for example, were most active from 2 to 6pm, which could reflect the fact that they’re sitting in classrooms for most of the day. Zipunnikov said a single window of activity in the late afternoon may not be ideal, and that the data suggest that spreading out activity throughout the day more evenly could help encourage more exercise among children.

— Agencies