More activity may mean healthier kids, despite sedentary time

Spending more time being active may improve blood pressure, blood sugar, cholesterol and reduce waist circumference for children regardless of how much time they spend sedentary, a study finds.

Researchers reviewed 14 studies that included 20,871 children age 4 to 18 and analyzed data on how much time they spent sedentary, how much they spent in moderate to vigorous physical activity, and health measures such as waist circumference, blood pressure, trigylcerides, HDL cholesterol and insulin.

Among the children, 74.9% were considered normal weight, 17.7% were overweight, and 7.4% were obese. Overall boys were substantially more active than girls.

The more moderate to vigorous activity the kids got, the better their health outcomes, such as smaller waist circumferences and lower levels of blood pressure and triglycerides, despite the amount of time they spent sedentary.

Those in the top third of activity levels got more than 35 minutes a day of exercise, while those in the lower third got less than 18 minutes a day. A 10-minute difference in exercise time was linked with a waist circumference difference of about 0.5 cm.

The authors wrote that although children should be encouraged to spend more time active, the time they spend sedentary shouldn’t be ignored. “Decreasing TV time in youth may still be an important public health goal as TV viewing may be associated with other unhealthy behaviors such as snacking and soft drink consumption,” they said. “TV viewing is also associated with exposure to advertisements that often promote unhealthy dietary habits.”

The study was published in the Feb. 15 issue of the Journal of the American Medical Assn.