Even brief spurts of exercise may benefit children, researchers report.
Their study of 28 healthy, normal-weight children found that doing three minutes of moderate-intensity walking every half hour over three hours of sitting led to lower levels of blood sugar and insulin, compared to another day when the children sat for three hours straight.
Moderate physical activity
On the day the children took brief walks, they did not eat any more at lunch than on the day they remained seated for the entire three hours, according to the study published online in the Journal of Clinical Endocrinology and Metabolism.
The findings suggest that brief bouts of activity during otherwise inactive periods could help protect children against type 2 diabetes, heart disease and cancer, the U.S. National Institutes of Health researchers said.
"We know that 30 minutes or more of moderate physical activity benefits children's health," study senior author Dr Jack Yanovski, chief of the section on growth and obesity at the U.S. National Institute of Child Health and Human Development, said in a government news release.
"It can be difficult to fit longer stretches of physical activity into the day. Our study indicates that even small activity breaks could have a substantial impact on children's long-term health," he added.
Clearing sugar from the bloodstream
American children spend about six hours a day either sitting or reclining, the researchers said. Previous studies have linked such inactivity to obesity and insulin resistance, a risk factor for type 2 diabetes, the researchers explained.
"Sustained sedentary behaviour after a meal diminishes the muscles' ability to help clear sugar from the bloodstream," study first author Britni Belcher, a cancer prevention fellow at the U.S. National Cancer Institute and an assistant professor at the University of Southern California, said in the news release.
"That forces the body to produce more insulin, which may increase the risk for beta cell dysfunction that can lead to the onset of type 2 diabetes. Our findings suggest even short activity breaks can help overcome these negative effects, at least in the short term," Belcher explained.
More than one-third of American children and teens are overweight or obese, which increases their risk for heart disease, type 2 diabetes, stroke and cancer.