September 21, 2015

Brief Activity Breaks May Benefit Children’s Health

At a Glance

  • Interrupting sitting time with brief bouts of walking improved metabolic function in healthy, normal-weight children.
  • The preliminary findings suggest that breaking up sedentary time may offer a strategy to reduce certain health risks in children.
Young students running down a hall Children often spend hours sitting at their school desks, sitting at home doing homework, and sitting in front of the TV or computer. Getting more active can bring many health benefits.Wavebreakmedia/iStock/Thinkstock

Children spend about 6 hours a day either seated or in a reclining position. Such sedentary behaviors have been associated with obesity and insulin resistance. Recent findings suggest that interrupting sitting time with brief bouts of walking improves glucose metabolism in adults, but little is known about the effects in children.

A team of researchers from several NIH components set out to assess whether interrupting sitting with short, moderate-intensity walking bouts could improve glucose tolerance in children. The team enrolled 28 healthy, normal-weight 7- to 11-year-old children.

The children came to the NIH Clinical Center in Bethesda, Maryland, after an overnight fast. During one visit, they remained seated for 3 hours (except to use the bathroom) with limited movement. They watched movies, read, did homework, or engaged in other sedentary activities. On another visit, they interrupted their sitting by walking on a treadmill for 3 minutes at a moderate-intensity pace every 30 minutes. They walked 6 times for a total of 18 minutes during the 3-hour time frame. The order of the conditions (sit or sit plus walk) was randomized and took place from 1 to 4 weeks apart.

The visits were performed under carefully controlled conditions that included monitoring heart rate and activity levels. During each visit, the children drank a glucose solution at the start and then had blood samples taken periodically. This procedure, known as an oral glucose tolerance test, measures the body’s ability to use glucose and is often used to test for diabetes. Results appeared online on August 27, 2015, in the Journal of Clinical Endocrinology and Metabolism.

The researchers found that during the interrupted sitting day, the children averaged 7% lower glucose levels and 32% lower insulin levels compared to when they sat for 3 hours continuously. Their blood levels of free fatty acids (high levels of which are linked to type 2 diabetes) were also lower. So were levels of C-peptide, an indicator of how hard the pancreas is working to control blood sugar.

At the end of each visit, the children were allowed to choose their lunch from food provided on a buffet table. The researchers calculated the calorie and nutrient content of what each child ate. They found that the children consumed roughly the same amounts of calories and kinds of foods after each of the sessions. This suggested that the brief walking sessions didn't stimulate the children to eat more than they normally would.

“We know that 30 minutes or more of moderate physical activity benefits children’s health,” says senior author Dr. Jack A. Yanovski of NIH’s National Institute of Child Health and Human Development (NICHD). “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.”

The researchers note that further studies will be needed to confirm these findings and to determine if fitting such breaks into school class time could be part of effective strategies to prevent obesity-related illnesses.

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Reference: Effects of Interrupting Children's Sedentary Behaviors With Activity on Metabolic Function: A Randomized Trial. Belcher BR, Berrigan D, Papachrisotopoulou A, Brady SM, Bernstein SB, Brychta RJ, Hattenbach JD, Tigner IL Jr, Courville AB, Drinkard BE, Smith KP, Rosing DR, Wolters PL, Chen KY, Yanovski JA. J Clin Endocrinol Metab. 2015 Aug 27:jc20152803. [Epub ahead of print]. PMID: 26312582.

Funding: NIH’s National Cancer Institute (NCI), National Institute of Child Health and Human Development (NICHD), National Heart, Lung, and Blood Institute (NHLBI), National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and Clinical Center.