Interrupting sedentary behavior with short periods of moderate-intensity walking could protect children from diabetes, cardiovascular disease, and cancer, according to researchers.

“We know that 30 minutes or more of moderate physical activity benefits children’s health,” study researcher Jack Yanovski, MD, of the National Institute of Child Health and Human Development (NICHD), said during a press 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.”

Sedentary behaviors, like watching television, are linked to lower fruit and vegetable consumption, higher fast food consumption, and may be associated with obesity and insulin resistance. Children in the United States spend roughly 6 hours per day in a sedentary position, and these behaviors are consistent from childhood through adolescence, according to background information in the study. 


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Previous research in adult populations suggests that interrupting sedentary behaviors can improve metabolic parameters and reduce cardiometabolic risk. To determine if the same tactic could improve glucose tolerance in children, Yanovic and colleagues tested the strategy in 28 normal weight children aged 7 to 11 years. 

The study findings, published in the Journal of Clinical Endocrinology and Metabolism, showed that children who walked for 3 minutes every 30 minutes to interrupt sedentary behavior had lower blood glucose, free fatty acid concentrations, and insulin levels.

During two experimental visits at the National Institutes of Health Hatfield Clinical Research Center, participants were randomly assigned to 1 of the following 2 conditions. In the first condition, the participants sat continuously for 3 hours, watching movies, coloring, or doing homework, with limited movement. In the second condition, the children walked on a treadmill for three minutes every 30 minutes. The speed of the treadmill was adjusted to maintain the participant’s target heart rate. 

The children were asked to return 30 days later, and the 2 conditions were switched: children who had sat continuously during the first session sat for an additional 3 hours with interrupted walking, and the group that participated in interrupted walking remained sedentary.

To record the results, participants consumed a dextrose oral solution, and blood samples were drawn every 30 minutes for 3 hours to test how quickly participants absorbed glucose and produced insulin. The children were also given a buffet meal for lunch consisting of macronutrients (12% protein, 51% carbohydrate, and 37% fat) and of foods frequently consumed by children. There was no difference in food intake when the children remained sedentary for 3 hours vs the interrupted walking condition (975 vs 963 kcal; P = .85).

After sedentary interruption, children’s blood glucose levels were 7% lower (P = .018) than when they remained sitting for the full three hours, C-peptides were 17% lower (< .001), and insulin levels were 32% lower (P < .001), the researchers found. 

If additional long-term studies confirm these results, interrupted bouts of physical activity during long periods of sedentary behavior could reduce cardiometabolic risk in children, the researchers concluded. They called for additional research to explore how patterns of sedentary behavior may cause negative health effects in children, and how these might be prevented with short periods of walking.

Reference

  1. Belcher B, Berrigan D, Papachristopoulou A, Brady SM et al. Effects of Interrupting Children’s Sedentary Behaviors With Activity on Metabolic Function: A Randomized Trial. J Clin Endocr Metab. 2015;doi:10.1210/jc.2015-2803.