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Brief interruption of sedentary behavior improves blood glucose in children

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August 27, 2015

Children’s blood glucose levels could be improved by simply taking short breaks to walk during sedentary activities, according to recent study findings published in The Journal of Clinical Endocrinology & Metabolism.

“Interrupting a long period of sitting with a few minutes of moderate activity can have short-term benefits on a child’s metabolism,” Jack A. Yanovski, MD, PhD, of the NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, said in a press release. “While we know getting 30 minutes or more of moderate-intensity exercise each day improves children’s health and metabolism, small behavioral changes like taking short walking breaks can also yield some benefits.”

Jack Yanovski

Jack A. Yanovski

Yanovski and colleagues evaluated 28 children aged 7 to 11 years with normal weight to determine whether glucose tolerance could be improved by interrupting sitting with short, moderate-intensity walking bouts. In a random order and on different days, participants underwent one of two conditions: continuous sitting for 3 hours (SIT) or sitting interrupted by walking (3 minutes of moderate-intensity walking every 30 minutes; SIT+WALK). An oral glucose tolerance test was used to measure insulin, C-peptide, glucose and free fatty acids every 30 minutes for 3 hours. Hormone and substrate measurements were used to calculate area under the curve (AUC).

Mean heart rate, wrist-mounted triaxial vector sum magnitude, hip-mounted triaxial vector sum magnitude and step counts during the 3 hours were higher during the SIT+WALK condition compared with the SIT condition during OGTT (P < .001 for all).

Compared with the SIT condition, the SIT+WALK condition revealed lower insulin secretion (P = .036). At all of the time points during the SIT+WALK condition, post-drink mean insulin concentrations were lower except at 0 minutes (P < .02). Compared with the SIT condition, mean insulin AUC was 32% lower in the SIT+WALK condition (P < .001).

There were lower insulin levels (P = .036) and free fatty acid concentrations (P = .009) in the SIT+WALK condition compared with the SIT condition.

“Sustained sedentary behavior after a meal diminishes the muscles’ ability to help clear sugar from the bloodstream,” study researcher Britni R. Belcher, PhD, MPH, of the National Cancer Institute, said in the 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.” – by Amber Cox

Disclosure: Yanovski reports being a commissioned officer in the U.S. Public Health Service. Belcher reports receiving a postdoctoral training award from the National Cancer Institute Cancer Prevention Fellowship Program in the Division of Cancer Prevention. Please see the full study for a list of all other authors’ relevant financial disclosures.

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Bethany Barone Gibbs

Bethany Barone Gibbs

This well designed study demonstrates that breaking up sitting with a 3-minute walk every 30 minutes, as compared to continuous sitting, improves the ability of the body to metabolize glucose over 3 hours in normal weight, healthy children.  Similar studies have demonstrated the same effect in adults.  To build on these results, we still don't understand if breaking up sitting in this way will have long-term and not just acute effects on cardiometabolic health, so longer intervention studies are needed.  Also, we need to figure out how to decrease sitting and break up sitting in the real world for kids who have plenty of mandatory (car and bus riding, school and studying) and discretionary (television, video games, leisure reading) prolonged sitting activities.  The potential implications of these findings are that building in activity breaks from prolonged sedentary behavior should be a goal for parents, caretakers, teachers, and kids.

Bethany Barone Gibbs, PhD
Assistant Professor
Department of Health and Physical Activity, University of Pittsburgh

Disclosure: Barone Gibbs reports being principal investigator on a grant from HumanScale.