Short bouts of moderate walking has been shown to offset the impact of a lack of sustained exercise in children and protect against diseases related to obesity and inactivity, according to new research from the National Institutes of Health.

The study, “Effects of Interrupting Children’s Sedentary Behaviours with Activity on Metabolic Function: A Randomized Trial”, found that children who interrupted periods of sitting with three minutes of moderate intensity walking every half hour, had lower levels of blood glucose and insulin compared to periods when they remained seated for three hours.

The researchers enrolled 28 healthy, normal-weight children for two visits. They were randomly assigned to two groups. Children in the first group remained seated for three hours and either watched television, read or engaged in other sedentary activities. Children in the second grop alternated sitting with three minutes of moderate-intensity walking on a treadmill for every 30 minutes of the three our period. Each of the children returned to the centre seven to 30 days later and were switched to the other group.

During the session they were given an oral glucose tolerance test to see how rapidly their bodies absorb glucose and how much insulin they produce.

On the days they walked, the blood glucose levels were, on average, 7 per cent lower than on the days they were sedentary and their insulin levels were 32 per cent lower.

Also blood levels of free fatty acids – high levels of which are linked to type 2 diabetes – were lower. As were levels of C-peptide, an indicator of how hard the pancreas is working to control blood sugar.

After the sessions the children were allowed to choose their lunch from a buffet and the walking sessions did not appear to stimulate the children to eat more than usual.

“We know that 30 minutes or more of moderate physical activity benefits children’s health,” said the study’s senior author, Jack A. Yanovski, chief of NICHD’s Section on Growth and Obesity. “It can be difficult to fit longer stretches of physical activity into one day. Our study indicates that even small activity breaks could have a substantial impact on children’s long-term health.”

Children in the US frequently remain sedentary for up to six hours a day and Dr Yanovski says that future studies are needed to examine if working such breaks into school class time could be part of effective strategies to prevent obesity-related illness.