By Natasha Persaud

Does your child sit for hours at school, then plop on the couch at home? If so, don't worry too much. As long as she is reasonably active during the day, she is probably reaping health benefits, suggests a JAMA analysis.

Researchers examined 14 studies involving nearly 21,000 school-age children and teens in more than 4 countries to gauge the potential harmful effects of sedentary time. In these studies, kids wore accelerometers to record their motions while sitting, playing and going about their daily routine.

Compared to children with the lowest activity levels, kids who were most active—playing for 35 minutes a day at moderate to vigorous intensity—had healthier profiles, including healthier waist circumference, blood pressure, and insulin, triglyceride, and HDL cholesterol levels. By contrast, time spent sitting appeared to have no effect on these measures, except for waist size. The majority of study participants were of normal weight to start; only 18 percent were considered overweight and 7 percent were obese.

To improve their health, kids with the lowest activity levels would require an extra 20 minutes or more of intense play, suggest the researchers. In general, children and teens should be getting at least 60 minutes of moderate to vigorous physical activity daily, according to public health experts. Participating in activities such as brisk walking, jogging, cycling or playing soccer and other team sports can help them meet that goal.

Decreasing TV time may still be an important goal, according to the researchers, as watching TV has been linked to unhealthy snacking and soda consumption.


Ekelund, et al. Moderate to vigorous physical activity and sedentary time and cardiometabolic risk factors in children and adolescents. JAMA. 2012 Feb 15;307(7):704-12.

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Publication Review By: the Editorial Staff at

Published: 05 Mar 2012

Last Modified: 18 Sep 2015