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Couch potato kids can avoid obesity reports new study

Robin Wulffson MD's picture
child obesity, sedentary activity, exercise, TV watching, video games

The current obesity epidemic also includes children in the United States. Many anti-obesity campaigns include restrictions on sedentary activities such as TV-watching and playing video games. The campaigns also note the current Centers for Disease Control and Prevention (CDC) guidelines for exercise, which stress that children should exercise for 60 or more minutes per day and that aerobic activity should make up most of that time. A new study conducted by researchers at Northwestern University in Chicago and Iowa University attempted to determine which contributes more to child obesity: significant sedentary activity or low levels of moderate through vigorous activity. The published the results of their study, The Iowa Bone Development Study, online on January 10 in the Journal of Pediatrics.

The study group comprised 277 boys and 277 girls (95% Caucasian; two-thirds of parents with college graduation or higher education). From 2000 through 2009, the children underwent body fat and accelerometry measurement at examinations of 8, 11, 13, and/or 15 years of age (during 2000-2009). Accelerometry is a method of objectively monitoring human movements, and has many applications including the measurement of physical activity levels as well as the identification and classification of movements performed by subjects. The main exposure was accelerometry-measured sedentary time, frequency of breaks in sedentary time, and moderate- to vigorous-intensity physical activity time. The primary outcome measurement was dual energy X-ray absorptiometry-measured body fat mass.

The researchers found that, adjusted for age, height, physical maturity, and sedentary time, growth models showed that high moderate-to-vigorous physical activity time was associated with low body fat mass in both boys and girls. However, sedentary time and frequency of breaks in sedentary time were not associated with body fat mass.

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The authors stress that their study does not support an independent effect of sedentarism on adiposity. They noted that the preventive effect of moderate- to vigorous-intensity physical activity on adiposity in children and adolescents remained strong after adjusting for the effect of sedentarism.

Take home message:
The results of this study differ from similar studies in adults, which note that adult sedentary activity (i.e., excessive TV watching) increase the risk of obesity and premature death. With the ubiquitous presence of video games and TV programming, it is impossible to forbid these activities for your children. However, reasonable restrictions should be made and parents must insure that children get the recommended amount of daily exercise. It would be prudent to check if your child’s school has an adequate exercise program. When children are not in school, parents should determine that their children are exercising at an adequate level either with sports program or neighborhood activities.

The CDC guidelines for children:

  • Aerobic Activity: Aerobic activity should make up most of your child's 60 or more minutes of physical activity each day. This can include either moderate-intensity aerobic activity, such as brisk walking, or vigorous-intensity activity, such as running. Be sure to include vigorous-intensity aerobic activity on at least three days per week.
  • Muscle Strengthening: Include muscle strengthening activities, such as gymnastics or push-ups, at least three days per week as part of your child's 60 or more minutes.
  • Bone Strengthening: Include bone strengthening activities, such as jumping rope or running, at least three days per week as part of your child's 60 or more minutes.

Reference: Journal of Pediatrics

See also:
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