THURSDAY, Sept. 27 (HealthDay News) -- Formal physical exercise
programs for children have only a small impact on overall activity
and thus on weight loss, British researchers report.
Their study raises questions about the best ways to help
children attain or maintain a healthy weight.
"Physical activity interventions are not increasing physical activity sufficiently to impact on the body mass or body fat of children," said lead researcher Brad Metcalf, of the department of endocrinology and metabolism at Peninsula College of Medicine and Dentistry in Plymouth, England. "It is in everyone's interest to find something that works effectively," he added.
But other experts said instead of dismissing organized
interventions as ineffective, policymakers should conclude that
still more is needed to stem childhood obesity. In the United
States, about 17 percent of children aged 2 years and older are
"I disagree that the importance of physical activity to childhood obesity control, or health promotion, has been called into question by this study," said Dr. David Katz, director of the Yale University Prevention Research Center in New Haven, Conn.
On the contrary, "we have cause to question if we are doing
enough to make routine activity the cultural norm, so that such
programming can achieve greater effects," Katz said. "An
intervention, no matter how good, can only achieve so much if not
surrounded by cultural supports."
Katz also faulted the study for not including data from the many
studies that show a significant benefit from exercise.
For the study, published in the Sept. 27 online edition of the
BMJ, the researchers analyzed 30 studies conducted between
1990 and 2012 involving children aged 16 and under.
This type of study, known as a meta-analysis, is used to find
common threads running through multiple studies. Problems with this
type of analysis can arise from the weakness of any of the studies
included and the difficulty of combining disparate data.
Unlike some other studies of children's activity, these studies
measured actual movement during children's waking hours using
accelerometers and didn't rely on questionnaires.
Eight of the 30 studies included only overweight or obese
children. One U.S. study followed more than 700 children, average
age 11, taking part in 90 minutes of after-school physical activity
three times a week. Another involved more than 250 Scottish nursery
school children who did 30 minutes of physical activity three times
Overall, the researchers said the programs achieved
"small-to-negligible" increases in children's total activity with
small improvements in time spent in moderate or vigorous
intensities -- about four minutes' walking or running per day.
This could have only a minimal effect on weight, they
"It's been shown by others that four minutes extra walking/running is only associated with a 2 millimeter difference in waist circumference," Metcalf said. While the added activity sessions might offer other benefits, including better coordination, improved ability at a sport, team participation and genuine enjoyment, they won't "have a meaningful impact on obesity prevention," he said.
These programs may not work because they might replace
physically demanding after-school activities that take place
outdoors and last for longer periods, the researchers said. It's
also possible that children eat more after these sessions, they
Mark Hamer, from the department of epidemiology and public
health at University College London and co-author of an
accompanying journal editorial, said the study has limitations but
"provides the best evidence to date on the effectiveness of
physical activity interventions in childhood."
Better approaches to increasing children's physical activity are
needed, Hamer said. Perhaps physical changes to the indoor and
outdoor environment can facilitate activity, he suggested.
He and others maintain that a wealth of evidence supports the
association between an active lifestyle and better health.
Samantha Heller, exercise physiologist and clinical nutrition
coordinator at the Center for Cancer Care at Griffin Hospital in
Derby, Conn., pointed out that programs that aim to boost
children's activity levels may not influence sedentary behavior at
home or once the programs conclude.
Also, "many interventions do not include a nutrition component
that could impact food choices, overall nutrition or calorie
intake," she said.
School environments need to shift toward a more active day for
kids, Heller said. "We need to continue to develop programs,
environments and classes that encourage and educate children and
teens on the importance of exercise and physical activity in ways
that are meaningful and fun for them," she added.
For more information on childhood obesity, visit the
U.S. Centers for Disease Control and
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