How Social Networks Can Push Kids to Be More Active A new study found that the single biggest influence on kids' physical activity levels was the exercise habits of their six closest friends. Martin Barraud / Getty Images Peer pressure can be a powerful force, and sometimes a positive one. For example, hanging out with active peers may lead kids to exercise more, making a child's social network a potential vehicle for promoting healthy habits and reducing obesity. That's what researchers led by Sabina Gesell, a research assistant professor in pediatrics at Vanderbilt School of Medicine, and her colleagues are reporting in the journal Pediatrics. The scientists studied networks of friends in an after-school program involving students aged 5 to 12. Using a pedometer-like device that recorded minute muscle movements, the researchers tracked kids" physical activity levels over a period of 12 weeks. At the start of the program, none of the children knew one another well, so the researchers were able to track how the youngsters" made and dropped friends, and what effect these changing relationships had on their physical activity level. Turned out, it was a big one: during the time the children spent in the program, the strongest factor influencing how much time they spent engaged in moderate to vigorous physical activity was the activity level of their four to six closest friends. In fact, children changed their exercise level about 10% to better match those in their circle; children who hung out with more active students were more likely to increase their physical activity levels, while those who befriended more sedentary children became less active. "We see evidence that the children are mirroring, emulating or adjusting to be similar to their friends," says Gesell. And that's exciting because we saw meaningful changes in activity levels in 12 weeks. The results are encouraging also because they suggest a potentially inexpensive and effective way to change children's behavior. Rather than relying only on organized exercise programs or drowning kids in messages to get moving, perhaps a subtler approach - introducing sedentary kids to more active ones - might help more kids get off the couch. From a public health perspective, that would mean seeding groups like after-school programs or community groups with children who like to exercise, so that by emulating them, others may become more active by association. Even kids in day care can stand to benefit: a recent study found that children in day care are active only about 2% to 3% of the time they are there. Gesell says the results could help in providing a much-needed new tool for confronting the obesity epidemic. (MORE: Back Off Mom. Parents Who Hover Impede Kids" Activity) Gesell is eager to conduct the next phase of studies, which would break down exactly how large an influence a single active child can have on the behavior of his more sedentary classmates. Hers is not the first study to analyze the "contagion" effect of social networks. Previous studies have documented how a person's social network can influence everything from his likelihood of gaining weight or quitting smoking to levels of loneliness and happiness. However, Gesell is the first to study the phenomenon in children. "This is a novel approach to obesity prevention," says Gesell. None of the approaches to combating obesity are really working now, and we need a new approach. The social environment does carry more power than we have given it credit for, so we should leverage that intentionally. Given that children are increasingly connected to one another, whether through face-to-face interactions or virtual ones, their social networks can clearly have a profound effect on many aspects of their behavior and well-being. Using these childhood networks to encourage exercise - and perhaps other positive behaviors - could help kids in the long run, by turning them into healthier adults.