Regular physical activity is essential for optimal growth, development and health in children.

The Physical Activity Guidelines for Americans, first published in 2008, recommend that all children and adolescents should do at least one hour of physical activity each day. Most of this time should be spent in moderate- or vigorous-intensity aerobic physical activity.

Additionally, children should include muscle and bone-strengthening activity at least three days a week as part of the 60 or more minutes per day.

These activities should be appropriate for their age, be enjoyable and offer variety.

In younger children, active play that involves running, jumping and climbing meets the call for aerobic, as well as muscle and bone-strengthening, activity.

Older kids can get these types of exercise through sports, physical education in school or other active pursuits.

Unfortunately, most kids don’t meet these recommendations. According to 2011 survey, only about 30 percent of high school students participated in at least 60 minutes per day of physical activity during the week prior to the survey. That means that less than a third of high school students meet the recommendation!

Worse, 14 percent of high school students did not participate in 60 or more minutes of physical activity on any day in the week leading up to the survey.

A different survey showed that only 42 percent of younger children participated in at least 60 minutes of moderate or vigorous activity on most days of the past week. This is surprising considering that, for younger children, pretty much anything that involves being active counts!

So why aren’t kids getting enough activity? As much as it would be nice to blame television and video games, this isn’t the only problem.

While it is true that many kids spend nearly as much time sitting in front of a computer or TV screen as they do in school, the real issue is that adults, including parents and educators, don’t encourage participation in activity.

Almost all elementary, middle and high school-age children are in school for at least six hours per day, yet less than 10 percent have access to daily physical education.

Other opportunities, including activity breaks during and between classes, recess and active transportation to and from school, are limited. In fact, in an effort to dedicate more time for test preparation, PE and other activities are among the first to be cut.

At home, parental example and encouragement are important determinants for children’s activity. Active parents are likely to have kids who are active, and this lifestyle tends to persist through adolescence and into adulthood. Kids who are encouraged by their parents to play sports or engage in active play or other activities are 65 percent more likely to do so. Considering that less than half of U.S. adults are active on a daily basis, this positive influence may be missing.

What can we do to promote activity in children in our community? First, most of us could stand to be more active ourselves, so we should start by modeling good activity habits and include our children and grandchildren. Going for a walk in the neighborhood, to the playground or to do yard work is a good start. Second, we should demand that kids be provided with opportunities for activity in school. Not only is it good for their health, but children who are active in school tend to learn more and do better on tests. Third, we should limit sedentary pursuits, such as video games or watching TV, and encourage kids to do something active.

Brian Parr, Ph.D., is an associate professor in the Department of Exercise and Sports Science at USC Aiken where he teaches courses in exercise physiology, nutrition and health behavior.