Type of Activity
Because the Guidelines apply to children and adolescents, they must be flexible to include types of activities appropriate for this wide age range of school-age youth. To meet the Guidelines, youth can participate in either unstructured (e.g., unorganized playground games) or structured (e.g., organized sports) physical activities. As children age, structured activity often becomes a more preferred way to be physically active.
Muscle- and bone-strengthening activities are recommended for children and adolescents on at least 3 days of the week. Muscle-strengthening activities include playing games such as tug-of-war, doing calisthenics such as push-ups or sit-ups, or doing resistance exercises using one’s own body weight, resistance bands, or weights. Bone-strengthening activities include jumping activities like jumping rope or games or sports that involve jumping, like gymnastics, basketball, or volleyball. Some activities (e.g., gymnastics) serve dual purposes and may help build strong muscles and bones.
There is strong scientific evidence that a combination of moderate- and vigorous-intensity physical activity improves the cardiorespiratory fitness of school-age youth (USDHHS, 2008). The guidelines for children and adolescents, therefore, require some participation in vigorous-intensity activity—participation in moderate-intensity activity only is not sufficient for youth. Again, the exact amount of vigorous-intensity activity needed could not be ascertained from the available scientific evidence, but it is recommended that children and adolescents participate in vigorous-intensity activity on at least 3 days of the week.
Ensuring Age Appropriateness and Enjoyability
It is imperative that children and adolescents are encouraged to participate in a variety of activities that reflect their developmental stage and are also enjoyable—the latter being key to participation. Participation in a variety of activities allows youth to build a diverse set of skills and reduce the risk of overuse injuries. For children and adolescents, having fun is the critical factor in long-term adherence to physical activity.
Tracking the Guidelines for Youth
One ongoing surveillance system in the United States, the Youth Risk Behavior Surveillance System (YRBSS), is able to track students in grades 9 to 12 who achieve 60 minutes of moderate- to vigorous-intensity daily physical activity. Current U.S. surveillance systems for youth physical activity (to include the YRBSS and NHANES) are unable to track the number of youth who participate in muscle-strengthening or bone-strengthening activities on at least 3 days of the week. Current surveillance systems will need substantial modification to comprehensively assess the physical activity guidelines in U.S. children and adolescents.