• Sedentary behaviors such as sitting and television viewing contribute to health risks both because of and independently of their impact on physical activity.
• Health-related behaviors and disease risk factors track from childhood to adulthood, indicating that early and ongoing opportunities for physical activity are needed for maximum health benefit.
• To be effective, physical activity programming must align with the predictable developmental changes in children’s exercise capacity and motor skills, which affect the activities in which they can successfully engage.
• Frequent bouts of physical activity throughout the day yield short-term benefits for mental and cognitive health while also providing opportunities to practice skills and building confidence that promotes ongoing engagement in physical activity.
• Distinct types of physical activity address unique health concerns and contribute in distinct ways to children’s health, suggesting that a varied regimen including aerobic and resistance exercise, structured and unstructured opportunities, and both longer sessions and shorter bouts will likely confer the greatest benefit.
The behaviors and traits of today’s children, along with their genetics, are determinants of their growth and development; their physical, mental, and psychosocial health; and their physical, cognitive, and academic performance. Technological advances of modern society have contributed to a sedentary lifestyle that has changed the phenotype of children from that of 20 years ago. Children today weigh more and have a higher body mass index (BMI) than their peers of just a generation earlier (Ogden et al., 2012). Behaviorally, most children fail to engage in vigorous- or moderate-intensity physical activity for the recommended 60 minutes or more each day, with as many as one-third reporting no physical activity in the preceding 5 days (CDC, 2012). This lack of participation in physical activity has contributed to a greater prevalence of pediatric obesity, a decrease in fitness (e.g., flexibility, muscular strength, cardiorespiratory capacity), and a greater risk for disease (Boreham and Riddoch, 2001; Eisenmann, 2003; Malina, 2007; Steele et al., 2008). (See Box 3-1 for an overview of the relationship between physical activity and physical fitness.)