The prevalence of overweight and obesity is increasing among children and adolescents, and this is linked to the emergence of type 2 diabetes in young people. There is evidence implicating physical inactivity in the development of overweight and obesity in young people and supporting a role for increased physical activity and reduced sedentary behavior in the management of overweight and obesity. However, this evidence is not strong, as few randomized controlled trials have been conducted. The same is true of evidence linking physical inactivity with type 2 diabetes, CVD, bone health, self-esteem, cognitive function, anxiety, and depression. In all of these areas, randomized controlled trials are required to strengthen the evidence base. Ideally, these trials would involve large sample sizes and long follow-up periods. Despite the limitations, however, there is suffi cient evidence from robust observational studies to support a role for physical activity in optimizing physical and mental health in young people.
Available evidence supports a role for physical activity in enhancing many aspects of physical and mental health in young people. Physical activity may reduce the likelihood of overweight and obesity, type 2 diabetes, CVD, anxiety, and depression in children and adolescents as well as enhance their cognitive function, self-esteem, and bone health. It should be recognized that there are limitations to the evidence linking physical activity to health in young people, and it does not always follow that physical activity will be benefi cial. Moreover, an overemphasis on physical activity in young people may have detrimental eff ects, such as an increased prevalence of underweight in obesity prevention programs. Despite these caveats, young people should engage in 1 h or more of physical activity daily for optimal physical and mental development. This activity may take a variety of forms, including unsupervised play, active transportation, and structured activities (e.g., exercise, physical education, sport).