This is an excerpt from Foundations of Physical Activity and Public Health by Harold Kohl III & Tinker Murray.
School-based physical activity programming, such as physical education (PE) and sport participation (athletics), have been part of school culture for over 100 years in the United States and many other countries. Physical educators and coaches promote exercise to youth and young adults in schools to help them achieve or improve their physical fitness and athletic performance. Since 2005, the national focus for PE and athletics in U.S. schools has shifted somewhat to promoting physical activity for all students (more so in PE) and promoting student health and safety (more so in athletics).Schools today are also looking to promote physical activity at all grade levels in school venues other than just PE and athletics. Enhanced school-based PE is a recommended strategy that works to increase physical activity (Kahn et al. 2002).
In addition to PE, schools are increasingly looking to integrate physical activity into other parts of students' lives. Current best practices include pre-kindergarten (pre-K) programs, kindergarten programs, before-school programs, classroom activity breaks, recess breaks, after-school programs, commercially sponsored programs, and summer (seasonal) programs.
Rationale for School-Based Physical Activity Programs
This chapter is based on several detailed reports (Kahn et al. 2002; Massengale 1987; Siedentop 2009) and the Guide to Community Preventive Services (Community Guide; 2011), which support the promotion of physical activity via the education sector.
In the United States, schools have been involved in the public health and safety of children and adolescents since colonial times. Initially, schools helped combat infectious diseases; today they are being asked to lead the way in preventing and controlling the incidence of obesity, overweight, and diabetes (see chapters 5 and 6 for more). In the United States it has been estimated that over 54 million children and adolescents attend public and private elementary and secondary schools, where they spend approximately 6.5 hours per day for an average of 180 days per year. Additionally, over 1.1 million children attend pre-K schools, and over 11.5 million older adolescents attend community colleges or universities.
Because of the number of students they serve, schools at all levels are attractive public venues at which to disseminate positive physical activity messages and promote active lifestyles. Mandating increased physical activity in schools has also become popular recently, because policy makers believe that it can improve the adherence of students to varied curricular-based education to combat obesity, overweight, and diabetes, versus relying on students' voluntary compliance to lifestyle change.
National legislation in the United States, including the 2004 Child Nutrition and WIC Reauthorization Act (Lee et al. 2006),ties school funding to items such as school wellness policies that include promoting healthy eating and physical activity. National goals such as those contained in Healthy People 2010 and Healthy People 2020 (HP2020) also encourage curricular goals in school PE that include having students work at vigorous or moderate intensities for at least 50% of class time. Further, professional associations such as the National Association for Sport and Physical Education (NASPE; 2010) have recommended that elementary students engage in 150 minutes per week of school PE, and that secondary students acquire 225 PE minutes per week.
Although PE curricula have become the main focus for increasing physical activity in schools, youth cannot realistically meet physical activity guidelines (60 minutes per day; see the section on scientific evidence later in the chapter) by being active only in PE class. Even the very best physical education classes can offer only 20 to 30 minutes of physical activity time. Youth should be encouraged to acquire physical activity before, during, and after school in a variety of other ways, such as active transportation, play, sports, and leisure or recreation. It is also important to note that NASPE's weekly PE guidelines for children in schools address teaching structures and administrative issues as much as they do physical activity promotion.
Schools are a major source of potential influence on children and adolescents to adopt active lifestyles. Other sectors in society such as government agencies, families, and the media can also influence the adoption of behaviors that can help children and adolescents achieve caloric balance. Until recently, schools were built in neighborhoods, which often positively affected the whole community in relationship to physical activity, because they were within walking distance for most students and included places (e.g., open green spaces, outdoor tracks, indoor and outdoor basketball courts, gyms) at which youth and adults could be active. Schools have traditionally also offered opportunities for physical activity through PE classes, recess, and organized sports. However, with the new accountability requirements such as those of the No Child Left Behind legislation (2001), which encourage schools to focus on academic subjects such as mathematics and reading, physical education and recess time continue to be squeezed out.
Adding to these challenges, most new schools are being built on the outskirts of cities as a result of urban sprawl. This trend reduces opportunities for physical activity for members of the school community, because students must be bused to school or driven by family members. Research shows that whether schools are new or old, parents are concerned about safety, injury, and crime, which can cause them to limit physical activity opportunities for their children if they perceive the school environment to be unsafe.
Kinesiology and Physical Activity Outcomes for Youth
Selected chronic adaptations to physical activity and exercise are listed in the highlight box Adaptations to Physical Activity and Exercise Programming for Youth. The amount of physiological adaptation related to each of the identified benefits is dose dependent and influenced by the physical training principles discussed in chapter 2 and reviewed by Strong and colleagues (2005).
The exercise science-related benefits of physical activity for children, adolescents, and young adults are highly dependent on individual growth and development. Most youth experience very positive benefits associated with engaging in physical activity and exercise; however, maturation can influence the rate and timing of specific training adaptations.
Physiologically, participation in regular physical activity can help youth increase cardiorespiratory endurance ( .VO2max or .VO2peak) by 8 to 10%. Children and adolescents can increase their strength and muscular endurance; however, strength gains prior to puberty are mostly due to neural changes (i.e., better muscle recruitment) rather than hypertrophy (i.e., increased muscle size). There are published recommendations that pertain to youth strength and muscular endurance training (see Kenney, Wilmore, and Costill 2012 for more).
Youth can achieve significant and consistent improvements in bone health by participating in weight-bearing and muscular strength and endurance activities. The opportunity for increased bone mass in girls and boys occurs in puberty and premenarche. Their risks for metabolic dysfunction (e.g., related to HDL, triglyceride, and insulin levels; blood pressure; and percentage of body fat) and type 2 diabetes are also significantly reduced if they can get 60 minutes or more of physical activity daily.
Youth can experience many of the same biomechanical benefits reported for adults and older adults, particularly if they have the opportunity to develop a variety of motor skills by participating in a variety of physical activities. As children move through adolescence to young adulthood, they experience improved economy (i.e., lower energy cost) in activities such as running. Changes in economy have been attributed to changes in body size (i.e., filling out) and perhaps in stride frequency.
Youth engaged in organized sports have been reported to suffer more injuries that might limit future physical activity (particularly if they do not participate safely with protective equipment) than nonparticipants. However, except for information from descriptive studies of high school athletes, there is little evidence for this claim. Research on participation in school-based PE suggests that it is a very safe undertaking for the vast majority of students participating.
Behaviorally, the experiences that children (including pre-K and kindergarten students) have with physical activity, and the early behaviors that they develop as a result of participation, are thought to be critical to whether they become and remain active through adolescence and adulthood. Those who do not have the opportunities to develop the motor skills by participating in a variety of physical activities (as part of leisure time, recreation, PE, sports, and games) are most likely to become inactive, obese, or overweight adolescents, adults, and older adults.
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