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TRENDS IN PHYSICAL ACTIVITY bEHAVIORS AMONG YOUTH
This section reviews trends in physical activity behaviors among youth, 
examining in turn vigorous- or moderate-intensity activity, sedentary and 
light-intensity activity, and physical activity not necessarily related to 
school.
Vigorous- or Moderate-Intensity Physical Activity 
Although estimates of children and adolescents currently achieving the 
recommended volume of vigorous- or moderate-intensity physical activity 
vary depending on how the data were collected, it is clear that few children 
are sufficiently physically active. An important question is whether the cur-
rent status of physical activity among youth is an improvement, a worsen-
ing, or no different relative to previous years. If the situation is improving 
(i.e., children have been becoming more active), no changes or new efforts 
may be warranted; if the situation is stable or worsening, actions are 
needed. Few data sources provide clear and convincing evidence on trends 
in children’s level of physical activity, but taken together the evidence is 
persuasive that children and adolescents in the United States have become 
increasingly less physically active over the past 40-50 years. 
The YRBS provides self-reported information on physical activ-
ity among high school students for 1993-2011. Although the data span 
20 years, trends in vigorous- or moderate-intensity physical activity are 
obscured because the survey questions have been modified over time to 
align with changes in the recommended volume of physical activity for 
youth (annual surveillance reports from CDC’s website for 1995, 1997, 
1999, 2001, 2003, 2005, 2007, 2009, and 2011) (see Figure 2-10 and 
Box 2-5). The largest change is an increase from 70 percent in 1995 to 84 
percent in 2005 in the percentage of students who participate in physical 
education and who report averaging more than 20 minutes per class exer-
cising or playing sports. In 2011 there was a sharp increase over 2009 in 
the proportion of students reporting at least 60 minutes of vigorous- or 
moderate-intensity physical activity on at least 5 days in the preceding 
week (37 percent to 50 percent) and a corresponding decline in the number 
reporting that much activity on no days of the preceding week (23 percent 
to 14 percent) (see Figure 2-10). These sharp changes are thought to be an 
artifact arising from a shift in the format of the questionnaire such that 
students had fewer opportunities to describe the types and amounts of their 
physical activity.
A clear example of a decline in physical activity among youth is the 
decrease in the proportion of schoolchildren walking or bicycling to school. 
Between 1969 and 2001, this proportion dropped from 42 percent to 

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Educating the Student Body: Taking Physical Activity and Physical Education to School
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