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Sedentary or Light-Intensity Physical Activity
Recent evidence indicates that light-intensity physical activity, although 
not likely a substitute for vigorous- or moderate-intensity physical activ-
ity, is beneficial to health. Research has focused on the detrimental health 
impact of sedentary-intensity physical activity, usually sitting or watching 
television, but the evidence can just as well be described as showing benefits 
from light-intensity physical activity (see Box 2-4). The relative merits of 
different levels and combinations of physical activity intensities are being 
investigated and discussed, but the lower end of the spectrum of rate of 
energy expenditure is now receiving attention previously reserved for the 
higher end.
An important aspect of sedentary-intensity physical activity is the 
large portion of waking hours it fills. Assuming about 15 hours per day 
of wakefulness, sedentary and light-intensity physical activities fill 80 per-
cent of waking hours for youth who spend 3 hours doing vigorous- or 
moderate-intensity physical activities (see Figure 2-6). For youth just meet-
ing the 60-minute daily recommendation for the latter activities, the former 
would fill 93 percent of the day. For the majority of youth not meeting the 

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Educating the Student Body: Taking Physical Activity and Physical Education to School
Status and Trends of Physical Activity Behaviors and Related School Policies
 
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