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Educating the Student Body
Flexibility:
A health-related component of physical fit-
ness that relates to the range of motion avail-
able at a joint.
Frequency:
The number of times an exercise or activity 
is performed, usually expressed in episodes 
per week (e.g., two times per week).
Health:
A state of complete physical, mental, and 
social well-being and not merely the absence 
of disease or infirmity.
Health promotion: 
The process of enabling people to increase 
control over and improve their health. To 
reach a state of complete physical, mental, 
and social well-being, an individual or group 
must be able to identify and realize aspira-
tions, satisfy needs, and change or cope 
with the environment. Health is a resource 
for everyday life, not the objective of living, 
and is a positive concept emphasizing social 
and personal resources, as well as physical 
capacities. 
Health-related fitness:
The components of physical fitness referred 
to as health-related components are cardio-
respiratory fitness, muscular strength and 
endurance, body composition, flexibility, 
and balance.
Healthy weight: 
In children and youth, a level of body fat 
at which comorbidities are not observed; 
in adults a BMI of between 18.5 and 
24.9 kg/m
2
. 
Incidence: 
The frequency of new cases of a condition 
or disease within a defined time period. 
Incidence is commonly measured in terms of 
new cases per 1,000 (or 100,000) popula-
tion at risk per year. 

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Copyright © National Academy of Sciences. All rights reserved.
Educating the Student Body: Taking Physical Activity and Physical Education to School
Appendix A
 
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Inhibitory control
Refers to the ability to override a strong
(inhibition): 
internal or external pull to appropriately 
act within the demands imposed by the 
environment.
Intensity:
A characteristic of a physical activity that 
represents how much work is being per-
formed in a given period of time (i.e., the 
rate of energy expenditure; absolute inten-
sity) or the magnitude of effort required to 
perform an activity as perceived by a person 
(relative intensity). See also Light-intensity 
physical activity, Moderate-intensity physi-
cal activity, Sedentary physical activity, and 
Vigorous-intensity physical activity, .
Intervention: 
A policy, program, or action intended to 
bring about identifiable outcomes.
Intramural sports:
Organized and supervised sports programs of 
within-school teams and clubs that provide 
opportunities for all students to participate.
Light-intensity physical
Physical activity with a rate of energy expen-
activity:
diture of >1.5 to <3.0 METs (>1.5 to 
<3 times the energy required for sitting at 
rest), such as strolling, making a bed, or 
cooking.
Metabolic equivalent of
One MET is the rate of energy expenditure
task: 
while sitting at rest. It represents approxi-
mately 3.5 milliliters of oxygen consumption 
per kilogram of body weight per minute. 
Moderate-intensity
Physical exertion that is equivalent to brisk
physical activity:
walking. Such activities are usually done at 
between 3.5 and 6.0 times resting metabolic 
rate.
Musculoskeletal fitness: 
Fitness that includes muscular strength, 
muscular endurance, muscular power, and 
muscular flexibility.

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Copyright © National Academy of Sciences. All rights reserved.
Educating the Student Body: Taking Physical Activity and Physical Education to School
390