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Part Five Other Aspects of Wellness
lift. You move your body by contracting
your muscles. Having strong muscles
will allow you to move your body more
effi ciently. Developing strength can also
help you avoid some sports injuries.
Obviously, weight training is an excellent
activity for developing strength and lean
muscle mass, 15-7.
Flexibility
Flexibility is the ability to move
your joints through a full range of
motion. Joints are the places in your
body where two bones meet. Elbows,
knees, shoulders, hips, and ankles are
all examples of joints. A high degree
of fl exibility helps prevent injury to
muscles that control movement of the
joints.
Females generally have the poten-
tial for greater fl exibility than males.
Stretching exercises can help increase
fl exibility.
Body Composition
Body composition is the percentage
of different types of tissues in the body.
High body fat percentage is a risk factor
for a number of diseases. Therefore,
body composition is a component of
total physical fi tness.
If you are at or below a healthy
weight, you may ask, “Do I really
need to exercise?” The answer is “yes.”
Everyone at all ages needs to be physi-
cally active. As described earlier,
physical activity has many benefi ts
besides helping people maintain a
healthy weight. It is an essential compo-
nent in maintaining overall good health
and fi tness.
Remember, weight is not a
reliable indicator of body composition.
Someone who has a large percentage
of lean body tissue may be overweight
according to his or her body mass index
(BMI). However, he or she is not overfat.
Exercise helps the body burn fat
and build muscle. Glucose is the body’s
chief source of energy. After about 20
minutes of aerobic activity, however,
the body begins to use fat for energy.
Doing activities that increase muscular
endurance and strength helps build
muscle tissue. Increasing the proportion
of muscle mass in the body raises the
basal metabolic rate (BMR), thus helping
Extend
Your Knowledge
Building a Better Body
Interview a number of body builders. Learn what
motivates their interest in body building. Is their focus
to increase muscle strength, endurance, or both?
Compare their answers to recognized benefits for
increasing muscle strength. Are the body builders’
reasons different from benefits identified in this
chapter?
15-7 Using muscles to lift weights helps
develop strength.