For a long time, most people did not realize how important
physical fitness was. Today, however, we know that staying in
good physical condition not only makes life more enjoyable but
also quite possibly helps us live longer. That is why millions
of people today participate in some sort of strenuous exercise
several times each week.
There are four foundations to physical fitness. First, you
must eat in an intelligent way, based on principles of good
nutrition. Second, you must get plenty of rest and sleep. This
is vital when you are growing, and it is important at all times
of your life. Third, you must practice good hygiene and health
habits, and you should avoid dangerous substances such as tobacco
and narcotics. Fourth, you must get plenty of exercise. Exercise
keeps your muscles, heart, and lungs in good working order.
There are many different exercises, but just three basic kinds
are necessary for physical fitness. They are aerobic exercises,
stretchers, and strengtheners.
Aerobics
It used to be that doctors would recommend rest for their patients
with heart problems. This has changed. Now exercise is often
recommended to help strengthen weak hearts. Even normal, healthy
hearts benefit greatly from exercise. Doctors have discovered
that the heart is like any other muscle. Making it work strengthens
it. The heart is working hard when it is pumping hard.
Exercises that strengthen the heart and lungs are called aerobic
exercises. The word “aerobic” means “with oxygen.” Muscles need
oxygen in order to produce heat and energy. Our lungs collect
oxygen and feed it into our blood. Our hearts pump the blood
through the arteries and veins of our circulatory system, delivering
oxygen to every muscle in the body.
The blood also carries food to the muscles and takes away wastes
produced as the food and oxygen are used. When muscles have
too much waste, they do not work well. Your muscles become fatigued
(tired). They also become sore or develop cramps.
With an efficient heart and a strong pair of lungs, however,
you can work your muscles hard for a long time without getting
fatigued. And you can be sure that every organ and tissue in
your body is receiving a healthy supply of food and oxygen.
