A good exercise program for muscle activity

When you are at rest all the muscles of the body use only about one thirtieth of the oxygen they can use during maximum effort. With a well-rounded exercise program, they can be made to use much more. When they do, the heart will respond, pumping harder to get more oxygen-carrying blood into circulation, and over a period of time, heart pumping efficiency will increase; the heart will pump more blood with each stroke. At the same time, lung capacity-much of it never used in sedentary living-will enlarge to absorb and feed more oxygen into the blood- stream. The higher oxygen content will aid muscle as circulation improves in both quality and body; the capillaries penetrating into muscles will open and become more effective.

A good exercise program also will help to strengthen the muscles around the veins in the lower part of the body, and this is of considerable importance. When you stand, the veins in the legs expand and there may be a tendency for them to become distended with blood which pools in them 50 that less blood is available for circulation through the rest of the body. As less blood returns to the heart from the veins in the lower part of the body, the heart, with less blood to eject with each beat, tries to compensate by increasing its beat rate. But this is not always effective and does impose added stress on the heart. The amount of blood that can pool in the lower veins depends considerably on the amount of pressure by the muscle tissues around the veins. If the tissues are tight and firm, the expansion of the veins is limited.

Soft muscles without tone do not provide much external support to the veins to prevent their expansion. Thus, a good program of exercise can have many admirable effects throughout the body-in terms of health of heart, lungs, muscles, blood vessels. We suggest that you read, in connection with this discussion, the contents of Chapter 8 on exercise.

A word here about nutrition; It, too, is vital in the proper care of muscles. A good diet containing the sources of protein described in Chapter 6 will help you build and maintain strong, healthy muscles.