Strong and capacious lungs are needed in order that we may acquire the regular and almost unconscious habit of taking in great quantities of air at the moment of inspiration. And such lungs result from deep breathing, in proportion to the purity of the air inhaled.
A grown-up male of average bodily development has usually in his lungs about two hundred cubic inches of air. An ordinary inspiration, such as is made by people unversed in taking care of their bodies accounts for about thirty cubic inches of air. But inflate the lungs as much as you possibly can, and you draw in some one hundred and thirty cubic inches of air, or one hundred inches more than you do with a “quiet” breath. Now, when you inhale but thirty cubic inches of air and exhale it quietly, only that same quantity leaves your lungs. But a strong exinspiration of air will force out about one hundred cubic inches more than you breathed in.
It will be seen then that a forced expiration, by expelling more air than would leave the lungs by a “quiet” expiration, will relieve the lungs of some hundred cubic-inches of more or less impure air that would otherwise-linger in them to your harm. And as the ordinary quantity of air that belongs in the lungs must be made up at the next inspiration, pure air takes the place of the impure that has been gotten. rid of by the- forced expiration, and the blood throughout the body is much benefited thereby.
Now, bear in mind at all times, when considering the act and the benefits of breathing, that the lungs, once air is driven from them, will refill themselves automatically. Thus, if you can increase the capacity of your lungs,: you must take in more air there-after when you breathe; you cannot help taking more air into larger lungs, for the increased amount of – room is there and-Nature will see to it that more air is taken in.
Strengthening the lungs and increasing their capacity for air are accomplished by one and the same means the studied practice of deep breathing in the – open air. Fill your lungs as deeply as you can, and you cause the ribs to rise and to bulge forward. The intercostal muscles facilitate this expansion of the chest, one rib being pulled upward and driven forward by the same movement of the rib above it. The, diaphragm does its share by rising and forcing the lungs to expand outward. The ribs are obliged to accommodate themselves to the movement. The intercostal muscles become stronger (through this constant exercise) and the costal cartilages are forced to stretch in order to accommodate this new demand on their expansion. In time, by repeated exercise, the cartilages permit of great increase in size of the cavity in which the lungs rest. And the lungs, both on account of the work of their own muscles and of that of the greater amount of chest space in which they lie, become larger and more enduring.
Thus, through deep breathing conducted as an exercise, the lungs become larger, have more space in which to move and expand, and have furthermore a. greater air capacity. Such capacity, once it is created, must be filled. With better developed lungs you must breathe more air, and with more air passing through the delicate membranes of the organs the blood must become purer. The heart is benefited, as was described in the preceding chapter, and indeed the effect for good extends to the remotest tissues of the body.
There is no more interesting experiment for one who is training his body to do its full duty than to make full, deep and proper breathing an important. part of the work; and take measurements of the chest from time to time. It is surprising how quickly results for the better are noted. And he who is attaining a proper chest development has started on the road to abounding health.
When walking, always do so with the shoulders well back and the chin confidently up. Never walk with such a poise of the body that the chest can be at all compressed. Cultivate the expansion of the chest at all times, and you will be richly repaid for the effort.