Chapter IV.
Physical Exercise.
80. Importance of Bodily Exercise. Nothing is so essential to success in life as sound physical health. It enables us to work with energy and comfort, and better to endure unusual physical and mental strains. While others suffer the penalties of feebleness, a lower standard of functional activities, and premature decay, the fortunate possessor of a sound mind in a sound body is better prepared, with proper application, to endure the hardships and win the triumphs of life[13].
This element of physical capacity is as necessary to a useful and energetic life, as are mental endowment and intellectual acquirement. Instinct impels us to seek health and pleasure in muscular exercise. A healthy and vigorous child is never still except during sleep. The restless limbs and muscles of school children pent up for several hours, feel the need of movement, as a hungry man craves food. This natural desire for exercise, although too often overlooked, is really one of the necessities of life. One must be in ill health or of an imperfect nature, when he ceases to feel this impulse. Indeed, motion within proper bounds is essential to the full development and perfect maintenance of the bodily health. Unlike other machines, the human body becomes within reasonable limits, stronger and more capable the more it is used.
As our tenure of life at best is short, it is our duty to strive to live as free as possible from bodily ills. It is, therefore, of paramount importance to rightly exercise every part of the body, and this without undue effort or injurious strain.
Strictly speaking, physical exercise refers to the functional activity of each and every tissue, and properly includes the regulation of the functions and movements of the entire body. The word exercise, however, is used usually in a narrower sense as applied to those movements that are effected by the contraction of the voluntary muscles.
Brief reference will be made in this chapter only to such natural and systematic physical training as should enter into the life of every healthy person.
81. Muscular Activity. The body, as we have learned, is built up of certain elementary tissues which are combined to make bones, muscles, nerves, and other structures. The tissues, in turn, are made up of countless minute cells, each of which has its birth, lives its brief moment to do its work in the animal economy, is separated from the tissue of which it was a part, and is in due time eliminated by the organs of excretion,--the lungs, the skin, or the kidneys. Thus there is a continuous process of growth, of decay, and removal, among the individual cells of each tissue.
[Note. The Incessant Changes in Muscular Tissue. "In every tiny block of muscle there is a part which is really alive, there are parts which are becoming alive, there are parts which have been alive, and are now dying or dead; there is an upward rush from the lifeless to the living, a downward rush from the living to the dead. This is always going on, whether the muscle be quiet and at rest, or whether it be active and moving,--some of the capital of living material is being spent, changed into dead waste; some of the new food is always being raised into living capital. But when the muscle is called upon to do work, when it is put into movement, the expenditure is quickened, there is a run upon the living capital, the greater, the more urgent the call for action."--Professor Michael Foster.]
These ceaseless processes are greatly modified by the activity of the bodily functions. Every movement of a muscle, for instance, involves change in its component cells. And since the loss of every atom of the body is in direct relation to its activity, a second process is necessary to repair this constant waste; else the body would rapidly diminish in size and strength, and life itself would soon end. This process of repair is accomplished, as we shall learn in Chapters VI. and VII., by the organs of nutrition, which convert the food into blood.
Fig. 39.--Showing how the Muscles of the Back may be developed by a Moderate Amount of Dumb-Bell Exercise at Home. (From a photograph.)
82. Effect of Exercise upon the Muscles. Systematic exercise influences the growth and structure of the muscles of the body in a manner somewhat remarkable. Muscular exercise makes muscular tissue; from the lack of it, muscles become soft and wasted. Muscles properly exercised not only increase in size, both as a whole and in their individual structure, but are better enabled to get rid of material which tends to hamper their movements. Thus muscular exercise helps to remove any needless accumulation of fat, as well as useless waste matters, which may exist in the tissues. As fat forms no permanent structural part of the organism, its removal is, within limits, effected with no inconvenience.
Muscular strength provides the joints with more powerful ligaments and better developed bony parts. After long confinement to the bed from disease, the joints have wasted ligaments, thin cartilages, and the bones are of smaller proportions. Duly exercised muscles influence the size of the bones upon which they act. Thus the bones of a well-developed man are stronger, firmer, and larger than those of a feeble person.
He who has been physically well trained, has both a more complete and a more intelligent use of his muscles. He has acquired the art of causing his muscles to act in concert. Movements once difficult are now carried on with ease. The power of coördination is increased, so that a desired end is attained with the least amount of physical force and nervous energy. In learning to row, play baseball, ride the bicycle, or in any other exercises, the beginner makes his movements in a stiff and awkward manner. He will use and waste more muscular force in playing one game of ball, or in riding a mile on his wheel, than an expert would in doing ten times the work. He has not yet learned to balance one set of