Physiology and Hygiene for Secondary Schools

by Francis M. Walters

The use of these muscles is, in most instances, easily determined by observing the results of their contraction.

HYGIENE OF THE MUSCLES

The hygiene of the muscles is almost expressed by the one word exercise. It is a matter of everyday knowledge that the muscles are developed and strengthened by use, and that they become weak, soft, and flabby by disuse. The effects of exercise are, however, not limited to the large muscles attached to the skeleton, but are apparent also upon the involuntary muscles, whose work is so closely related to the vital processes. While it is true that exercise cannot be applied directly to the involuntary muscles, it is also true that exercise of the voluntary muscles causes[pg 257] a greater activity on the part of those that are involuntary and is indirectly a means of exercising them.

Exercise and Health.—In addition to its effects upon the muscles themselves, exercise is recognized as one of the most fundamental factors in the preservation of the health. Practically every process of the body is stimulated and the body as a whole invigorated by exercise properly taken. On the other hand, a lack of exercise has an effect upon the entire body somewhat similar to that observed upon a single muscle. It becomes weak, lacks energy, and in many instances actually loses weight when exercise is omitted. This shows exercise to supply an actual need and to be in harmony with the nature and plan of the body.

How Exercise benefits the Body.—In accounting for the healthful effects of exercise, it must be borne in mind that the body is essentially a motion-producing structure. Furthermore, its plan is such that the movements of its different parts aid indirectly the vital processes. The student will recall instances of such aid, as, for example, the assistance rendered by muscular contractions in the circulation of the blood and lymph, due to the valves in veins and lymph vessels, and the assistance rendered by abdominal movements in the propulsion of materials through the food canal. A fact not as yet brought out, however, is that exercise stimulates nutritive changes in the cells, thereby imparting to them new vigor and vitality. While this effect of exercise cannot be fully accounted for, two conditions that undoubtedly influence it are the following:

1. Exercise causes the blood to circulate more rapidly.

2. Exercise increases the movement of the lymph through the lymph vessels.

The increase in the flow of the blood and the lymph[pg 258] causes changes to take place more rapidly in the liquids around the cells, thereby increasing the supply of food and oxygen, and hastening the removal of waste.

One should plan for Exercise.—Since exercise is demanded by the nature and plan of the body, to neglect it is a serious matter. People do not purposely omit exercise, but from lack of time or from its interference with the daily routine of duties, the needed amount is frequently not taken. Especially is this true of students and others who follow sedentary occupations. People of this class should plan for exercise as they plan for the other great needs of the body—food, sleep, clothing, etc. It is only by making a sufficient amount of muscular work or play a regular part of the daily program that the needs of the body for exercise are adequately supplied.

Amount and Kind of Exercise.—The amount of exercise required varies greatly with different individuals, and definite recommendations cannot be made. For each individual also the amount should vary with the physical condition and the other demands made upon the energy. One in health should exercise sufficiently to keep the muscles firm to the touch and the body in a vigorous condition.