Page:Popular Science Monthly Volume 41.djvu/325

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311
PHYSIOLOGY AND PREVENTION OF DISEASE.

and it has been calculated that this extra supply more than compensates for that expended in exercise—a circumstance which is readily understood when we consider that during muscular action more blood passes through the lungs, thus coming in contact with more oxygen. An increased supply of oxygen enhances the oxygenation of the food, thus directly facilitating the development of energy; and, besides, oxygen being a heart stimulant, the circulation will again be favorably affected.

Fourth. Assimilation becomes furthered by muscular exercise, for the reason that more blood passes through an organ during its activity, and consequently the latter becomes enabled to absorb more nourishment and lay by a larger quantity of reserve force.

Fifth. The blood, becoming more rapidly freed of its nutrient material by increased rapidity of assimilation, will be more ready to absorb such matters from the digestive organs. Improved absorption leads to more perfect digestion, and consequently muscular exercise aids considerably in the prevention of digestive disturbances. Further, when the digestion is enhanced, more food is called for. Increased appetite, together with improved digestion, absorption, oxidation, and assimilation, naturally exerts a marked influence upon the general nutrition of the system; therefore, exercise is a powerful means to the prevention of so many diseases caused by malnutrition.

Sixth. Muscular exercise by its direct effect upon the muscular system is the means not only of developing an active as well as a strong and healthy body, but likewise of storing up a large quantity of reserve force.

But, in order that muscular exercise may result in good physical development, it must be carried on systematically for a long period, and especially, for reasons already given, during the years of childhood. The nature of the exercise plays by no means an unimportant part in its efficacy. In order that all parts of the muscular system may be brought into play, gymnastics and calisthenics are indispensable. These exercises, however, should be supplemented by outdoor sports, such as games, rowing, swimming, skating, and the like, for two reasons: Firstly, the latter contain an element of pleasure without which that exhilaration which makes exercise doubly valuable is apt to be wanting; and, secondly, the air inhaled at the time is purer than that in closed rooms, an advantage which can not be overestimated.

But how can good physical development be placed within reach of all children? Only in one way, namely, by the introduction of effective methods of physical exercise into schools, for the reason that during the greater part of childhood systematic work outside of these institutions is, in the vast majority of cases, entirely out of the question.