The present section deals with the use of muscular activity for its hygienic effect upon the body as a whole; the next section with its employment for special purposes. Exercises undertaken for their general good effect are frequently spoken of as "hygienic"; the term is, however, objectionable, and we shall speak of them as general muscular exercises.
General muscular exercise is of hygienic value because it produces the physiological results which have been enumerated in the preceding section, -results which have been shown to constitute essential elements of the normal internal environment of the cells of the body. To review the separate offices of this ministry to the normal conditions of the body:
- General exercises should produce to a considerable extent those physical and chemical changes which accompany muscular contraction, with the resulting effects upon the physiological condition of the muscle itself and upon the general internal environment, the blood and lymph.
- They should exercise, and so train, the heat-regulating mechanism.
- They should tend to relieve vascular congestion in internal organs, bringing the blood in larger quantities to the skin.
- They should afford training to the heart.
- They should increase the ventilation of the lungs.
- They should increase the flow of lymph in the lymphatics, and thereby improve the environmental conditions of all the cells in the body.
- They should exert a favorable influence upon the digestive processes, promoting proper secretion and absorption, and tending to prevent unhealthful conditions leading to constipation.
Such being the physiological ends sought for, we may conclude, as to the character of such exercises:
1. They should consist of rhythmic rather than sustained contractions. These involve less fatigue, are more enjoyable, and especially facilitate the flow of blood and lymph.
2. They should be vigorous, somewhat prolonged, and should usually be continuous. A brisk walk or a run meets most demands; so do bicycling and many games. The strolls or saunters which are too frequently mistaken for exercise do not meet the reasonable hygienic demands of the body; they involve only an insignificant increase of chemical activity in the muscles, they hardly affect respiration, they do not train the heart; in short, they do not produce adequate physiological effects to accomplish hygienic ends.
3. They should involve considerable movement on the part of the trunk as well as the limbs. Many excellent forms of exercise, such as bicycling, are somewhat deficient in this respect. It is not meant that sudden and violent trunk movements are called for, but that hygienic exercise should bring full change and relief from the constrained positions of the trunk imposed by the sedentary occupations of modern life. A vigorous walk, with its accompanying increase of breathing and trunk movements, fencing, and games which involve the throwing and catching of a ball are especially good in this respect.
4. They should be accompanied by full and free respiration. The importance of this requirement needs no comment. Constrictive clothing should not be allowed to interfere, and, as far as possible, the trunk should be held erect, the neck and shoulders back, so as to permit the freest movement of the upper ribs.
5. It is advisable not to confine oneself wholly to one form of exercise. Similar considerations to those which hold in the choice of food apply to some extent to exercise. At the same time it must be admitted that perfect health can frequently be maintained to old age by using only one kind of general exercise, such, for example, as walking.
The relation of general exercise to fatigue is a matter of considerable interest and also of importance in correlating muscular work with the other work of life. Fatigue of the whole organism is a very complicated matter and involves much more than the total amount of chemical change in the muscles and of the resulting waste products in the system as a whole. We, may, for example, be made very tired by unpleasant sensations from the joints and tendons, or by walking in shoes which do not permit free play to the bones, ligaments, tendons, and muscles of the foot; and this, even when the amount of muscular exertion involved may have been slight. It is well known that merely standing still for a time will frequently cause more fatigue than will a longer time spent in walking.
Again, some forms of exercise throw a relatively large share of the total work on some muscle or small group of muscles, while others distribute the total work more evenly over larger groups. Walking and running are very unlike in this respect; in the former the weight of the body must be lifted from the ground with each step,-especially when we walk very erect,-by the extensor muscles of the leg, and chiefly by the extensors of the ankle joint; running, on the other hand, consists in a continual falling forward and the restoration of equilibrium by a more general action of the muscles of the body as a whole. A walk of four and a half miles an hour is much more fatiguing to a person in good training than a run of four and a half miles an hour, because in the former case a few muscles are thrown into very vigorous contraction and so give rise to severe local sensations of fatigue, sometimes accompanied by cramps in the muscles.
Bicycle riding is remarkable for distributing the total work over large numbers of strong muscles, so that the amount done by each is relatively small; consequently, where there is but little hill-climbing or no strong head winds, local fatigue is but slight, although the total work done by the body is considerable. Actual measurements of the carbon dioxide excreted have shown that this is much greater per minute in a ride of eight miles an hour on a smooth level track, than in walking three and a half miles an hour; in other words, the total work is greater. The well-known increase of perspiration brought about by such moderate riding points in the same direction; the chemical changes in the body are greater and so is the associated heat production; and yet any cyclist knows that the conscious fatigue of the ride is as nothing compared with that of the walk. Moreover, in wheeling the weight of the body is not supported on the feet, and we are thus to a large extent relieved from the unpleasant sensations produced by pressure and jar in the ankle and knee joints. It is a characteristic of moderate or even fairly vigorous bicycle riding that it produces a maximum of chemical change with a minimum of fatigue. This is of great practical importance. The larger production of carbon dioxide involves deeper breathing, and, as the student now well knows, increased work on the part of the heart.
Within proper limits this is, of course, good for the heart; there is some danger, however, that in the absence of conscious fatigue we may throw upon that organ more work than is good for it, and medical experience leaves no doubt that many cases of injury to the heart have resulted from injudicious cycling; that is to say, from "scorching" against strong head winds and in "showing grit" by refusing to get off and walk up very steep hills. There are occasions when it is not wise to be too ambitious, and when "discretion is the better part of valor."
Somewhat similar considerations apply to most of our more active games, such as basketball, football, tether ball, hockey, polo, etc. They are perfectly safe for healthy people when not played more vigorously than the training of the heart justifies; the fact that there is an element of danger in them is no reason why they should not be used, but it is a very good reason why they should not be worked to extremes, and especially why we should be sure, from competent medical advice, that there is in those who play them no organic trouble to begin with, and that players are in good training when they play most intensely.
The choice of the kind of muscular work and exercise involves so many considerations other than those which are strictly physiological and hygienic that it is impossible to give in an elementary treatise like this any detailed discussion of the special merits and defects of each. We often have other aims in view besides the purely hygienic; thus the group games, such as football, baseball, basketball, hockey, etc., train the spirit of cooperation and may be made useful means of moral training. In camping in the woods, canoeing is not simply a means of exercise, but also a means of transportation; and under other conditions the same thing is true of horseback riding, rowing, etc. Wood chopping, digging, porterage, and plowing are valuable means of livelihood. It is believed, however, that the principles here given will help the individual to form a correct judgment as to whether his work in life supplies him incidentally or inevitably with the needed general muscular activity for hygienic purposes, and, if it does not, to plan to meet the want intelligently.
The combination of muscular exercise with some other pursuit is highly desirable, and when practicable often simplifies the hygienic conduct of life. But it is nothing short of a hygienic misfortune to lose the youthful love of activity for its own sake. It is well as we grow older to have golf, or a horse to be exercised (!), or a fishing preserve in the woods, to "take us out in the open air" and make us use our muscles. But a human being who is dependent upon something of this kind to drag him into activity cuts a sorry figure from a moral standpoint. Man's highest distinction is the fact that his actions may arise so largely from processes of psychic life within rather than from some immediate stimulus from without. The proper hygienic conduct of life involves moral fiber as well as physical fiber, and this is especially true of that absolutely essential part of hygienic conduct which depends upon the use of organs like the skeletal muscles, which are so largely subordinate to the commands of the will.
In their enthusiasm for athletic games and outdoor sports in youth, and for other outdoor activities in middle life, the American people are always in danger of losing their love for the various forms of walking, such as tramping and mountain climbing. Walking is the one form of general exercise for sound people which can always be had for the taking. For this reason, if for no other, it should ever be a part of all sound physical training to conserve the love of tramping and the ability to walk. Apart from the obvious fact that it is in this way that we can get close to nature and the real beauty of the world in which we live, the possession of the love of the activity involved is one of the most precious possessions of our hygienic life. The man or woman who does not keep and improve this power by use must look forward to the same fate as the servant in the parable who hid his talent in a napkin, only to have it taken from him in the end.
A word of warning is needed against the folly of supposing that fresh air is a substitute for muscular activity. Fresh air is one of our greatest hygienic blessings, and it is very desirable to live an outdoor life as far as possible. But too many think that lounging in the shade, or riding in the open air in an automobile, a carriage, or an electric car, does for them what muscular exercise alone can do. Especially as age creeps over us and the love of activity wanes from its disuse, more and more does the idea grow upon us that "fresh air" is everything. To many the possession of a comfortable carriage and a pair of thoroughbreds is a misfortune. At one of our most beautiful summer resorts someone said to a local physician, "Medical practice at such a place as this must be very unremunerative." "By no means," replied the man of experience; "people come here where they are tempted to overeat; in the place of exercise they lie back on the cushions of their carriages while they are driven about; their adipose tissue increases rapidly, and very soon it is true that to no class of people is the doctor so absolutely essential as to them." The student can easily make the application for himself. Indigestion, fatty degeneration, insomnia, loss of appetite, nervous prostration, and kindred ills rarely come to those who labor with their hands; and these ills can be largely prevented, even in those who must engage in sedentary occupations, by a wise and intelligent conduct of the physical life, and especially by the daily employment of an hour or so of vigorous general muscular activity properly correlated with the other work of life.
Hough T & Sedgwick WT (1906). Muscular Activity (Chapter XVII), The Human Mechanism Its Physiology and Hygiene and The Sanitation Of Its Surroundings, Ginn & Company, pg 314-320.