Читать книгу A Practical Physiology: A Text-Book for Higher Schools - Albert F. Blaisdell - Страница 19

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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 muscles against their antagonists.

Fig. 40.--The Standard Special Chest Weight.

A convenient machine by means of which all the muscles of the body may be easily and pleasantly exercised with sufficient variations in the movements to relieve it of monotony.

A space 6 ft wide, 6 ft deep, and 7 ft high nearly in front of the machine is required for exercise.]

In time, however, acts which were first done only with effort and by a conscious will, become automatic. The will ceases to concern itself. By what is called reflex action, memory is developed in the spinal cord and the muscular centers (sec. 273). There is thus a great saving of actual brain work, and one important cause of fatigue is removed.

83. Effect of Exercise on Important Organs. The importance of regular exercise is best understood by noting its effects upon the principal organs of the body. As the action of the heart is increased both in force and frequency during exercise, the flow of blood throughout the body is augmented. This results from the force of the muscular contractions which play their part in pressing the blood in the veins onward towards the heart. Exercise also induces a more vigorous respiration, and under increased breathing efforts the lung capacity is increased and the size of the chest is enlarged. The amount of air inspired and expired in a given time is much larger than if the body were at rest. The blood is thus supplied with a much larger amount of oxygen from the air inhaled, and gives off to the air a corresponding excess of carbon dioxid and water.

Again, exercise stimulates and strengthens the organs of digestion. The appetite is improved, as is especially noted after exercise in the open air. The digestion is more complete, absorption becomes more rapid, the peristaltic movements of the bowels are promoted, and the circulation through the liver is more vigorous. More food is taken to supply the force necessary for the maintenance of the mechanical movements. Ample exercise also checks the tendency towards a torpid circulation in the larger digestive organs, as the stomach and the liver, so common with those who eat heartily, but lead sedentary lives. In short, exercise may be regarded as a great regulator of nutrition.

Exercise increases the flow of blood through the small vessels of the skin, and thus increases the radiation of heat from the surface. If the exercise be vigorous and the weather hot, a profuse sweat ensues, the rapid evaporation of which cools the body. The skin is thus a most important regulator of the bodily temperature, and prevents any rise above the normal which would otherwise result from vigorous exercise. (See secs. 226 and 241).

84. Effect of Exercise upon the Personal Appearance. Judicious and systematic exercise, if moderately employed, soon gives a more upright and symmetrical figure, and an easier and more graceful carriage. Rounded shoulders become square, the awkward gait disappears, and there is seen a graceful poise to the head and a bearing of the body which mark those whose muscles have been well trained. A perfectly formed skeleton and well-developed muscles give the graceful contour and perfect outline to the human body. The lean, soft limbs of those who have never had any physical education, often look as if they belonged to persons recovering from sickness. The effects of sound physical exercise are well exhibited in the aspect of the neck, shoulders, and chest of one who has been well trained. This is noticeable in gymnasts and others who practice upon the horizontal bar, with chest weights, dumb-bells, and other apparatus which develop more especially the muscles of the upper half of the trunk.

Fig. 41.--Young Woman practicing at Home with the "Whitely Exerciser." (From a photograph)

Exercise improves the condition of the tissues generally. They become more elastic, and in all respects sounder. The skin becomes firm, clear, and wholesome. Hence, every part of the surface of the body rapidly takes on a change in contour, and soon assumes that appearance of vigor and soundness which marks those of firm physical condition. The delicate, ruddy aspect of the complexion, the swing about the body and the bearing of the head and shoulders, of young women whose physical training has been efficient, are in marked contrast with those characteristics in persons whose education in this respect has been neglected.

85. Effect of Unsuitable or Excessive Exercise. But exercise, like everything else which contributes to our welfare, may be carried to excess. The words excessive and unsuitable, when applied to muscular exertion, are relative terms, and apply to the individual rather than to amount of work done. Thus what may be excessive for one person, might be suitable and beneficial to another. Then the condition of the individual, rather than the character of the muscular work, is always a most important factor.

Breathlessness is, perhaps, the most common effect of undue exertion. Let a middle-aged person, who is out of practice, run a certain distance, and he is soon troubled with his breathing. The respirations become irregular, and there is a sense of oppression in his chest. He pants, and his strength gives out. His chest, and not his legs, has failed him. He is said to be "out of breath." He might have practiced dumb-bells or rowed for some time without inconvenience.

The heart is often overstrained, and at times has been ruptured during violent exertion, as in lifting an immense weight. The various forms of heart-disease are common with those whose occupations involve severe muscular effort, as professional athletes and oarsmen. Hæmorrhages of various kinds, especially from the lungs, or rupture of blood-vessels in the brain, are not uncommon results of over-exertion.

Excessive repetition of muscular movements may lead to permanent contractions of the parts involved. Thus sailors, mechanics, and others frequently develop a rigidity of the tendons of the hand which prevents the full extension of the fingers. So stenographers, telegraphers and writers occasionally suffer from permanent contractions of certain muscles of the arm, known as writer's cramp, due to their excessive use. But the accidents which now and then may result from severe physical exertion, should discourage no one from securing the benefits which accrue from moderate and reasonable exercise.

86. Muscular Fatigue. We all know how tiresome it is to hold the arm outstretched horizontally even for a few moments. A single muscle, the deltoid, in this case does most of the work. Even in a vigorous man, this muscle can act no longer than four to six minutes before the arm drops helpless. We may prolong the period by a strong effort of the will, but a time soon comes when by no possible effort are we able to hold out the arm. The muscle is said to be fatigued. It has by no means lost its contractile power, for if we apply a strong electric stimulus to it, the fatigue seems to disappear. Thus we see the functional power of a muscle has a definite limit, and in fatigue that limit is reached.

Fig. 42.--A Well-Equipped Gymnasium. (From a photograph.)

The strength of the muscle, its physical condition, the work it has done, and the mental condition of the individual, all modify the state of fatigue. In those difficult acts which involve a special effort of the will, the matter of nerve exhaustion is largely concerned. Thus, the incessant movements in St. Vitus' dance result in comparatively little fatigue, because there is no association of the brain with the muscular action. If a strong man should attempt to perform voluntarily the same movements, he would soon have to rest. None of the movements which are performed independently of the will, as the heart-beats and breathing movements, ever involve the sensation of fatigue. As a result of fatigue the normal irritability of muscular tissue becomes weakened, and its force of contraction is lessened. There is, also, often noticed in fatigue a peculiar tremor of the muscles, rendering their movements uncertain. The stiffness of the muscles which comes on during severe exercise, or the day after, are familiar results of fatigue.

This sense of fatigue should put us on guard against danger. It is a kind of regulator which serves in the ordinary actions of life to warn us not to exceed the limits of useful exercise. Fatigue summons us to rest long before all the force of the motor organs has been expended, just as the sensation of hunger warns us that we need food, long before the body has become weak from the lack of nourishment.

We should never forget that it is highly essential to maintain an unused reserve of power, just as a cautious merchant always keeps at the bank an unexpended balance of money. If he overspends his money he is bankrupt, and the person who overspends his strength is for the time physically bankrupt. In each case the process of recovery is slow and painful.

87. Rest for the Muscles. Rest is necessary for the tissues, that they may repair the losses sustained by work; that is, a period of rest must alternate with a period of activity. Even the heart, beating ceaselessly, has its periods of absolute rest to alternate with those of work. A steam-engine is always slowly, but surely, losing its fitness for work. At last it stops from the need of repair. Unlike the engine, the body is constantly renewing itself and undergoing continual repair. Were it not for this power to repair and renew its various tissues, the body would soon be worn out.

This repair is really a renovation of the structure. Rest and work are relative terms, directly opposed to each other. Work quickens the pulse and the respiration, while rest slows both. During sleep the voluntary muscles are relaxed, and those of organic life work with less energy. The pulse and the respiration are less frequent, and the temperature lower than when awake. Hence sleep, "tired Nature's sweet restorer," may be regarded as a complete rest.

The periods of rest should vary with the kind of exercise. Thus exercise which produces breathlessness requires frequent but short rests. The trained runner, finding his respiration embarrassed, stops a moment to regain his breath. Exercises of endurance cause fatigue less quickly than those of speed, but require longer rest. Thus a man not used to long distances may walk a number of hours without stopping, but while fatigue is slow to result, it is also slow to disappear. Hence a lengthy period of rest is necessary before he is able to renew his journey.

88. Amount of Physical Exercise Required. The amount of physical exercise that can be safely performed by each person, is a most important and practical question. No rule can be laid down, for what one person bears well, may prove very injurious to another. To a certain extent, each must be guided by his own judgment. If, after taking exercise, we feel fatigued and irritable, are subject to headache and sleeplessness, or find it difficult to apply the mind to its work, it is plain that we have been taxing our strength unduly, and the warnings should be heeded.

Age is an important factor in the problem, as a young man may do with ease and safety, what might be injurious to an older person. In youth, when the body is making its most active development, the judicious use of games, sports, and gymnastics is most beneficial. In advanced life, both the power and the inclination for exercise fail, but even then effort should be made to take a certain reasonable amount of exercise.

Abundant evidence shows that physical development is most active from thirteen to seventeen years of age; this manifests itself clearly by increase in weight. Hence this period of life is of great consequence. If at this age a boy or girl is subjected to undue physical strain, the development may suffer, the growth be retarded, and the foundation laid for future ill health.

Fig. 43.--Student exercising in the School Gymnasium on the Rowing Machine. (From a photograph.)

The proper amount of exercise must vary greatly with circumstances. It may be laid down as a fairly safe rule, that a person of average height and weight, engaged in study or in any indoor or sedentary occupation, should take an amount of exercise equivalent to walking five or six miles a day. Growing children, as a rule, take more exercise than this, while most men working indoors take far less, and many women take less exercise than men. Exercise may be varied in many ways, the more the better; but for the most part it should always be taken in the open air.

89. Time for Exercise. It is not prudent to do hard work or take severe exercise, just before or just after a full meal. The best time is one or two hours after a meal. Vigorous exercise while the stomach is busily digesting food, may prove injurious, and is apt to result sooner or later in dyspepsia. On the other hand, severe exercise should not be taken on an empty stomach. Those who do much work or study before breakfast, should first take a light lunch, just enough to prevent any faint feeling. With this precaution, there is no better time for moderate exercise than the early morning.

In the case of children, physical exercises should not be undertaken when they are overtired or hungry. Neither is it judicious for adults to take vigorous exercise in the evening, after a long and arduous day's work.

90. Walking, Running, and Jumping. Walking is generally regarded as the simplest and most convenient mode of taking exercise. Man is essentially a walking animal. When taken with a special object in view, it is the best and most pleasant of all physical activities. It is suited for individuals of all ages and occupations, and for residents of every climate. The child, the athlete, and the aged are all able to indulge in this simple and effective means of keeping the body in health.

In walking, the muscles of the entire body are brought into action, and the movements of breathing and the circulation of the blood are increased. The body should be erect, the chest thrown out, the head and shoulders held back, and the stride long and elastic. It is an excellent custom to add to the usefulness of this fine exercise, by deep, voluntary inhalations of pure air.

Running is an excellent exercise for children and young people, but should be sparingly indulged in after the age of thirty-five. If it be accompanied with a feeling of faintness, breathlessness, and palpitation of the heart, the exercise is too severe, and its continuance may do serious harm. Running as an exercise is beneficial to those who have kept themselves in practice and in sound condition. It brings into play nearly every muscle of the body, and thus serves to develop the power of endurance, as well as strength and capacity for rapid movement.

Jumping may well be left to boys and young men under twenty, but skipping with a rope, allied to jumping, is an admirable and beneficial form of exercise. It brings into action many muscles without putting undue strain upon any particular group.

91. Skating, Swimming, and Rowing. Skating is a delightful and invigorating exercise. It calls into play a great variety of muscles, and is admirably adapted for almost all ages. It strengthens the ankles and helps give an easy and graceful carriage to the body. Skating is especially valuable, as it can be enjoyed when other out-door exercises are not convenient.

Every child above ten years of age should be taught to swim. The art, once mastered, is never forgotten. It calls into use a wide combination of muscles. This accomplishment, so easily learned, should be a part of our education, as well as baseball or bicycling, as it may chance to any one to save his own life or that of a companion.

In many respects rowing is one of the most perfect exercises at our command. It expands the chest, strengthens the body, and gives tone to the muscles of the abdomen. It is very suitable for girls and women, as no other exercise is so well adapted to remedy the muscular defects so marked in their sex. Even elderly persons can row day after day without difficulty. The degree of muscular effort required, can be regulated so that those with weak hearts and weak lungs can adjust themselves to the exercise.

92. Bicycling as an Exercise. The bicycle as a means of taking exercise has come into popular use with remarkable rapidity. Sharp competition bids fair to make the wheel more popular and less expensive than ever. Its phenomenal use by persons of all ages and in all stations of life, is proof of the enthusiasm with which this athletic exercise is employed by women as well as by men.

Mechanical skill has removed most of the risks to health and person which once existed. A good machine, used by its owner with judgment, is the most convenient, the safest, and the least expensive means of traveling for pleasure or exercise. It is doing more than any other form of exercise to improve the bodily condition of thousands whose occupations confine them all day to sedentary work. Dependent upon no one but himself, the cyclist has his means of exercise always at hand. No preparation is necessary to take a spin of ten miles or so on the road, during a summer evening or before breakfast.

Bicycling brings into active use the muscles of the legs as well as those of the trunk and arms. It seems to benefit those who suffer from dyspepsia, constipation, and functional disorders of the liver.

A special caution must be used against overdoing in cycling, for the temptation by rivalry, making a record, by social competition on the road, is stronger in this form of exercise than in any other, especially for young folks. Many cases have occurred of permanent injury, and even loss of life, from collapse simply by excessive exertion and exhaustion.

93. Outdoor Games and Physical Education. While outdoor games are not necessary to maintain health, yet we can scarcely overestimate the part that the great games of baseball, football, tennis, golf, and croquet, play in the physical development of young people. When played in moderation and under suitable conditions, they are most useful and beneficial exercises. They are played in the open air, and demand a great variety of vigorous muscular movement, with a considerable amount of skill and adroitness of action. These games not only involve healthful exercise, but develop all those manly and wholesome qualities so essential to success in life.

A vigorous body is well-nigh essential to success, but equally important are readiness of action, sound judgment, good temper, personal courage, a sense of fair play, and above all, a spirit of honor. Outdoor games, when played in a reasonable and honorable manner, are most efficient and practical means to develop these qualities in young people.

94. The School and Physical Education. The advantages to be derived, during the school period, from the proper care and development of the body, should be understood and appreciated by school officials, teachers, and parents. The school period is the best time to shape the lives of pupils, not mentally or morally alone, but physically as well. This is the time, by the use of a few daily exercises at school, to draw back the rounding shoulders, to form the habit of sitting and standing erect, to build up strong and comely arms and chests, and otherwise to train pupils to those methods which will serve to ripen them into vigorous and well-knit men and women.

Teachers can by a little effort gain the knowledge requisite properly to instruct their pupils in a few systematic exercises. Gratifying results will follow just as the teacher and pupils evince interest and judgment in the work. It is found by experience that pupils are not only quick to learn, but look forward eagerly to the physical exercises as an interesting change from the routine of school life.

There should be a stated time for these school exercises, as for any other duty. There can be practiced in the schoolroom a great variety of interesting and useful exercises, which call for little or no expense for apparatus. Such exercises should no more interfere with the children's usual games than any other study does. Under no circumstances should the play hours be curtailed.

95. Physical Exercises in School. Physical exercises of some sort, then, should be provided for pupils in our schools, especially in large towns and cities, where there is little opportunity for outdoor games, and they should form a part of the regular course of study. The object should be the promotion of sound health rather than the development of muscle, or performing feats of agility or strength. Exercises with dumb-bells and wands, or even without any apparatus, practiced a few times a day, for five minutes at a time, do a great deal of good. They relax the tension of body and mind, and introduce an element of pleasure into the routine of school life. They increase the breathing power and quicken the action of the heart.

Fig. 44.--Physical Exercises as carried on in Schools. (From photographs.)

[Note. "In early boyhood and youth nothing can replace the active sports so much enjoyed at this period; and while no needless restrictions should be placed upon them, consideration should be paid to the amount, and especially to the character, of the games pursued by delicate youth. For these it would be better to develop the weakened parts by means of systematic physical exercises and by lighter sports."--Dr. John M. Keating on "Physical Development" in Pepper's Cyclopædia of the Diseases of Children.]

If vigorously and systematically carried out, these exercises invigorate all the tissues and organs of the body, and stimulate them to renewed activity. They serve to offset the lack of proper ventilation, faulty positions at the desks, and the prolonged inaction of the muscles. To secure the greatest benefit from physical training in school, it is important that the pupils be interested in these exercises, and consider them a recreation, and not a task[14].

96. Practical Points about Physical Exercise. The main object in undertaking systematic and graduated physical exercises is not to learn to do mere feats of strength and skill, but the better to fit the individual for the duties and the work of life. Exercises should be considered with reference to their availability from the learner's standpoint. The most beneficial exercises ordinarily are the gentle ones, in which no strain is put upon the heart and the respiration. The special aim is to secure the equal use of all the muscles, not the development of a few. The performance of feats of strength should never come within the scope of any educational scheme. Exercises which call for sustained effort, violent exertion, or sudden strain are best avoided by those who have had no preparation or training.

Regular exercise, not sudden and occasional prolonged exertion, is necessary for health. The man or woman who works in an office or store all the week, and on Sunday or a holiday indulges in a long spin on the bicycle, often receives more harm than good from the exertion. Exercise should be taken, so far as is convenient, in the open air, or in a large and well-ventilated room.[15]

After the more violent exercises, as baseball, football, a long ride on the bicycle, or even after a prolonged walk, a warm bath should be taken at the first convenient opportunity. Care should be taken to rub down thoroughly, and to change a part or all of the clothing. Exercise is comparatively valueless until the idea of taking it for health is quite forgotten in the interest and pleasure excited by the occasion. No exercise should be carried to such a degree as to cause fatigue or exhaustion. Keep warmly clad after exercise, avoid chills, and always stop exercising as soon as fatigue is felt.

Wear clothing which allows free play to all the muscles of the body. The clothing should be light, loose, and made of wool. Care should be taken not to take cold by standing about in clothes which are damp with perspiration. In brisk walking and climbing hills keep the mouth shut, especially in cold weather, and breathe through the nose, regulating the pace so that it can be done without discomfort.

97. Effect of Alcoholic Liquors and Tobacco upon Physical Culture. As a result of the unusual attention given to physical culture in the last few years, hundreds of special instructors are now employed in training young people in the theory and practice of physical exercise. These expert teachers, to do their work with thoroughness and discipline, recognize the necessity of looking after the daily living of their students. The time of rising and retiring, the hours of sleep, the dress, the care of the diet, and many other details of personal health become an important part of the training.

Recognizing the fact that alcoholic drink and tobacco are so disastrous to efficiency in any system of physical training, these instructors rigidly forbid the use of these drugs under all circumstances. While this principle is perhaps more rigorously enforced in training for athletic contests, it applies equally to those who have in view only the maintenance of health.

Books on Physical Education. There are many excellent books on physical education, which are easily obtained for reading or for reference. Among these one of the most useful and suggestive is Blackie's well-known book, "How to Get Strong and how to Stay so." This little book is full of kindly advice and practical suggestions to those who may wish to begin to practice health exercises at home with inexpensive apparatus. For more advanced work, Lagrange's "Physiology of Bodily Exercise" and the Introduction to Maclaren's "Physical Education" may be consulted. A notable article on "Physical Training" by Joseph H. Sears, an Ex-Captain of the Harvard Football Team, may be found in Roosevelt's "In Sickness and in Health."

Price lists and catalogues of all kinds of gymnastic apparatus are easily obtained on application to firms handling such goods.

Various Systems of Physical Exercises. The recent revival of popular interest in physical education has done much to call the attention of the public to the usefulness and importance of a more thorough and systematic use of physical exercises, both at home and in the schools. It is not within the scope of this book to describe the various systems of gymnastic and calisthenic exercises now in common use in this country. For the most part they have been modified and rearranged from other sources, notably from the two great systems, i.e., Swedish and German.

For a most comprehensive work on the Swedish system, the teacher is referred to the "Swedish System of Educational Gymnastics," with 264 illustrations, by Baron Nils Posse. There is also a small manual for teachers, called "Handbook of School Gymnastics of the Swedish Systems," by the same author.