Muscularity

“ The striated muscles, as a [pg 260] rule, are attached to the mechanical devices found in the skeleton, and bring about the voluntary, movements. The non-striated muscles surround the parts on which they act, and produce involuntary movements. Both, however, are under the control of the nervous system. To bring about the opposing movements of the body, the striated muscles are arranged in pairs; and to increase their motion, the bones are used as levers. Physical exercise is necessary both for the development of the muscles and for the health and vigor of the entire body. ”

“ Both evidently derive the principle of the activity that marks them from the same external and internal media; but, while the muscle, a mechanical organ, is limited to the obedient transformation of the force assigned to it, under the form of heat, into a measurable amount of work, the nerve, a vital organ, remains impenetrable and inaccessible to our calculations, and exerts its characteristic and sovereign powers in its own way, through a series of operations that escape all estimates of their force and heat. On the part of the muscular system, every thing can be measured ”

“ Still, there are a number of muscles which are used almost exclusively, so that other muscles, with their connecting tendons, bones, and nerves, fail, from sheer neglect, to contribute to the health of the whole body. How many women exercise fully the large muscles of the back and loins, or the muscles of the abdomen? Women who wash, or those who work in field or garden. Yet these important muscles, when used, contribute much not only to the health of the body in general, but also to the vigor of the organs lying underneath them. ”

“ He cannot put forth the full strength of his body without first making a deep inspiration; and by making a deep inspiration, and maintaining afterwards the chest in an expanded state, which is essential to the continuance of his muscular effort, he so alters the mechanical relations of the two sides of his body that the muscles of his right side act with a superior efficacy; and, to render the inequality still greater, the muscles of the left side act with a mechanical disadvantage. ”

“ A contracted muscle, according to this view, is like a strong band of india-rubber pulling on two pieces of wood and drawing them together. In like manner, when a muscle contracts, a similar elastic power is developed that pulls upon the bones and causes movement. When the contraction ceases, the muscle returns to its original length, again by elasticity, but acting in the opposite way.
What is this property of irritability by virtue of which the muscle responds to a stimulus and contracts? ”

“ Making the Muscles Strong.—No persons use all of the five hundred muscles in the body every day. In slow walking only about twenty muscles are used, while in running more than four times that number are called into action. Muscles which are not used get lazy and weak.
Every time a muscle is made to act the blood vessels enlarge and bring to it more blood to supply food. The more food the muscle has the stronger it grows. The right arm is used more than the left in most persons. ”

“ It necessitates careful diet and constant exercise for a long period, and proves equally beneficial to both sexes. This book has been written in vain if the reader has not grasped by now that the activity of the muscles implies the activity of all the organs in the body. Accordingly, the whole muscular system is by appropriate methods given frequent exercise: gentle at first; never exhausting; but constantly increasing as the strength grows. The result is a general development of the organs throughout the body, which will in time work a complete metamorphosis in the individual’s physique. ”

“ A stronger muscle must have a stronger bone to resist its contractions; must have stronger correlated muscles and ligaments to secure the neighbouring articulations; must have larger blood-vessels to bring it supplies; must have a more massive nerve to transmit stimulus, and some extra development of a nervous centre to supply the extra stimulus. The question arises, then,—do variations of the appropriate kinds occur simultaneously in all these co-operative parts? Have we any reason to think that the parts spontaneously increase or decrease together? ”

“ This diagram will give you a conception of what we mean by a muscle. It shows the muscles of a frog's leg. You observe that, as a rule, a muscle springs from a bone, and is attached at the other end to another bone, a joint, sometimes two or more joints, intervening. One end of such a muscle as the gastrocnemius (Fig. 6) muscle terminates in what is called a tendon or sinew—a fibrous structure which is attached to a membrane covering the bone. The muscles are the living ropes that pull the parts of the animal machine. ”

“ From these facts, as well as from the great force with which the muscle contracts, one must conclude that the muscle is a transformer of energy—that within its protoplasm, chemical changes take place whereby the potential energy of oxygen and food is converted into the kinetic energy of motion.
Fig. 113—Capillaries of muscles. Plan of Using Muscular Force.—Two difficulties have to be overcome in the using of muscular force in the body. The first of these is due to the fact that the muscles exert their force only when they contract. They can pull but not push. ”

“ The muscles are like the various bits of machinery which go to make up a steam engine. In performing their work they produce heat and motion. The fuel which supplies this force is taken into the body as food, prepared for use in the intestinal tract, and from there carried by the blood to be stored up in the muscles and various tissues as latent force. Through the circulation of the blood the whole body is heated by muscular exercise. It stands to reason that continual exercise of a certain kind will develop certain muscles. ”

“ But don’t think for a moment that physiology lends itself to the cult of muscle. Here is a youth whose biceps are his better part: like most of us, he gets what he aims at—some local renown as an athlete. But what does he pay for the whistle? His violent ‘sports’ do not materially increase the measure of blood which sustains him: if the muscles get more than their share, their gain implies loss elsewhere, to the brain, commonly, and, indeed, to all the vital organs. ”

“ Structure of Voluntary Muscles. The main substance which clothes the bony framework of the body, and which forms about two-fifths of its weight, is the voluntary muscular tissue. These muscles do not cover and surround the bones in continuous sheets, but consist of separate bundles of flesh, varying in size and length, many of which are capable of independent movement.
Each muscle has its own set of blood-vessels, lymphatics, and nerves. It is the blood that gives the red color to the flesh. ”

“ How the Muscles do their Work.—A tiny nerve [Pg 143] thread runs from the spinal cord or brain to every muscle thread. Messages sent through the nerve threads to the muscles make them act. A muscle can act in only two ways (Fig. 84) . It can become shorter or longer. When it gets shorter, we say it contracts. When it stretches out, it is said to relax.
A muscle cannot contract more than one fourth of its length. To pull the forearm up, the brain sends a message to the muscle fixed by one end at the shoulder and by the other end to a bone at the elbow. ”

“ It is difficult for the youth to hold his back straight and his shoulders back; he is awkward and ungainly in his movements and becomes easily fatigued because of the condition of his muscles. [31] But the muscles follow immediately in their development and rapidly gain volume and tonicity, filling out the arms, legs, back and shoulders with large masses of firm muscular tissue. The growth of these muscle masses changes the dimensions of the youth and he fills out in his girths as rapidly as, in the previous period, he increased in length measurements. ”

“ Every muscle, in fact, consists in the first place of a mass of muscular substance. This muscular substance is made up of an immense number of soft strings or fibres, all running in one direction and done up into large and small bundles. At either end of the muscle these soft muscular fibres are joined on to firmer but thinner fibres of connective or fibrous{29} tissue. And these thinner but firmer fibres make up the cord or band of tendon with which the muscle finishes off at either end. ”

“ Of course this possibility of variation is of great advantage in our use of our muscles. It depends upon the very large number of individual fibers of which even our smallest muscles are made up. Whenever any single fiber contracts, it pulls to its full extent; if only a few become active, the pull of the whole muscle will be slight; as more come into action, more force will be exerted; the muscle will show its utmost power when all the fibers are contracting at once. We are conscious of greater mental effort when we make a powerful muscular contraction. ”

“ Fig. 112—Muscle cells from the heart, highly magnified (after Schäfer) . The Muscular Stimulus.—The inactive, or resting, condition of a muscle is that of relaxation. It does work through contracting. It becomes active, or contracts, only when it is being acted upon by some force outside of itself, and it relaxes again when this force is withdrawn. Any kind of force which, by acting on muscles, causes them to contract, is called a muscular stimulus. Electricity, chemicals of different kinds, and mechanical force may be so applied to the muscles as to cause them to contract. ”

“ Most of the muscles act upon the bones, so as to produce the effects of a lever of the third kind, as it is termed by mechanics, where the power acts between the centre of motion and the weight; hence it has a mechanical disadvantage; as an instance of this, the muscle which bends the forearm, is inserted about one eighth or one tenth of the distance from the centre of motion that the hand is, where the weight or resistance is applied; hence the muscle must exert a force eight or ten times greater than the weight to be raised. ”

“ Indeed, all that I want to bring about muscular contraction is, not a metamorphosis of muscle which issues in the development of muscular force, nor a transformation of heat into muscular force, but simply a supply of electricity during the state of muscular inaction which will counteract the tendency which the muscle always has to contract as an elastic body. ”

“ So far as the mere muscular movement goes, the sensation is that of being well oiled. As for instance, in a natural walk, where the swinging muscles and the standing muscles act and rest in alternate rhythmic action, the chest is held high, the side muscles free to move in, harmony with the legs, and all the spring in the body brought into play through inclining slightly forward and pushing with the ball of the back foot, the arms swinging naturally without tension. ”

“ This perfect equilibrium involves in turn a condition of the muscles in which they are transformed from a dead weight to a living force. In this condition there is said to be a complete connection of all the muscles with the center of gravity; independent motions and independent reactions are eliminated, and a combined force is instantly brought to bear upon whatever work is required. The spine is perfectly straight, the waist muscles firm, and the weight, in the standing posture, is supported upon the balls of the feet. ”

“ The prodigies of force that astonish us are due to a very simple cause, and can be accounted for under the common law that, of two muscles having the same mass and the same energy, the shorter one is capable of raising the more considerable weight. We may figure muscular fiber as a spiral spring, habitually relaxed, which, under nervous action, flies back upon itself. ”

“ During all these stages the structure of the muscle—or to prevent all equivoque, let us say the substance of the muscle—has been changing, not indeed in any degree appreciable to the eye, but appreciable by the more decisive tests of chemical and physiological reactions. Yet inasmuch as in the ordinary course of things the waste is quickly repaired, the muscle in repose once more regains its original state, once more represents 10 units of contractility. Now let us consider what takes place when extra labor is thrown upon the muscle, when exercise causes growth. ”

“ Here, again, do we find the richness of feeling associated without exception in races with a fine development of the neuro-muscular and vaso-motor systems. This is related to muscular exercise. When we come to the regal faculty, the will, our modern psychology again tells us that will must express itself in terms of muscular activity, and that power of the will in its origin bears a relation to firmness of muscle, to power of muscular contraction. ”

“ Further, inasmuch as muscular movement is one of the chief ends, or the most important means to the chief ends of animal life, we find the animal body abounding in motor mechanisms, in which the prime mover is muscular contraction, while the machinery is supplied by complicated arrangements of muscles with such indifferent tissues as bone, cartilage, and tendon. ”

“ Some muscles assist one another in their action, while others have different actions; according to their shapes, the course of their fibres, and the structure of the parts they move.
According to the shape and nature of the bones to be moved, and of the motions to be performed, the muscles are either long, or short; slender, or bulky; straight, or round. Where a great motion is required, as in the leg, or arm, the muscles are long; where a small motion is necessary, they are short; for a strong motion they are thick, and for a weak one slender. ”