Cooley's Cyclopædia of Practical Receipts and Collateral Information in the Arts, Manufactures, Professions, and Trades..., Sixth Edition, Volume I

Part 157

Chapter 1573,510 wordsPublic domain

If the quantities in the above table be converted into ounces it will be found that nearly 8-3/4 oz. more oxygen were absorbed and 13 oz. more of carbonic anhydride eliminated by the lungs during a work-day than during a rest-day.[290] It must be stated that during the work-day an interval of rest was taken, and that the labour was by no means excessive.

[Footnote 290: Parkes.]

Hirn and Speck appear to have conclusively proved that the formation of the carbonic anhydride occurs in the muscles, and that it is rapidly carried off from them. In short, this latter result seems essential for the development of muscular energy. At any rate it is found that if the respiratory movements be in any way interfered with during exercise, and the elimination of carbonic anhydride in any degree checked, the muscular power rapidly diminishes.

An examination of Pettenkofer and Voit's table shows that exercise gives rise to the escape of a large amount of water from the body, and to a slightly diminished quantity of urea.

Since the accumulation of the superfluous carbon supplied by the food gives rise to morbid and diseased states of the body,[291] we shall now be enabled to understand why deficient exercise should be a source of physical ill-being, and why, on the contrary, the proper use of the muscles should be so essential a condition for the maintenance of health, since it is in them that the great formation of the eliminated carbon is effected. We shall also not fail to see why, since during exercise the excretion of water is so largely increased, the blood necessarily becomes less diluted and richer in quantity.

[Footnote 291: "Deficient exercise is one of the causes which produce those nutritional alterations in the lung which we class as tuberculosis."--PARKES.]

Whilst insufficiency of exercise gives rise to a weak action of the heart, and very frequently to fatty degeneration of that organ, exercise that is not excessive, although it increases the beats of the heart from ten to thirty beyond this acceleration, and imparting greater force to the pulsations, does not interfere with their regularity. Furthermore, muscular exercise, by considerably augmenting the flow of the blood through the whole body, the heart included, exercises a most beneficial function, "since it causes in all organs a more rapid outflow of plasma and absorption--in other words, a quicker renewal. In this way also it removes the products of their action, which accumulate in organs, and restores the power of action to various parts of the body."[292]

[Footnote 292: Parkes.]

Palpitation, enlargement, and valvular disease of the heart result from excessive or injudicious exercise. Wherever, therefore, fatigue or embarrassment of the heart shows itself rest must be had recourse to. Persons having weak hearts suffer greatly in ascending mountain or other heights.

The effect of exercise upon the kidneys is to diminish the quantity of water, as well as the chloride of sodium and other chlorides in the urine. As we have seen, the urea is very slightly lower; but after much exertion the uric acid is increased. There is also a slight increase in the amounts of sulphates and carbonic anhydride. Parkes could find no alteration in the phosphates. The diminution of water and the chlorides is due to the excretion of these by the skin, the function of which is greatly augmented by exercise. No urea escapes by the skin, but many acids (probably fatty ones) are liberated by that organ. Speck has shown that during exercise the amount of fluid is nearly double what it is when the body is quiescent.

This escape of fluid by perspiration doubtless affords an explanation of a diminution in the quantity of the excreta from the bowels. The fæces exhibit no decrease in nitrogen.

Exercise increases the growth of the muscles, making them at the same time harder, and also causing them to obey more readily the behests of the will. Prolonged or excessive exertion, without sufficient rest, has been found to interfere with their nutrition, and to cause them to become soft.

There is a tolerably general impression that much exercise tends to cripple the development of the mental faculties, and this idea is said to have received support from the circumstance that the athletes at our universities seldom signalise themselves in contests of learning. But this fact, it has been suggested, may be explained by the athletic exercise being indulged in to such an extent as to leave no time for cultivating the mind. If an illustration were required to prove that great bodily energy is quite consonant with mental vigour it might be found in the life of the late Professor Wilson, of Edinburgh. On this point Dr Parkes says: "Considering that perfect nutrition is not possible except with bodily activity, we should infer that sufficient exercise would be necessary for the perfect performance of mental work."

As regards the changes that take place in the muscles during exercise Dr Parkes writes: "The chief changes that take place in the muscles during action appear to be these: there is a considerable increase of temperature (Helmholtz), which, up to a certain point, is proportioned to the amount of work; it is also proportioned to the kind, being less when the muscle is allowed to shorten than if prevented from shortening (Heidenhain); the neutral or alkaline reaction of the tranquil muscle becomes acid from para-lactic acid and acid potassium phosphate; the venous blood passing from the muscles becomes much darker in colour, is much less rich in oxygen, and contains much more carbonic acid (Sczelkow); the extractive matters soluble in water lessen, those soluble in alcohol increase (Helmholtz, in frogs); the amount of water increases (in tetanus, J. Ranke), and the blood is consequently poorer in water; the amount of albumen in tetanus is less, according to Ranke, but Kühne has pointed out that the numbers do not justify the inference."

Liebig stated that the creatin is increased (but this was an inference from old observations on the extractum carnis of hunted animals, and requires confirmation). Sarokin has stated the same fact in respect to the frog. The electro-motor currents show a decided diminution during contraction.

That great molecular changes go on in the contracting muscles is certain, but their exact nature is not clear; according to Ludimar Hermann there is a jelly-like separation and coagulation of the myosin, and then a resumption of its prior form, so that there is a continual splitting of the muscular structure into a myosin coagulum, carbonic acid, and a free acid, and this constitutes the main molecular movement. But no direct evidence has been given of this.

The increased heat, the great amount of carbonic acid, and the disappearance of oxygen, combined with the respiratory phenomena already noted, all seem to show that an active oxidation goes on; and it is very probable that this is the source of the muscular action. The oxidation may be conceived to take place in two ways--either during rest oxygen is absorbed and stored up in the muscles, and gradually acts there, producing a substance which, when the muscle contracts, splits up into lactic acid, carbonic acid, &c.; or, on the other hand, during the contraction an increased absorption of oxygen goes on in the blood, and acts on the muscles, or on the substances in the blood circulating through the muscles. The first view is strengthened by some of Pettenkofer and Voit's experiments, which show that during rest a certain amount of storage of oxygen goes on, which no doubt in part occurs in the muscles themselves.

Indeed, it has been inferred that it is this stored-up oxygen, and not that breathed in at the time, which is used in muscular action. The increased oxidation gives us a reason why the nitrogenous food must be increased during periods of great exertion.

An increase in the supply of oxygen is a necessity for increased muscular action; but Pettenkofer and Voit's observations have shown that the absorption of oxygen is dependent on the amount and action of the nitrogenous structures of the body, so that, as a matter of course, if more oxygen is required for increased muscular work, more nitrogenous food is necessary. But, apart from this, although experiments on the amount of nitrogenous elimination show no very great change on the whole, there is no doubt that, with constant regular exercise, a muscle enlarges, becomes thicker, heavier, contains more solid matter, and, in fact, has gained in nitrogen. This process may be slow, but it is certain; and the nitrogen must either be supplied by increased food, or be taken from other parts.

So that, although we do not know the exact changes going on in the muscles, it is regarded as certain that regular exercise produces in them an addition of nitrogenous tissue.

Whether this addition occurs, as usually believed, in the period of rest succeeding action, when in some unexplained way the destruction which it is presumed has taken place is not only repaired, but is exceeded (a process difficult to understand), or whether the addition of nitrogen is actually made during the action of the muscle, must be left undecided for the present.

The substances which are thus oxidised in the muscle or in the blood circulating through it, and from which the energy manifested as heat or muscular movement is believed to be derived, may probably be of different kinds. Under ordinary circumstances the experiments of Fick and Wislicenus and others, and the arguments of Traube, seem sufficient to show that the non-nitrogenous substances, and perhaps especially the fats, furnish the chief substances acted upon. But it is probable that the nitrogenous substances also furnish a contingent of force. The exact mode in which the energy thus liberated by oxidation is made to assume the form of mechanical motion is quite obscure.

There seems little doubt that the exhaustion of muscles is chiefly owing to two causes--first and principally to the accumulation in them of the products of their own action (especially para-lactic acid); and secondly, from the exhaustion of the supply of oxygen. Hence rest is necessary, in order that the blood may neutralise and carry away the products of action, so that the muscle may recover its neutrality and its normal electrical currents, and may again acquire oxygen in sufficient quantity for the next contraction.

In the case of all muscles these intervals of action and of exhaustion take place, in part even of the period which is called exercise; but the rest is not sufficient entirely to restore it. In the case of the heart the rest between the contractions (about two thirds of the time) is sufficient to allow the muscle to perfectly recover itself.

The foregoing remarks on the effects of muscular exercise will have prepared us for the inference which statistics abundantly support, viz. that, other conditions being favorable, the healthiest occupation is that which consists in the practice (of course within reasonable limits) of manual labour in the open air.

The Rev. Professor Haughton, in his work entitled 'A New Theory of Manual Labour,' has drawn up a table (which we append) of the amount of force expended during various kinds of work. It represents the number of tons lifted one foot per diem:--

Professor Haughton has devised a formula by means of which a certain amount of walking exercise may be made to represent its equivalent in manual labour. He points out that walking on a level surface is equivalent to raising one twentieth part of the weight of the body through the distance walked.

When ascending any height, the whole weight of the body is, of course, raised through the ascent. The formula is--

(W + W_{l}) × D --------------- 20 × 2240

where W is the weight of the person; W_{l} the weight carried (if any); D the distance walked in feet; 20 the co-efficient of traction; and 2240 the number of pounds in a ton. The result is the number of tons raised one foot. To get the distance in feet 5280 must be multiplied by the number of miles walked.

Supposing a man to weigh 150 lbs. with his clothes, by the employment of the above formula we should arrive at the following results:--

+----------------------+------------+ | |Work done in| | Kind of Exercise. |tons lifted | | | 1 foot. | +----------------------+------------+ | Walking 1 mile | 17·67 | +----------------------+------------+ | Walking 2 miles | 35·34 | +----------------------+------------+ | Walking 10 miles | 176·7 | +----------------------+------------+ | Walking 20 miles | 353·4 | +----------------------+------------+ | Walking 1 mile | | | and carrying 60 lbs.| 24·75 | +----------------------+------------+ | Walking 2 miles | | | and carrying 60 lbs.| 49·5 | +----------------------+------------+ | Walking 10 miles | | | and carrying 60 lbs.| 247·5 | +----------------------+------------+ | Walking 20 miles | | | and carrying 60 lbs.| 495 | +----------------------+------------+

From the above data something like a rough approximation may be formed of the daily amount of exercise requisite for a healthy male adult.

Since 500 tons lifted a foot is extremely hard work, the number of miles corresponding to this extreme amount of labour would, if persevered in, be objectionable.

Dr Parkes, regarding 300 tons lifted a foot as an average day's work for a healthy man, thinks that walking exercise equivalent to half that amount should be taken daily. This, or a 150 tons, represents a nine miles' walk. He, however, qualifies the suggestion by adding "that, as there is much exertion taken in the ordinary business of life, this amount may be in many cases reduced;" and concludes by saying, "It is not possible to lay down rules to meet all cases, but probably every man with the above facts before him could fix the amount necessary for himself with tolerable accuracy."

For muscular exercise to be safe and efficient, it must be taken under certain conditions and precautions. We have noticed the evil effects of immoderate bodily exertion on the heart. The lungs are no less seriously affected by an excessive indulgence in it, which shows itself in spitting of blood and in congestion of the pulmonary vessels. Congestion of the lungs brought on by overtaxed bodily strength very frequently causes the death of horses in the hunting field.

These facts, therefore, not only point to the importance of avoiding undue or extreme exertion,[293] but also to the necessity of ensuring the full and uncramped play of the respiratory organs during exercise, and the consequent removal of any impediment in the way of tight clothing that in any manner interferes with their freedom of exercise. Laboured respiration and sighing are indications of pulmonary congestion, and counsel temporary rest and abstention from exercise.

[Footnote 293: "There must be proper intervals of rest, or the store of oxygen, and of the material in the muscles which is to be metamorphosed during contraction, cannot take place."

--PARKES.]

The great augmentation in the excretion of carbon which leaves the lungs in the form of carbonic anhydride during exercise has been already referred to. As this carbon is derived from the food, it follows that in the intervals of exercise an increase of carbonaceous diet is necessary. For this purpose physiologists prefer the fatty to the amylaceous varieties of diet. It has been already stated why at the same time the nitrogenous food must be increased during periods of great exertion. There seems little doubt that water is the best drink that can be taken during moderate as well as great exercise.... It is best taken in small quantities and frequently. Spirits are decidedly prejudicial, and indispose to bodily exertion. They are hurtful because they lessen the exhalation of carbonic anhydride from the lungs. Trainers never allow them, and but very little wine or beer.

The thirst that not unfrequently accompanies exercise is due to the great escape of water from the skin which has been already alluded to. This liberation of moisture, being also accompanied, as already explained, by a large excretion of the chlorides and, perhaps, by other salts. Dr Parkes advises the use of an additional supply of chloride of sodium to the diet of those taking much exercise; he suggests that probably potassium chloride and phosphate might be added with advantage.

The evaporation from the skin has the effect of reducing the bodily temperature and rendering it equable. This temperature, however, falls very rapidly after exertion is over; and hence at this time it is always advisable to guard against the chance of a chill by covering the body over. Flannel forms the best protection. Keeping the skin clean by daily ablution greatly aids in the escape of fluid during exercise.

The large amount of carbonic anhydride given off by the lungs during bodily exercise explains the advantages of open air exercise, and why walking in the fresh air produces such excellent effects in some forms of dyspepsia. This increased exhalation of carbonic anhydride also points to the importance of thorough ventilation when indoor exercise is taken, particularly by large bodies of men or women, as in riding schools and on the treadmill. The mortality amongst miners, whose labour is performed in confined and ill-ventilated spaces is very great. According to Mr Simon, with the exception of those who work in the well-ventilated mines of Durham and Northumberland, the 300,000 miners in England break down prematurely from bronchitis and pneumonia, caused by the atmosphere in which they are compelled to work.

=EXPAN'SION.= All substances, solid, liquid, and gaseous, when chemical change does not take place, expand by heat, and contract by cold. In some of them this property occurs in a greater degree than in others, but is constant for the same substance under the same circumstances. The chemist avails himself of this property in the construction of his thermometer; the wheelwright, in fixing on the tire of his wheels; the engineer, in restoring to the perpendicular the leaning walls of buildings, &c.

This expansion by heat is of great importance in the manufactures, as allowance has to be made of it in every purpose where metals are employed.

The following is a list of the expansion of the chief metals, &c., when heated from 32° to 212° Fahr., or from 0° to 100° Cent.:--

_Substance._ _Expansion._ In bulk. In length. Glass 1 in 384 1 in 1150 Platinum 1 in 377 1 in 1311 Steel 1 in 309 1 in 926 Iron 1 in 282 1 in 846 Gold 1 in 227 1 in 682 Copper 1 in 194 1 in 582 Brass 1 in 179 1 in 536 Silver 1 in 175 1 in 524 Tin 1 in 172 1 in 516 Lead 1 in 117 1 in 351 Zinc 1 in 113 1 in 340

Of the liquids, they expand as follows, when heated from 0° to 100° Cent., or from 32° to 212° Fahr.:--

Mercury 1 in 55 in bulk. Water 1 in 21 in bulk.

Gases practically all expand alike; that is to say, for every degree Fahrenheit a gas expands 1/491 of its bulk at 32°, and for every degree Centigrade 1/273 of their volume at 0°C.

An example will show the importance of this. Suppose an iron bar, connecting two sides of a building, and of a length of about 85 feet. The increase in length by heat of this bar would make it 1 inch longer in summer than in winter; and it would, if no allowance be made, pull or thrust the walls to this extent each year.

=EXPEC'TORANTS.= _Syn._ EXPECTORANTIA, L. Medicines that promote the secretion of the trachial and bronchial mucus. According to Dr Good, true expectorants are "those medicines which rather promote the separation of the viscid phlegm with which the bronchiæ are loaded, than simply inviscate and dilute it; though these are also treated as expectorants by many writers." Ammoniacum, antimonials, assaf[oe]tida, the balsams of Peru and tolu, benzoic acid, benzoin; the fumes of vinegar, tar, and several of the volatile oils; garlic, ipecacuanha, the oleo-resins, squills, tartarised antimony, and the smoke of tobacco and stramonium, are among the principal substances commonly called expectorants. Tartarised antimony, squills, chlorine, and ammoniacal gases, have also been used (diluted) to provoke the coughing and favour the expulsion of foreign bodies from the air-passages; and also to favour the expectoration of mucus, pus, and membranous concretions, when the local irritation is not sufficiently great. (Schwilgue.) Expectorants are commonly employed in pulmonary complaints and affections of the air tubes, attended by a vitiated state of the mucus, or an imperfect performance of the natural functions of the secretory vessels. "Of all classes of the materia medica, none are more uncertain in their action than expectorants." (Pereira.) The act of ejecting matter from the chest is called EXPECTORATION.