EX′ERCISE

is e ential to the healthy performance of the functions of both body and mind. Without it, the stomach acts feebly, the bowels become inactive, and the circulation of the blood languid and imperfect; the chest contracts, the respiration becomes impeded, the brain is insufficiently supplied with pure arterial blood, the mind grows lethargic, the complexion a umes a sickly and effeminate hue, and the features generally lack the energy and expre ion which they po e in perfect health. With exercise, the bodily functions are performed with vigour and regularity, the constitution is thereby strengthened, and the attacks of disease repelled. By exercise the mind too is excited to healthy action, its gloomy reveries are dispelled, and the fair face of creation is presented to the mind’s eye in its proper hues. It robs undue mental exertion of half its injurious effects upon the body, whilst it stimulates and directs it in its proper course. It improves the temper, and humanises the character. The disposition is refined, the pa ions restrained, violent emotions checked, the habits improved, and the personal charms promoted under the stimulus of judicious exercise. To females, bodily exercise is even more nece ary than to males. The disposition and education of females are such as tend to produce habits of sloth and indolence to a greater degree than in the other sex. Hence to them exercise is doubly important—it is inseparable from health. The more retiring dispositions of females lead them almost unconsciously into habits of inactivity, which, above all, they should endeavour to shake off and avoid. By so doing—by replacing habits of indolence and inactivity by liveline and moderate exercise, the development of the body will be promoted, additional grace and elegance imparted to its natural movements, and the enjoyments arising from both mental and bodily health increased, whilst disease and deformity will be prevented by the removal of their cause. The nece ity of exercise exists equally in every grade of society and age of life. Those who are engaged in sedentary employments or in-door occupations, should particularly seek refreshing out-door exercise during the periods of relaxation from their diurnal duties. To the studious and delicate of both sexes, this is absolutely nece ary to preserve the health and vigour of the body. In infancy, exercise of a suitable kind should be almost the constant occupation of the little beings that claim our protection and care. It should, however, be always borne in mind, that the muscular exercise of very young children must be of the gentlest cla . Prejudice and ignorance frequently induce nurses and parents to teach their children to walk, as they falsely call it, and thus their feeble limbs are urged to make premature efforts to totter along, before the bones and muscles have acquired sufficient strength to support the body in an erect position. From this course the legs and joints frequently become bent and mi hape ned, and severe injuries are often inflicted on the head and body by blows and falls. It should never be forgotten, that crawling and rolling are their first modes of progre ion, and require the least exertion. Next comes the sitting posture; from this the child gradually advances to the erect one; then to walk by slight a istance; and, lastly, to walk safely alone. All this should come naturally, and never be promoted, further than by laying the infant on the carpet or floor, for the full exercise of its little strength. As soon as a healthy child is able to walk instead of crawl, its own disposition induces it to do so. The faculty of imitation, the spirit of enterprise, and the pride of doing what others do, present even in infancy, is rather apt to lead the infant to over-exertion than the contrary. The practice of constantly ‘dolling’ children in the arms is most prejudicial to the early development of their feeble powers. It is injudicious to take an infant out during the hottest part of the day in summer; such a proceeding tends to enervate and depre , rather than to strengthen him. Whenever he goes out his head should be protected from the direct rays of the sun by means of a large brimmed hat made of cotton or straw and an umbrella. The neglect of these precautions frequently gives rise to the disordered stomach, sickne , and diarrhœa, so prevalent during very hot weather. During other periods of the day, the weather being favorable and the locality healthy, an infant cannot be too much out of doors, especially during teething. Infants of three or four months’ old may, under certain precautions, be sent out into the open air during the winter. They must be well wrapped up; they should be carried in the nurse’s arms, and not consigned to a perambulator; they should never go out in foggy nor wet weather; if the wind be neither in the east nor the north-east there will be no objection to their being sent out on a clear frosty day. Spring is a trying period for infants and children, because of the prevalence of east winds; hence the nece ity of seeing that they are well and warmly clad when sent out during this season. There is much le danger of a child taking cold during the autumn than the spring, as in autumn the winds frequently blow from the south, or warm quarter. In childhood the exercise should be regulated according to constitution and age; avoiding inactivity, on the one hand, and exce ive exercise on the other. The out-door plays and pastimes of BOYS will generally be found sufficient, and in some cases will even require to be curbed, to prevent fatigue and the overtasking of the young frame. With girls it is frequently difficult to find sufficient exercise without trespa ing on the prejudices of the ignorant, or the routine of their daily education. With them walking, and some healthy amusement, as skipping, hooping, or the like, should be indulged in for some hours daily. When this is impo ible or inconvenient, they may be habituated to the practice of the more simply and cleanly portion of the domestic duties. In the performance of the latter, the health will be promoted, whilst the care and attention which is always due by a female to herself and others, at all periods of her life, will become an easy acquisition, and a ist the cultivation of the best feelings of her nature. In youth exercise matures and promotes the development of the frame; and in manhood it is equally nece ary, as already noticed, to keep it in healthy action. In age it will be found to a ist the vital functions, and put off decay. In fact, to all—young, old, rich, and poor, physical exercise is e ential to the permanent enjoyment of health. In a medical point of view, “exercise, employed moderately, has a tonic and stimulating influence on the system, and is calculated to prove beneficial in a great variety of complaints. Used immoderately, it exhausts both the mental and bodily powers, and produces great debility.” (Pereira.) Well-directed exercise favours the preservation of the general health, by calling into direct action the majority of the organs of the body; and it also acts powerfully on the skin, by stimulating its functions, increasing its temperature, awakening its tone, and subjecting it to a current of atmosphere favorable to its respiratory offices. But to be beneficial in the highest degree, exercise must be accompanied by feelings of present interest and enjoyment. The mind must direct and go with it; to ensure its full benefits, the “soul must be present.” “During convalescence, properly regulated exertion is highly serviceable; but it should never be carried so far as to produce exhaustion, and should be pursued for some time in doors, before it be attempted in the open air; the latter, at first, should always take place in a carriage, that can be opened or closed at will; the patient may then attempt short walks in the open air; but, in all cases, it is of importance that he is not unduly fatigued, as, otherwise, injury instead of benefit will be the result. One of the most serious errors, committed with regard to exertion, is that of permitting a convalescent to sit up too frequently, or for too long a time, under the mistaken notion of giving him strength. A patient should never be allowed to sit up longer than is agreeable to his feelings, and never so long as to produce a sense of fatigue.” (Dr R. E. Griffith.) The physiological effects of exercise have been studied by numerous scientific observers. The carefully conducted experiments of Dr Edward Smith have satisfactorily demonstrated that during bodily exertion the circulation of the blood through the lungs is much increased in velocity, that these latter inspire air and eliminate carbonic anhydride in quantities proportionate to the exercise taken, and that these quantities show an enormous increase over the amounts of these gases inhaled and exhaled during a state of rest. Adopting the recumbent position as unity, Dr Edward Smith has given the following table, illustrating the quantities of air inhaled during various forms of exercise: | Lying position | 1· | | Sitting | 1·18 | | Standing | 1·33 | | Singing | 1·26 | | Walking 1 mile per hour | 1·90 | | Walking 2 miles per hour | 2·76 | | Walking 3 miles per hour | 3·22 | | Walking and carrying 34 lbs. | 3·50 | | Walking and carrying 62 lbs. | 3·84 | | Walking and carrying 118 lbs. | 4·75 | | Walking at 4 miles per hour | 5· | | Walking at 6 miles per hour | 7· | | Riding and trotting | 4·05 | | Swimming | 4·33 | | Treadmill | 5·50 | Since a man takes into his lungs 480 cubic inches of air per minute, in walking four miles an hour he draws in 2400 cubic inches, and if six miles 3260 cubic inches a minute. [289] [289] Parkes. Dr Smith estimated the amount of carbonic anhydride evolved under differing conditions, and found that— | Carbonic acid exhaled per minute in grains. | | During sleep | 4·99 | | Lying down, and almost asleep (average of three observations) | 5·91 | | Walking at the rate of 2 miles an hour | 18·10 | | Walking at the rate of 3 miles an hour | 25·83 | | Working at the treadmill, ascending at the rate of 26·65 feet per minute (average of three observations) | 44·97 | The relative amounts of carbonic anhydride eliminated from the lungs during periods of rest and exercise have also been investigated by Pettenkofer and Voit. The following table, which gives the results of their experiments, also records the quantities of oxygen absorbed, and of water and urea excreted at the same time:— | Absorption of Oxygen in Grammes. | Elimination in Grammes of— | | Carbonic Acid. | Water. | Urea. | | Rest-day. | 708·9 | 911·5 | 828·0 | 37·2 | | Work-day. | 954·5 | 1284·2 | 2042·1 | 37·0 | | Exce on work-day (with exception of urea) | 246·6 | 372·7 | 1214·1 | 0·2 | 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 exce ive. [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 e ential 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 e ential 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 nece arily becomes le diluted and richer in quantity. [291] “Deficient exercise is one of the causes which produce those nutritional alterations in the lung which we cla 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 exce ive, 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] [292] Parkes. Palpitation, enlargement, and valvular disease of the heart result from exce ive or injudicious exercise. Wherever, therefore, fatigue or embarra ment 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 doubtle 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 exce ive exertion, without sufficient rest, has been found to interfere with their nutrition, and to cause them to become soft. There is a tolerably general impre ion 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 Profe or Wilson, of Edinburgh. On this point Dr Parkes says: “Considering that perfect nutrition is not po ible except with bodily activity, we should infer that sufficient exercise would be nece ary 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 le 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 pota ium phosphate; the venous blood pa ing from the muscles becomes much darker in colour, is much le rich in oxygen, and contains much more carbonic acid (Sczelkow); the extractive matters soluble in water le en, 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 le , 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 carn is 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, .; 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 nece ity 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 nece ary. 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 proce 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 ti ue. 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 proce 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 a ume 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 nece ary, 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. Profe or Haught on, 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:— | Labouring Force of Man. | | Kind of Work. | Amount of Work. | Authority. | | Pile-driving | 312 | tons lifted 1 foot. | Coulomb. | | Pile-driving | 352 | ” | Lamaude. | | Turning a winch | 374 | ” | Coulomb. | | Porters carrying goods, and returning unladen | 325 | ” | ” | | Pedlars always loaded | 303 | ” | ” | | Porters carrying wood up a stair, and returning unloaded | 381 | ” | ” | | Paviours at work | 352 | ” | Haught on. | | Military prisoners at shot drill (3 hours), and oakum-picking and drill | 310 | ” | ” | | Shot drill alone (3 hours) | 160·7 | ” | ” | Profe or Haught on 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:— | Kind of Exercise. | Work done in 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 busine of life, this amount may be in many cases reduced;” and concludes by saying, “It is not po ible to lay down rules to meet all cases, but probably every man with the above facts before him could fix the amount nece ary 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 le seriously affected by an exce ive indulgence in it, which shows itself in spitting of blood and in congestion of the pulmonary ve els. 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 nece ity 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. [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 nece ary. 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 le en 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 pota ium 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 North umber land, the 300,000 miners in England break down prematurely from bronchitis and pneumonia, caused by the atmosphere in which they are compelled to work.