Science.

Alexandra Herald and Central Otago Gazette, Issue 422, 26 May 1904, Page 7

Science.

BODILY BXEBCISB, ; *pf;HE number of bodily ailments M'Xg. which result from inactivity is far beyond what is popularly thought'.Fe>p)e who lead indolent Uvea are not in that perfect condition of health which is the common heritage of all who pay dne regard to Nature's laws. We are animals, after all is said and done j< and we have mnsoles of movement like the rest of our kind. Theae muscles are evidently intended for daily me j whether. at work an a labouring man or in the more, refined exercises of the sporting gentleman. Exercise is but so much muscular work; performed with a view to promote herit \ strength, or skill. The labourer who carries bricks up a building and the athlete who rows in a boat are both doiagmtucolar work. The only difference between the labourer and the gentleman in,,thJs respect is that the one can command his time, he can feed well, and tase ateep as he pl«atef| while toe other feeds but badly, works too mftoh, and in. all probability does not sleep as Nature require*. On this account work wears" out' fche otte, while exercise strengthens, the other. Excemive athletic exercises -and excesdve manual labour tend both of them to the same end, vis., exhaustion and overwork.

■ The immediate agents iB movement of any.kind are the amsclea j and in order to realise the benefits of bodily exercise we should ascertain in what way nse of the muecles can promote health. Most of us can remember having bent the forearm upwards to. see a strong muscle of the upper arm swell up. This muscle ia ' the biceps,' and. from the extent of its enlargement we used., to judge of the power of the arm. All muscle structures are elastic; they contract and relax. Whenever a muscle is contracted its body becomes thicker and larger, while its ends remain fixed to the bones. That hap* pehed when our' bicepß' swelled up, happens always,, and to all muscles when tqey contract. Now, running alongside and between some of the muscles of our limbs there are large and important vein's!. These • Bins are carrying the venpuß blood back-to the heart. t The ' nutriment which the food contained when 'itleft'the heart as arterial blood has been used up, so that it is now going back tobe re-purified, and to bring with it more Nourishment. "When, therefore; the . muscles contract exercise, they compress these veins, and bo squeax.9 the t blood onwards, causing it to pass along faster than it - would have done if the muscles had remained at xeßt. Taking these two statements as representing the facts, we inquire what are the benefits which result to the owner of the muscles. In the first place, remember that the heart baa to pump the blood with such force as will drive it, not only through the arteries to the lowest part of the body, but also up again by the veins. When.. therefore, the .muscles contracts aad squeeze the veins,ithey are really assisting the heart in its work- The heart's beat* ing goes on at the same rate, but the force of the beat is assisted by a kind of aspiration, which draws the blood onwards, instead of leaving it to be pushed along by the heart alone. By way of illustration, while we write there are some men in the street laying down telephone cables. They have two openings m the pavement, a distance apart; at one of them the men are pushing the cable along a tube, and at she other opening two men are pulling the same cable through. Tbe pushing men represent the heart forcing the blood on, the pulling men represent the drawing action caused by the squeezing of the contracting muscles. The time occupied by a single contraction is, of course, very short; but .i? tbe exercise is continued, these brief spaces total up to. something of considerable importance. If this point has been made clear, then the next great benefit followa-quite naturally. When a muscle is active more blood is drawn towards it than would reach it in a state of repose. The blood flow being acoelerated by compression os tbe muscles, more nourishment must reach them than would do so if the stream flowed more slowly. Active muscles become, as it were, more thirsty tor the blood, and the compression we have referred to increases the speed of the flow. - This thirst is not for the mere flnid itself, but for the additional nutriment which as increased blood flow would bring. Hence it is a vital law that the nutriment of a muscle is in proportion to the quantity of blood that passes through it. Consequently the more the muaoles are exercised within reasonable bounds, the.more nutriment they receive and the healthier and more powerful they become. Exercise exerts a considerable influence on the nutrition of the muscles; and-to this influence is due the change which we notice in the appearance of the limbs when the muscles are habitually active. To bring thlß faot home, fancy that we are looking at a city clerk, who rides to and from his office, and sits upon a stool all day long. What will his physique be like, if we place Sandow by his side t Now the increased flow of blood, which is called congestion, and which involves an increase also .of the nourishment to the muscles, is .shared by all the orgasi of the body It is not merely the muscles of the arms and legs which benefit; thexe is a.congestion in every part of the system. The consequence of this general congestion, is that there is a more active performance of every function of ..the body. This active congestion is the useful purpose of all bodily exercises, and to it they owe their strengthening power. After a good, sharp walk, we realise that the brain ia clearer, and the spirits are much brighter j although the exercise of walking iB performed almost automatically. The braia has merely occupied itself in considering shop windows, or in admiration of the country lanes through which it passed. How is it, then, that the brain derived benefit from movement of the arms and legs ? It must be the result of the increas9d supply of nutriment which has been brought to it by an increased blood supply. Indigestion might afford uf another example of general systematic benefit. More blood is conveyed to the digestive apparatus during exercise, and so the glands secrete more of the digestive fluids; and, in tbe result, there are more complete' chemical changes in the food, and nn absence of the former discomfort and pain. -It is hardly necessary to multiply ..instances, for, when once the principle has been grasped, its application aU round is quite a simple matter. We can now consider another change which takes place in the muscles dating bodily exercise. The increased natri« ment means increase in the tissue

changes, called combustion. If a muscle, like our fire-stove, takes on more fuel, there must of necessity be a proportionate increase of the waste ■ produced, The muscles consume what they can of the extra fuel, and then give off an equivalent waste. There, is .a continuous exchange going on; the varied structures of the body take up and ntitiee the increase of nutriment, and throw off a proportionate increase of waste material.