If we sum up the facts we have just enunciated, we shall be driven to the conclusion that, in order to raise the ribs and get rid of the vicious conformation of flat chest, we must not seek to act directly on the thoracic muscles, but to produce as extensive respiratory movements as possible.

There are two methods of amplifying respiration; one consists in voluntarily expanding the thorax in all directions. This method is in the domain of "chamber-gymnastics"; it has been much extolled, and it may give good results. The other method comes more directly into the field of our studies. It consists in increasing by exercise the amplitude of the respiratory movements.

II.

The problem has now become clear and definite. We need, in order to develop the chest, to know what exercises are most fitted to produce a series of very extensive respiratory movements. Now the amplitude of respiration, as well as its frequency, is in direct ratio to the intensity of the respiratory need, and we know that the intensity of this need depends on the quantity of mechanical work performed in a given time.*

*

The exercises which cause an accumulation of work are then those most fitted for increasing the size of the thorax, and for demanding increased work from the lungs. And we know that this accumulation of work occurs especially in exercises of strength and speed.

Thus the mechanism of exercise, its performance by the aid of these muscles or of those, are of secondary importance in producing the result of which we are speaking. It matters little by what process the muscular force is expended, provided that there is great expenditure in a short period of time. It is indifferent whether the movements are very slow, each of them representing a great number of kilogrammetres, or whether they are extremely rapid, each movement representing but a moderate effort. It is merely necessary that the sum of work represented "Breathlessness."

☛ See Chapter IV.

by these movements, whether few or many, should be considerable in a short time.

Now the quantity of work which a given muscular group can perform in a given time is subordinated to the strength of this group. There are muscular groups which are too weak to expend much force in a short time. One arm may use its whole strength without its work representing, in the unit of time, a great number of kilogrammetres. So whatever form the exercise takes, if the arm alone is working, we shall not find that the breathing is much quickened. The exercise may induce local fatigue before the intensity of the respiratory need has increased. It may even happen that the work of both arms together does not, after a given time, amount to enough to demand more ample respirations.

It

In general, the exercises which are performed with the legs represent more work than those which are performed with the arms. The muscles of the upper limbs could not support, without extreme fatigue, an expenditure of force which will cause no effort to the lower limbs. is not tiring to anyone to walk 500 metres in five minutes: what gymnast could traverse the same distance in the same time hanging by his hands from a stretched rope? The total mechanical work would be, however, the same; displacing the same weight through the same horizontal distance.

We must not then trust to the muscles of the arms to expand the chest. Muscular exercise can only lead to the development of the thorax in an indirect manner, and in no way by a direct effect comparable to the increase in size of a muscle which works. The muscle which contracts often becomes larger because its nutrition is more active. But the chest only expands when the surcharge of the blood with carbonic acid creates a need of a greater quantity of oxygen for hæmatosis.

It is to the more active respiratory need, to the "thirst for air," that the instinctive movement by which the ribs are more energetically raised is due, in order to draw into the lungs a greater quantity of air.

The thirst for air, carried too far, produces breathless

ness, which is nothing else than a powerless struggle of the system seeking in vain to satisfy a need. When breathlessness is very moderate it causes very ample respiratory movements; but when it is excessive the breathing becomes very shallow as well as very rapid.

So that exercise has no longer any effect in expanding the chest, when breathlessness reaches an extreme degree.

To sum up, the most profitable way of dilating the lungs, developing the thorax and expanding the chest, consists in the performance of exercises capable of increasing the respiratory need, without pushing them so as to produce an extreme degree of breathlessness.

If we pass from physiological explanation to observation of facts, we see that practice gives a striking confirmation of theory.

Exercises of strength lead rapidly to an increase in the size of the thorax. It is the same with exercises of speed when they need very energetic movements. No exercise develops the chest as rapidly as does running, unless it be wrestling.

Mountaineers all have large chests, and the Indians who live on the high plateaux of the Cordillera in the Andes, have been noted for the extraordinary size of their chests. This great development in mountaineers is due to two causes which act in the same direction : frequent ascent of steep inclines, and constant residence at great heights at which the air is rarefied. The climbing of these slopes needs a great quantity of work, which causes increase of the respiratory need; respiration in a rarefied atmosphere obliges a man to take deeper breaths in order to supplement, by the quantity of air breathed, the insufficiency of its vivifying properties.

Singers, with no other exercise but singing, acquire great respiratory power and a remarkable increase in the dimensions of their chests.

Numerous observations prove that it is enough voluntarily to take a certain number of deep breaths every day, to produce, in a short time, an increase in the cir

cumference of the chest which may amount to two or three centimetres.

If we wish to gain the same result from muscular exercise, we must choose a form of work which will increase the intensity of the respiratory effort, that is, an exercise which brings powerful muscular masses into action. We shall thus perform a great quantity of work in a short time without producing fatigue. Now the legs, which possess three times as much muscle as the arms, can perform thrice the quantity of work before being fatigued. The lower limbs are then more capable than the arms of awakening the respiratory need, which is proportional to the expenditure of force.

Thus it is an error to demand from gymnastic exercises practised with appliances, exercises of suspension or support, any development of the chest. The trapeze, the rings, the parallel bars, quicken respiration much less than running. These exercises cause an increase in the size of the muscles, and even of the bones of the regions which work, but they cause very little increase in the dimensions of the thorax.

Men who do much work with their arms have often a conformation which is very imposing at the first glance. They have sometimes broad shoulders; but if the arms have done the work alone, without the assistance of the muscles of the trunk, we easily see that the apparently large size of the thorax is due to an excessive development of the muscles about the shoulder joint, and not to raising of the ribs.

Thus we are on the wrong road when we look for too ingenious means for developing the chest; this result, precious above all, can be obtained without any complicated appliances, without any difficult process, and if we had to formulate concise advice on this subject we should say :

When a young person has a narrow and flat chest, recommend running if it be a boy, or skipping if a girl.

CHAPTER III.

LOCAL EFFECTS OF EXERCISE.

Effects on neighbouring parts. Useful Effects: Compression of Vessels by the Contracting Muscles; Quickening of the Circulation as a result-Disappearance of Edema during ExerciseInjurious Effects of Muscular Contraction: Excessive Compression of Internal Organs-Dangers of Effort Effects of Work on Muscle-Useful Effects: Increase in Size-Injurious Effects; Wasting of the Organ through Excessive Work—The Accidents of Work. Muscular Ruptures-Tendency of Muscular Fibre to Shorten through Excessive Work-Semi-flexion of the Fore-arm in Gymnasts-Dangers of Muscular Contractures— How Deviations of the Spine are produced by Ill-planned Exercise.

MUSCULAR work produces local effects of two kinds. The first kind occurs in the muscles themselves, in the bones which are moved, and in the joints which are the centres of movement. The second occurs throughout the region in which the movement takes place, and concerns organs which take no direct part in the exercise. We shall study separately the direct effects of muscular contraction, and its effects on neighbouring parts.

I.

The chief effects observed in the regions which are the seat of repeated muscular movement are due to the compression which the muscle, in becoming shorter and thicker, exercises on neighbouring parts. This compression may either affect vessels containing fluids, such as the lymph and the blood, or more solid materials, as the intestinal contents, and the pressure may thus be transmitted to remote points. Hence result effects which are not strictly localised, and which serve as a connecting link between the local and the general effects of exercise.