Thus every moment, in gymnastic exercises, the vertebral column actively associates with the action of the limbs to finish a movement which they have begun. Most exercises performed with the aid of apparatus seem to make only the arms work, but they really need the very active concourse of the muscles which move the spine. Often in breasting movements the muscular action is facilitated by an imperceptible movement of flexion of the vertebral column which curves the back, or by an effort of extension which hollows it.

In the cases we have quoted, the vertebral column has an active part, through the muscles attached to it, which energetically participate in the work. There are other circumstances in which the bony column has a passive share, and simply is influenced by the weight. In a man hanging by the arms from a trapeze, whose body is vertical from its own weight, all the muscles of the back are completely relaxed, but the vertebræ to which they are attached undergo the traction of the weight of the body, suspended in space. The point of suspension, which is at the level of the shoulders, corresponds to the first dorsal or last cervical vertebra. From this point of attachment the whole body is subject to the weight which draws it down, and it is easy to understand how the dorsal curvature of the spine becomes diminished, for all the movable pieces of which it is made up tend to take the direction of a plumb-line.

The same result is brought about if the body, instead of being suspended by the arms, is supported by them. Instead of holding his arms above his head and seizing a bar, the gymnast can, with his legs downward, rest on the parallel bars supported by his arms. In this case the point of support will be at the same level as was just before the point of suspension, and the body will be just as passively abandoned to the weight which tends to efface the curves of the spine.

Numerous gymnastic movements need that the body should remain for a moment in this inert condition, supported, or suspended by the arms. But these are usually merely preliminary positions, and the spinal

column is soon associated in various evolutions which no longer allow it to play a merely passive part.

On the trapeze, the rings, the horizontal bar, the period of suspension of the body by the arms is merely a sort of short preface to the exercise. Climbing a ladder or a rope by the hands alone, allow, on the contrary, a man to leave throughout the whole exercise his trunk inert and supple, while the arms alone are at work.

On the parallel bars the body is supported by the arms, and remains inert during the movements of horizontal progression brought about by the regular movements of the hands. A great number of the movements performed on the parallel bars allow the spinal column to benefit by the action of the weight which tends to lessen its curves.

From an orthopedic standpoint, the mechanism of the exercises of which we have just been speaking, has been made use of in the correction of deviations of figure. Most of the cures of the "Swedish" gymnastics are based upon the method of suspending the patient by the hands or supporting him by the arms, the body being abandoned to the weight which tends to straighten the crooked spine.

The compass of this volume will not allow us to study in detail the different exercises, and to analyse and explain their mechanism, that is the manner in which they bring into play the different bony levers of which the animal machine is made up. We have merely been able broadly to delineate the mode of action of each part of the body in muscular work, and to indicate the part played by the limbs, the pelvis, the vertebral column, and the ribs in the more common movements.

This rapid sketch has for its special object to make the changes comprehensible which each exercise can produce in the different regions of the body, whether by chiefly developing certain muscular groups which act more than the others, or by modifying the direction of certain bones or bony systems, which support directly or indirectly pressures and shocks, or are placed in vicious attitudes.

PART V.

THE RESULTS OF EXERCISE.

DEVELOP

GENERAL EFFECTS OF EXERCISE-EXERCISES WHICH THE CHEST-LOCAL EFFECTS OF EXERCISE-EXERCISES WHICH PRODUCE DEFORMITY-EXERCISES WHICH DO NOT PRODUCE

DEFORMITY.

CHAPTER I.

GENERAL EFFECTS OF EXERCISE.

66

Varying Nature of the Effects of Exercise-Its two Chief Results, the Losses and the Gains-Increased Activity of Combustions, Resulting in the Using-up of the Reserve Materials-Why is Nutrition more Active?-Part Played by Oxygen-The "Need for Exercise"; to What it is Due-Accumulation of Reserve Materials-Sluggish Nutrition-Why an Inactive Man Fears Fatigue " - Insufficient Exercise Unwholesome Effects on Nutrition-Slackening of the Process of Dissimilation-Obesity -Deficient Oxygen and Excess of Reserve Materials-Incomplete Oxidations-Gout-Necessity for Exercise-Effects Common to all Forms of Muscular Work-Special Effects according to the Quality of the Work-Observation on Horses -Trotting and Walking.

I.

If we go into a gymnasium and examine a group of men who are doing exercise by the doctor's orders, we can hardly believe that the same medicament can be suitable for such different temperaments, for such widely opposed disturbances of health. We ask how the same method of treatment can be advantageously applied to men of a stout build, with red faces and exuberant flesh, and to men who are thin, pale, and emaciated.

It will surprise us, however, after a few weeks, when we come to study afresh these different types, to find how much less contrast they now exhibit in structure and physiognomy. The heavy man has lost weight, while the man who was too light has gained it; the former has no longer the violet tint which announced vascular plethora; the latter, on the contrary, has a brighter colouring: the blood flows to his formerly discoloured cheeks, and his whole appearance announces a more intense life.