CHAPTER V.

STIFFNESS.

Return to the Gymnasium; A Sleepless Night-Febrile Stiffness -Three Degrees of Stiffness of Fatigue-Causes of Stiffness; Immunity due to Habituation-Explanation of Symptoms Imperfection of Theories - Local Symptoms; They are due to Trauma - General Symptoms; They are due to AutoIntoxication Deposit of Urates - Influence of Muscular Exercise on their Formation; Diversity of opinion of Authors -Personal Observations-Conditions which cause Variations in the Formation of Deposits after Work-Slow appearance of the Deposits after Exercise-Influence of the Intensity of the Work on their Formation - Hitherto misunderstood influence of Training Constant Correlation observed between the Production of Stiffness and the Formation of Deposits--This Correlation is found in all circumstances which render the Individual more liable to Fatigue-Influence of Moral Causes on Consecutive Fatigue and on the Deposits.

IF a person has for some months taken no active exercise, and then returns to the gymnasium, he usually finds at the outset that he retains all his old vigour. He performs all the most difficult movements with as much ease as when they were assiduously practised. He gives himself up to the pleasure of long-discontinued performances, he is prodigal with the work of his muscles, and finally, after a long practice, he goes away astonished at feeling no fatigue after an hour so well spent.

In the evening, however, a little weariness and sleepiness make him think that the violent exercise he has taken makes him need more sleep than usual, and he hastens to seek in sleep the reparation of the force he has expended.

But sleep does not come. It is made impossible by

excessive agitation, by insupportable heat throughout the body, by pains in the head, even by delirium. If towards daybreak he goes to sleep for a short time, he awakes shaken, bathed in sweat; his limbs are so stiff that he cannot move them; his head is heavy, his tongue coated, his appetite lost.

During the day the fever declines; but there remains. a general condition of discomfort, of inability to work, a sensation of extreme lassitude.

Usually after twenty-four hours the general disturbances have disappeared, but there remain local sufferings, and for five or six days to come all the muscles which have taken part in this forced exercise remain stiff, painful and powerless.

This is the ordinary picture of the Stiffness of fatigue.

I.

Stiffness does not always present the same train of symptoms, for there are several degrees of it.

If the exercise we have not practised for some time be executed with a certain moderation, and especially if it be confined to localised muscular groups, its effect usually remains local, and is limited to muscular pains which for some days hinder the movement of the limbs employed in the exercise. This is stiffness of the first degree.

If the muscular efforts have been intense and prolonged, without too much exceeding the power of resistance of the system, general disturbances are added to the local pains, and produce an indefinable sensation of lassitude, of unfitness for work, which extends even to muscles which have taken no part in the exercise. But the pulse remains quiet, nor is there any characteristic symptom of fever. Slight depression, increased sensibility to cold, are the only witnesses to a passing disturbance of health.-This is the stiffness of the second degree; it is that which is most commonly observed, and that which we shall more particularly study.

Finally, when the exercise has been excessively

violent, or when it has been performed by one whose system possesses little power of resistance, the ensuing disturbance takes the form of an attack of fever. This is febrile stiffness, such as we described at first.

The fever of stiffness, a typical form of consecutive fatigue, does not usually begin till some hours after the exercise which has caused it.

It may be ushered in by a rigor, and have the whole appearance of a severe febrile affection. The severity. of the symptoms may sometimes lead the physician to a false diagnosis, and make him suspect the onset of an eruptive fever, a malarial fever, or some other affection which begins with severe fever. Moreover in some cases it may last longer than usual-for three, four, or more days.

The intensity of the stiffness is not always in proportion to the immediate fatigue, to that which is felt during the exercise, and which forces the muscles to rest. Exercise is sometimes followed by stiffness without having been accompanied by any muscular fatigue during its performance. Sometimes, on the other hand, an exercise is pushed to the utmost limits of a man's powers, without the slightest disturbance following.

This is because stiffness depends rather upon the conditions of the worker, than on those in which he performs the work. A moderate exercise, such as walking, may result in febrile stiffness in a man accustomed to complete inactivity, while running or fencing will produce in a well-trained man not even a local consecutive disturbance.

Before examining the reasons for this immunity produced by habit, it is necessary to establish the cause and the mechanism of stiffness.

And first we must divide in two classes the phenomena observed in persons suffering from stiffness. We must study separately the local symptoms and the general symptoms of this form of fatigue.

The local symptoms have been more studied than the others, but, according to Richet,* they have not yet been

Richet. Les Muscles et les Nerfs.

satisfactorily explained. Under the influence of the organic combustions which accompany muscular work, an excess of lactic acid is produced in muscle. According to the recognised theory, this substance, impregnating and saturating the muscular fibre, causes it for the time to lose its contractile power.

"But firstly," says Richet, " recent experiments have shown that little lactic acid is produced during contraction. Secondly, the alkaline blood passing constantly through the muscle would instantaneously neutralise the lactic acid formed. Finally, how do you explain that several days after the fatigue, this cr that muscle remains painful? Assuredly there no longer remains a trace of the lactic acid produced by the contractions of seventy-six hours before."*

We believe that the persistent local pains of stiffness are to be explained by a series of small material lesions.

If we submit any region of the body to violent compressions, to prolonged manipulations like those which would result from an excessively violent massage, we produce in the muscular masses thus treated, persistent painful phenomena, perfectly analogous to the muscular pains of stiffness.

On the other hand we often see excessive work produce in muscles, tendons, and synovial membranes, a series of lesions exactly similar to those which would be produced by external violence. Inflammation of muscles running

Lactic acid, however, plays an important part in the local phenomena of stiffness. But its action is transient. To the presence of lactic acid we must attribute the stiffness which is almost instantaneously produced in an overworked limb when the circulation in it begins to slacken during repose. This stiffness, which makes it so painful to resume work, is dissipated by a few energetic efforts, which re-establish the circulation in the muscles. The stiffness which comes on with repose is not so much due to the cooling of the muscle as to the slowing of the circulation. When the muscle ceases to contract, the blood does not so freely bathe the muscle fibre. When work is resumed, the blood-current, more active again, carries away the lactic acid with which the fibre is impregnated, and further, thanks to its alkalinity, it neutralises this acid.

on to suppuration, inflammation of synovial sheaths with painful crepitation of tendons, may result from overwork of motor organs, just as from external violence. This is because the mechanism of the accidents is in both cases the same.

The muscular pain felt in a muscle which has done too much work is only the first degree of a series of small lesions similar to those which are observed after any injury. We need be no more astonished at the prolonged painfulness of the muscular fibre bruised by unusual work, than by the persistence of blisters on the skin irritated by a body which the hand is not used to hold. A series of small lesions of the motor organs may result from violent exercise. We can make no better comparison than to the different injuries which may be produced in a machine by excessive work. Just as in the machine, the bands may become loose, the bearings roughened and the oil dried up.

But the general phenomena of consecutive fatigue cannot be explained mechanically. They are of an essentially vital order, and have no analogies in any machine constructed by the hand of man.

Febrile stiffness has the general appearance of a mild infectious disease. It resembles most nearly intermittent fever, if we suppose the latter to be limited to one attack. Mild septic intoxications have also a very marked resemblance to the fever of fatigue. It is the same with the onset of the eruptive fevers, and with all febrile states characterised by the presence within the economy of an injurious substance, against which the vital organs

re-act.

Does not the resemblance of the symptoms point to a similar cause, and can we not refer stiffness to an infectious process or a poisonous material? We know that the combustions of muscular work produce changes in the living tissues which profoundly alter their structure, and we know further that the products resulting from these phenomena of combustion, or dissimilation are dangerous to life, and must be speedily eliminated.