The object in administering a dose of assistive movement is to enable the patient to accomplish more than he could do unassisted. Thus it may serve its purpose in either of two ways: first, by enabling the patient to perform a movement without undue fatigue or strain; second, by enabling him to do so through a greater amplitude than he could otherwise manage.

But a nicety of judgment and an exquisite tact are required to enable the masseur to decide how much assistance is to be given, be it manual or mechanical, or by the use of gravity alone. It also requires common sense. For instance, let us take the case of a patient with a wasted deltoid who is told to raise his arm into a position of full abduction at the shoulder by means of a weight and pulley. It is not unusual to find that the masseur allows the patient to perform almost the entire movement with the scapula; or, perhaps, fondly imagines that by increasing the weights the exercise to the deltoid will be increased, whereas the real effect is to render elevation of the arm more easy, while only increasing the exercise of the adductors.

If, on the other hand, the deltoid is called upon to abduct the arm in the standing position before it has adequate strength to accomplish the movement, it will frequently be found that the muscle makes no attempt to perform its hopeless task. It remains quite inert, and any movement that is accomplished is the result of scapular movement. Place the same patient fully recumbent, supporting the weight of the limb on the couch, and the deltoid will at once respond to the call for abduction by a contraction, provided that there is any continuity of nerve supply and that the patient, from desuetude, has not forgotten how to pass his voluntary impulse along the nerve to the muscle.

Another point, frequently overlooked, but worthy of the closest attention, is this: There is a universal law that if one muscle contracts, and movement of a joint takes place in consequence, some other muscle or group of muscles must relax. This does not mean to imply that, during contraction of a muscle, its antagonist passes into a condition of complete flaccidity. This is not so. The elongation of the antagonist is due to an active and voluntary relaxation, and the amount of the relaxation performed at any given moment is dependent on the voluntary control of the movement at the joint. Thus, if a muscle is made to contract and the joint it controls is free to move, and if movement is voluntarily prohibited, the antagonist contracts with exactly the same strength as the muscle concerned. If movement takes place as the result of muscle contraction, the antagonist voluntarily "pays out the slack," as it were, to allow the amount of movement that is required. And this it can do albeit that it is in a state of constant contraction even while visibly relaxing. The relaxation, in other words, can, in accordance with voluntary control, be negative, partial or complete. If movement is prohibited, as by a splint, and a muscle is called upon to contract, the antagonist may pass into a condition of complete relaxation, equivalent to that which would be allowed were full freedom of action given to the muscle contracting. If any severe effort is made, probably the whole of the muscles throughout the limb will pass into a state of contraction, including the antagonist. Let us be sure also that, when we want to assist the movement performed by one muscle, we are not merely giving a resistive movement to its antagonist.

A third consideration is of vital importance to the success of the administration of assistive movement, namely, that the dose of assistance is progressively lessened if the range of movement is unaltered. On the other hand, with increase of range of movement there should be no increase of assistance, unless the resistance to be overcome is out of proportion to the increased range.

Let us now consider in detail the various methods in which assistive movement can be administered.

The most simple has already been mentioned, namely, assistance rendered to the movement of a limb which is floating freely in a water bath. If the patient is sufficiently bad to require this treatment, it will probably be necessary to make our first movements purely passive, and then to instruct the patient to make an effort to copy, while we merely guide the movement.

The next stage is to teach the patient to perform slight movements with the assistance of gravity, then pure free movements and, finally, movements against the resistance of gravity.

When voluntary movement has been restored to this extent, assistance should not be given to such portion of the movement as can be performed voluntarily; but, as the power to complete the movement gradually fails, we commence, and equally gradually increase, the assistance given. But as our assistance is only a means to an end, it is essential that we should note the amount of assistance given on any one day, and aim to secure a similar result with a decreased amount of assistance at some definite date in the near future. The amount of improvement may indeed be infinitesimal, but still it should be there and should be noted, otherwise we are wasting time.

There is one exception to the rule always to allow a patient to perform a movement without aid as far as possible, and then gradually to add and increase assistance. No movement should ever be allowed, the performance of which calls forth coarse, functional tremor in the contracting muscles. The contraction must be stopped immediately and the patient shown how to perform the movement without tremor - by first performing it for him with all the muscles in a state of active relaxation and then allowing the muscles gradually to assist. In other words, the patient assists the masseur rather than vice versa. If any difficulty is encountered by the patient in the performance of the contraction of any muscle, he must be shown how the corresponding muscle on the sound side contracts and then learn to copy it on the injured side.