Passive movements form a part, along with active movements, holdings, massage and orthopaedics, of the treatment of certain deformities, particularly of scoliosis or spinal curvature, which is extremely common. Active movements here aim at strengthening the back muscles, passive movements chiefly at stretching shortened ligaments and capsules and at mobilising abnormally immobile parts of the spine. In the special part of this book I accentuate the necessity for less routine among gymnasts, whether medical or non-medical, that they may apply passive movements with the greatest care in order not still further to increase the deformity by too strongly "mobilising."

In regard to the nervous system, there is obviously a great difference between active movement, with its innervation of muscle, and passive movement, without it. Goldscheider and others, however, attribute to passive movements some "assisting" influence. If through paralysis or paresis the power of wrinkling the forehead or bending the elbow is lost, according to this idea one helps to restore this power by giving passive movements purely by opening up a nerve path. To distinguish as regards therapeutic value between active and passive movements in this as in many other matters is very difficult for those who cannot be said to have studied physiology. *****

Gymnastic positions may be more or less active in character. A greater or less amount of static muscle work may go to their maintenance while other persons, apparatus, machines, or weights also work. In regard to muscle work, one may compare, for instance, the fundamental lying position, in which it falls to zero or to a real minimum according to one's idea of the position, with the hanging fundamental position, in which some arm, shoulder and neck muscles are active, and both these with leg-forward-lying position, in which strong and extensive muscle work takes place on the dorsal aspect.

The bones of the skeleton, since they form levers for static muscle work, are affected as to their form by the pull of the muscles in the same way as by movements, and most probably also receive more blood from their nutrient arteries (see below on Active Movements).

With fixation- and joint-apparatus position is also an exercise, especially when taken more accurately as a "holding," not merely as a starting-point for certain movements, and its greatest importance is as a means of stretching contracted joint capsules, ligaments, and other soft parts in cases of faulty position. Swedish medical gymnastics makes use of a great number of positions for the treatment of scoliosis; and among Zander's medico-mechanical apparatus, and other appliances since produced after his model, we find a considerable number which aim at maintaining certain positions with or without movements. We see more distinctly in this department than elsewhere how medical gymnastics touches orthopaedics, as in other directions it borders on massage.

In the muscles working statically, innervated and contracted, to maintain a position the small blood vessels are dilated as in active movements, and carry a richer flow of blood; more food substance is oxidised and more heat produced than during rest. Positions therefore have the same effect as active movements, as I have already pointed out, on the muscles themselves, on the distribution of blood, and, to some extent, on the heart and respiration, the centres for which are stimulated by the products of muscular metabolism. But those effects which in active movements are produced upon the venous circulation by the alternate thinning and thickening of the muscles and by the lengthening and shortening of the blood vessels, as well as by the increase and diminution of Braune's spaces, and in some cases by compression of the liver and spleen, are excluded from static muscle work. Because the blood flow in the vessels and towards the heart is less, and because the products of metabolism which excite the circulatory and respiratory centres reach the circulation less quickly in positions than in movements, the former have less effect than the latter on circulation and respiration. Because the fatigue products are carried away from the muscles less quickly in static than in motor work, the former produces comparatively greater fatigue than the latter. It is manifest that the nerve elements belonging to the motor apparatus are exercised by positions as well as by movements. By careful attention to position some of the effects described above for self-resisted movements may be produced. And although positions are not so much used as movements in Frenkel's compensatory exercise treatment, they are an essential part of this important branch of gymnastics. One cannot doubt that a tabetic patient by standing with eyes shut trying to control Romberg's symptom, in other words to maintain his balance, is exercising what remains of the corresponding sensory neurons in his spinal cord and cerebellum, i.e., his co-ordinating mechanism, or that by standing on one leg with eyes open he is exercising his power of replacing lost sensibility by the sense of sight.